LTC1563-2/LTC1563-3 Active RC, 4th Order Lowpass Filter Family FEATURES DESCRIPTIOU ■ Extremely Easy to Use—A Single Resistor Value The LTC®1563-2/LTC1563-3 are a family of extremely Sets the Cutoff Frequency (256Hz < f < 256kHz) easy-to-use, active RC lowpass filters with rail-to-rail C ■ Extremely Flexible—Different Resistor Values inputs and outputs and low DC offset suitable for systems Allow Arbitrary Transfer Functions with or without with a resolution of up to 16 bits. The LTC1563-2, with a Gain (256Hz < f < 256kHz) single resistor value, gives a unity-gain Butterworth C ■ Supports Cutoff Frequencies Up to 360kHz Using response. The LTC1563-3, with a single resistor value, FilterCADTM gives a unity-gain Bessel response. The proprietary ■ LTC1563-2: Unity-Gain Butterworth Response Uses a architecture of these parts allows for a simple resistor Single Resistor Value, Different Resistor Values calculation: Allow Other Responses with or without Gain R = 10k (256kHz/f ); f = Cutoff Frequency C C ■ LTC1563-3: Unity-Gain Bessel Response Uses a Single Resistor Value, Different Resistor Values where fC is the desired cutoff frequency. For many appli- Allow Other Responses with or without Gain cations, this formula is all that is needed to design a filter. ■ Rail-to-Rail Input and Output Voltages By simply utilizing different valued resistors, gain and ■ Operates from a Single 3V (2.7V Min) to ±5V Supply other responses are achieved. ■ Low Noise: 36µVRMS for fC = 25.6kHz, 60µVRMS for The LTC1563-X features a low power mode, for the lower f = 256kHz C frequency applications, where the supply current is re- ■ fC Accuracy < ±2% (Typ) duced by an order of magnitude and a near zero power ■ DC Offset < 1mV shutdown mode. ■ Cascadable to Form 8th Order Lowpass Filters The LTC1563-Xs are available in the narrow SSOP-16 ■ Available in Narrow SSOP-16 Package package (Same footprint as an SO-8 package). APPLICATIOUS , LTC and LT are registered trademarks of Linear Technology Corporation. FilterCAD is trademark of Linear Technology Corporation. ■ Discrete RC Active Filter Replacement All other trademarks are the property of their respective owners. ■ Antialiasing Filters ■ Smoothing or Reconstruction Filters ■ Linear Phase Filtering for Data Communication ■ Phase Locked Loops TYPICAL APPLICATIOU Frequency Response Single 3.3V, 256Hz to 256kHz Butterworth Lowpass Filter 10 0 3.3V LTC1563-2 0.1µF 12 LSPA LPVB+1165 R VOUT ––1200 fC = R2 5=6 1kH0kz R 345 NINCVA INNVCB111432 R GAIN (dB)––3400 RfC == 1205M6Hz R 6 NC NC11 –50 LPA SB 7 10 –60 R AGND NC VIN 8 V– EN9 R –70 0.1µF –80100 1k 10k 100k 1M fC = 256kHz (1R0k) 1563 TA01 FREQUENCY (Hz) 1563 TA02 156323fa 1

LTC1563-2/LTC1563-3 ABSOLUTE WMAXIWMUWM RATINUGS PACKAGE/ORDER IUNFORWMATIOUN (Note 1) Total Supply Voltage (V+ to V–)............................... 11V TOP VIEW ORDER PART LP 1 16 V+ NUMBER Maximum Input Voltage at SA 2 15 LPB Any Pin....................... (V– – 0.3V) ≤ V ≤ (V+ + 0.3V) LTC1563-2CGN PIN NC 3 14 NC Power Dissipation..............................................500mW LTC1563-3CGN INVA 4 13 INVB Operating Temperature Range LTC1563-2IGN NC 5 12 NC LTC1563C ...............................................0°C to 70°C LPA 6 11 SB LTC1563-3IGN LTC1563I............................................ –40°C to 85°C AGND 7 10 NC GN PART Storage Temperature Range................. –65°C to 150°C V– 8 9 EN MARKING Lead Temperature (Soldering, 10 sec)..................300°C GN PACKAGE 15632 16-LEAD PLASTIC SSOP 15633 TJMAX = 150°C, θJA = 135°C/W NOTE: PINS LABELED NC ARE NOT CONNECTED 15632I INTERNALLY AND SHOULD BE CONNECTED TO THE 15633I SYSTEM GROUND Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for Military grade parts. ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. V = Single 4.75V, EN pin to logic “low,” Gain = 1, R = R11 = R21 = R31 = R12 = R22 = R32, specifications apply to both the high S FIL speed (HS) and low power (LP) modes unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Specifications for Both LTC1563-2 and LTC1563-3 Total Supply Voltage (V ), HS Mode ● 3 11 V S Total Supply Voltage (V ), LP Mode ● 2.7 11 V S Output Voltage Swing High (LPB Pin) V = 3V, f = 25.6kHz, R = 100k, R = 10k to GND ● 2.9 2.95 V S C FIL L HS Mode V = 4.75V, f = 25.6kHz, R = 100k, R = 10k to GND ● 4.55 4.7 V S C FIL L VS = ±5V, fC = 25.6kHz, RFIL = 100k, RL = 10k to GND ● 4.8 4.9 V Output Voltage Swing Low (LPB Pin) V = 3V, f = 25.6kHz, R = 100k, R = 10k to GND ● 0.015 0.05 V S C FIL L HS Mode V = 4.75V, f = 25.6kHz, R = 100k, R = 10k to GND ● 0.02 0.05 V S C FIL L VS = ±5V, fC = 25.6kHz, RFIL = 100k, RL = 10k to GND ● –4.95 –4.9 V Output Swing High (LPB Pin) V = 2.7V, f = 25.6kHz, R = 100k, R = 10k to GND ● 2.6 2.65 V S C FIL L LP Mode V = 4.75V, f = 25.6kHz, R = 100k, R = 10k to GND ● 4.55 4.65 V S C FIL L VS = ±5V, fC = 25.6kHz, RFIL = 100k, RL = 10k to GND ● 4.8 4.9 V Output Swing Low (LPB Pin) V = 2.7V, f = 25.6kHz, R = 100k, R = 10k to GND ● 0.01 0.05 V S C FIL L LP Mode V = 4.75V, f = 25.6kHz, R = 100k, R = 10k to GND ● 0.015 0.05 V S C FIL L VS = ±5V, fC = 25.6kHz, RFIL = 100k, RL = 10k to GND ● –4.95 –4.9 V DC Offset Voltage, HS Mode VS = 3V, fC = 25.6kHz, RFIL = 100k ● ±1.5 ±3 mV (Section A Only) VS = 4.75V, fC = 25.6kHz, RFIL = 100k ● ±1.0 ±3 mV VS = ±5V, fC = 25.6kHz, RFIL = 100k ● ±1.5 ±3 mV DC Offset Voltage, LP Mode VS = 2.7V, fC = 25.6kHz, RFIL = 100k ● ±2 ±6 mV (Section A Only) VS = 4.75V, fC = 25.6kHz, RFIL = 100k ● ±2 ±6 mV VS = ±5V, fC = 25.6kHz, RFIL = 100k ● ±2 ±7 mV DC Offset Voltage, HS Mode VS = 3V, fC = 25.6kHz, RFIL = 100k ● ±1.5 ±3 mV (Input to Output, Sections A, B Cascaded) VS = 4.75V, fC = 25.6kHz, RFIL = 100k ● ±1.0 ±3 mV VS = ±5V, fC = 25.6kHz, RFIL = 100k ● ±1.5 ±3 mV 156323fa 2

LTC1563-2/LTC1563-3 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. V = Single 4.75V, EN pin to logic “low,” Gain = 1, R = R11 = R21 = R31 = R12 = R22 = R32, specifications apply to both the high S FIL speed (HS) and low power (LP) modes unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS DC Offset Voltage, LP Mode VS = 2.7V, fC = 25.6kHz, RFIL = 100k ● ±2 ±7 mV (Input to Output, Sections A, B Cascaded) VS = 4.75V, fC = 25.6kHz, RFIL = 100k ● ±2 ±7 mV VS = ±5V, fC = 25.6kHz, RFIL = 100k ● ±2 ±8 mV DC Offset Voltage Drift, HS Mode VS = 3V, fC = 25.6kHz, RFIL = 100k ● 10 µV/°C (Input to Output, Sections A, B Cascaded) VS = 4.75V, fC = 25.6kHz, RFIL = 100k ● 10 µV/°C VS = ±5V, fC = 25.6kHz, RFIL = 100k ● 10 µV/°C DC Offset Voltage Drift, LP Mode VS = 2.7V, fC = 25.6kHz, RFIL = 100k ● 10 µV/°C (Input to Output, Sections A, B Cascaded) VS = 4.75V, fC = 25.6kHz, RFIL = 100k ● 10 µV/°C VS = ±5V, fC = 25.6kHz, RFIL = 100k ● 10 µV/°C AGND Voltage V = 4.75V, f = 25.6kHz, R = 100k ● 2.35 2.375 2.40 V S C FIL Power Supply Current, HS Mode V = 3V, f = 25.6kHz, R = 100k ● 8.0 14 mA S C FIL V = 4.75V, f = 25.6kHz, R = 100k ● 10.5 17 mA S C FIL VS = ±5V, fC = 25.6kHz, RFIL = 100k ● 15 23 mA Power Supply Current, LP Mode V = 2.7V, f = 25.6kHz, R = 100k ● 1.0 1.8 mA S C FIL V = 4.75V, f = 25.6kHz, R = 100k ● 1.4 2.5 mA S C FIL VS = ±5V, fC = 25.6kHz, RFIL = 100k ● 2.3 3.5 mA Shutdown Mode Supply Current VS = 4.75V, fC = 25.6kHz, RFIL = 100k ● 1 20 µA EN Input V = 3V ● 0.8 V S Logic Low Level V = 4.75V ● 1 V S VS = ±5V ● 1 V EN Input V = 3V ● 2.5 V S Logic High Level V = 4.75V ● 4.3 V S VS = ±5V ● 4.4 V LP V = 3V ● 0.8 V S Logic Low Level V = 4.75V ● 1 V S VS = ±5V ● 1 V LP V = 3V ● 2.5 V S Logic High Level V = 4.75V ● 4.3 V S VS = ±5V ● 4.4 V LTC1563-2 Transfer Function Characteristics Cutoff Frequency Range, f V = 3V ● 0.256 256 kHz C S HS Mode V = 4.75V ● 0.256 256 kHz S (Note 2) VS = ±5V ● 0.256 256 kHz Cutoff Frequency Range, f V = 2.7V ● 0.256 25.6 kHz C S LP Mode V = 4.75V ● 0.256 25.6 kHz S (Note 2) VS = ±5V ● 0.256 25.6 kHz Cutoff Frequency Accuracy, HS Mode VS = 3V, RFIL = 100k ● –2.0 ±1.5 3.5 % fC = 25.6kHz VS = 4.75V, RFIL = 100k ● –2.0 ±1.5 3.5 % VS = ±5V, RFIL = 100k ● –2.0 ±1.5 3.5 % Cutoff Frequency Accuracy, HS Mode VS = 3V, RFIL = 10k ● –5 ±1.5 2.5 % fC = 256kHz VS = 4.75V, RFIL = 10k ● –5 ±1.5 2.5 % VS = ±5V, RFIL = 10k ● –5 ±1.5 2.5 % Cutoff Frequency Accuracy, LP Mode VS = 2.7V, RFIL = 100k ● –3 ±1.5 3 % fC = 25.6kHz VS = 4.75V, RFIL = 100k ● –3 ±1.5 3 % VS = ±5V, RFIL = 100k ● –3 ±1.5 3 % Cutoff Frequency Temperature Coefficient (Note 3) ● ±1 ppm/°C 156323fa 3

LTC1563-2/LTC1563-3 ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. V = Single 4.75V, EN pin to logic “low,” Gain = 1, R = R11 = R21 = R31 = R12 = R22 = R32, specifications apply to both the high S FIL speed (HS) and low power (LP) modes unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Passband Gain, HS Mode, f = 25.6kHz Test Frequency = 2.56kHz (0.1 • f ) ● –0.2 0 0.2 dB C C V = 4.75V, R = 100k Test Frequency = 12.8kHz (0.5 • f ) ● –0.3 0 0.3 dB S FIL C Stopband Gain, HS Mode, f = 25.6kHz Test Frequency = 51.2kHz (2 • f ) ● –24 –21.5 d B C C V = 4.75V, R = 100k Test Frequency = 102.4kHz (4 • f ) ● –48 –46 dB S FIL C Passband Gain, HS Mode, f = 256kHz Test Frequency = 25.6kHz (0.1 • f ) ● –0.2 0 0.2 dB C C V = 4.75V, R = 10k Test Frequency = 128kHz (0.5 • f ) ● –0.5 0 0.5 dB S FIL C Stopband Gain, HS Mode, f = 256kHz Test Frequency = 400kHz (1.56 • f ) ● –15.7 –13.5 dB C C V = 4.75V, R = 10k Test Frequency = 500kHz (1.95 • f ) ● –23.3 –21.5 dB S FIL C Passband Gain, LP Mode, f = 25.6kHz Test Frequency = 2.56kHz (0.1 • f ) ● –0.25 0 0.25 dB C C V = 4.75V, R = 100k Test Frequency = 12.8kHz (0.5 • f ) ● –0.6 –0.02 0.6 dB S FIL C Stopband Gain, LP Mode, f = 25.6kHz Test Frequency = 51.2kHz (2 • f ) ● –24 –22 dB C C V = 4.75V, R = 100k Test Frequency = 102.4kHz (4 • f ) ● –48 –46.5 dB S FIL C LTC1563-3 Transfer Function Characteristics Cutoff Frequency Range, f V = 3V ● 0.256 256 kHz C S HS Mode V = 4.75V ● 0.256 256 kHz S (Note 2) VS = ±5V ● 0.256 256 kHz Cutoff Frequency Range, f V = 2.7V ● 0.256 25.6 kHz C S LP Mode V = 4.75V ● 0.256 25.6 kHz S (Note 2) VS = ±5V ● 0.256 25.6 kHz Cutoff Frequency Accuracy, HS Mode VS = 3V, RFIL = 100k ● –3 ±2 5.5 % fC = 25.6kHz VS = 4.75V, RFIL = 100k ● –3 ±2 5.5 % VS = ±5V, RFIL = 100k ● –3 ±2 5.5 % Cutoff Frequency Accuracy, HS Mode VS = 3V, RFIL = 10k ● –3 ±2 6 % fC = 256kHz VS = 4.75V, RFIL = 10k ● –3 ±2 6 % VS = ±5V, RFIL = 10k ● –3 ±2 6 % Cutoff Frequency Accuracy, LP Mode VS = 2.7V, RFIL = 100k ● –4 ±3 7 % fC = 25.6kHz VS = 4.75V, RFIL = 100k ● –4 ±3 7 % VS = ±5V, RFIL = 100k ● –4 ±3 7 % Cutoff Frequency Temperature Coefficient (Note 3) ● ±1 ppm/°C Passband Gain, HS Mode, f = 25.6kHz Test Frequency = 2.56kHz (0.1 • f ) ● –0.2 –0.03 0.2 dB C C V = 4.75V, R = 100k Test Frequency = 12.8kHz (0.5 • f ) ● –1.0 –0.72 –0.25 dB S FIL C Stopband Gain, HS Mode, f = 25.6kHz Test Frequency = 51.2kHz (2 • f ) ● –13.6 –10 dB C C V = 4.75V, R = 100k Test Frequency = 102.4kHz (4 • f ) ● –34.7 –31 dB S FIL C Passband Gain, HS Mode, f = 256kHz Test Frequency = 25.6kHz (0.1 • f ) ● –0.2 –0.03 0.2 dB C C V = 4.75V, R = 10k Test Frequency = 128kHz (0.5 • f ) ● –1.1 –0.72 –0.5 dB S FIL C Stopband Gain, HS Mode, f = 256kHz Test Frequency = 400kHz (1.56 • f ) ● –8.3 –6 dB C C V = 4.75V, R = 10k Test Frequency = 500kHz (1.95 • f ) ● –13 –10.5 dB S FIL C Passband Gain, LP Mode, f = 25.6kHz Test Frequency = 2.56kHz (0.1 • f ) ● –0.2 –0.03 0.2 dB C C V = 4.75V, R = 100k Test Frequency = 12.8kHz (0.5 • f ) ● –1.0 –0.72 –0.25 dB S FIL C Stopband Gain, LP Mode, f = 25.6kHz Test Frequency = 51.2kHz (2 • f ) ● –13.6 –11 dB C C V = 4.75V, R = 100k Test Frequency = 102.4kHz (4 • f ) ● –34.7 –32 dB S FIL C Note 1: Absolute Maximum Ratings are those value beyond which the life assembly practices are required. There may also be greater DC offset at of a device may be impaired. high temperatures when using such large valued resistors. Note 2: The minimum cutoff frequency of the LTC1563 is arbitrarily listed Note 3: The cutoff frequency temperature drift at low frequencies is as as 256Hz. The limit is arrived at by setting the maximum resistor value listed. At higher cutoff frequencies (approaching 25.6kHz in low power limit at 10MΩ. The LTC1563 can be used with even larger valued resistors. mode and approaching 256kHz in high speed mode) the internal When using very large values of resistance careful layout and thorough amplifier’s bandwidth can effect the cutoff frequency. At these limits the cutoff frequency temperature drift is ±15ppm/°C. 156323fa 4

LTC1563-2/LTC1563-3 TYPICAL PERFORW AU CE CHARACTERISTICS Output Voltage Swing High vs Output Voltage Swing High vs Output Voltage Swing High vs Load Resistance Load Resistance Load Resistance 3.4 5.5 5.5 VS = SINGLE 3.3V VS = SINGLE 5V VS = ±5V 3.2 5.0 5.0 V) 3.0 V) V) E ( E ( 4.5 E ( 4.5 G G G TA 2.8 TA HS MODE TA HS MODE OL HS MODE OL 4.0 OL 4.0 V V V T 2.6 T LP MODE T LP MODE U U U P LP MODE P P T T 3.5 T 3.5 OU 2.4 OU OU 3.0 3.0 2.2 2.0 2.5 2.5 100 1k 10k 100k 100 1k 10k 100k 100 1k 10k 100k LOAD RESISTANCE—LOAD TO GROUND (Ω) LOAD RESISTANCE—LOAD TO GROUND (Ω) LOAD RESISTANCE—LOAD TO GROUND (Ω) 1563 G01 1563 G02 1563 G03 Output Voltage Swing Low vs Output Voltage Swing Low vs Output Voltage Swing Low vs Load Resistance Load Resistance Load Resistance 0.025 0.025 –4.3 VS = SINGLE 3.3V VS = SINGLE 5V HS MODE VS = ±5V –4.4 0.020 HS MODE 0.020 V) V) V) –4.5 TAGE (0.015 LP MODE TAGE (0.015 LP MODE TAGE ( –4.6 L L L O O O V V V UT 0.010 UT 0.010 UT –4.7 P P P HS MODE T T T OU OU OU –4.8 0.005 0.005 –4.9 LP MODE 0 0 –5.0 100 1k 10k 100k 100 1k 10k 100k 100 1k 10k 100k LOAD RESISTANCE—LOAD TO GROUND (Ω) LOAD RESISTANCE—LOAD TO GROUND (Ω) LOAD RESISTANCE—LOAD TO GROUND (Ω) 1563 G04 1563 G05 1563 G06 THD + Noise vs Input Voltage THD + Noise vs Input Voltage THD + Noise vs Input Voltage –40 –40 –40 3.3V SUPPLY 3.3V SUPPLY 3.3V SUPPLY –50 –50 –50 dB) 5V SUPPLY dB) 5V SUPPLY dB) 5V SUPPLY AL (–60 AL (–60 AL (–60 N N N SIG ±5V SUPPLY SIG ±5V SUPPLY SIG ±5V SUPPLY E)/–70 E)/–70 E)/–70 S S S OI OI OI N N N + –80 + –80 + –80 D D D H H H (T fC = 25.6kHz (T fC = 25.6kHz (T fC = 256kHz –90 LOW POWER MODE –90 HIGH SPEED MODE –90 HIGH SPEED MODE fIN = 5kHz fIN = 5kHz fIN = 50kHz –100 –100 –100 0.1 1 10 0.1 1 10 0.1 1 10 INPUT VOLTAGE (VP-P) INPUT VOLTAGE (VP-P) INPUT VOLTAGE (VP-P) 1563 G07 1563 G08 1563 G09 156323fa 5

LTC1563-2/LTC1563-3 TYPICAL PERFORW AU CE CHARACTERISTICS THD + Noise vs Input Frequency THD + Noise vs Input Frequency THD + Noise vs Input Frequency –60 –60 –40 VS = SINGLE 3.3V VS = SINGLE 3.3V VS = SINGLE 3V LOW POWER MODE HIGH SPEED MODE HIGH SPEED MODE –50 dB)–70 fC = 25.6kHz dB)–70 fC = 25.6kHz dB) fC = 256kHz GNAL ( 1VP-P GNAL ( 1VP-P GNAL (–60 SI SI SI E)/–80 E)/–80 E)/–70 1VP-P OIS OIS 2VP-P OIS N N N + + + –80 THD –90 2VP-P THD –90 THD ( ( ( –90 2VP-P –100 –100 –100 1 10 20 1 10 20 1 10 100 200 INPUT FREQUENCY (kHz) INPUT FREQUENCY (kHz) INPUT FREQUENCY (kHz) 1563 G10 1563 G11 1563 G12 THD + Noise vs Input Frequency THD + Noise vs Input Frequency THD + Noise vs Input Frequency –60 –60 –40 VS = SINGLE 5V VS = SINGLE 5V VS = SINGLE 5V LOW POWER MODE HIGH SPEED MODE –50 HIGH SPEED MODE dB)–70 fC = 25.6kHz dB)–70 fC = 25.6kHz dB) fC = 256kHz GNAL ( 1VP-P GNAL ( 1VP-P GNAL (–60 OISE)/SI–80 2VP-P OISE)/SI–80 2VP-P OISE)/SI–70 1VP-P 2VP-P N N N + + + –80 D D D TH–90 TH–90 TH ( 3VP-P ( 3VP-P (–90 3VP-P –100 –100 –100 1 10 20 1 10 20 1 10 100 200 INPUT FREQUENCY (kHz) INPUT FREQUENCY (kHz) INPUT FREQUENCY (kHz) 1563 G13 1563 G14 1563 G15 THD + Noise vs Input Frequency THD + Noise vs Input Frequency THD + Noise vs Input Frequency –60 –60 –40 VS = ±5V VS = ±5V VS = ±5V LOW POWER MODE HIGH SPEED MODE –50 HIGH SPEED MODE dB)–70 fC = 25.6kHz dB)–70 fC = 25.6kHz dB) fC = 256kHz GNAL ( 1VP-P GNAL ( 1VP-P GNAL (–60 SI SI SI OISE)/–80 2VP-P OISE)/–80 2VP-P OISE)/–70 1VP-P 2VP-P N N N + + + –80 THD –90 5VP-P THD –90 5VP-P THD ( ( ( –90 5VP-P –100 –100 –100 1 10 20 1 10 20 1 10 100 200 INPUT FREQUENCY (kHz) INPUT FREQUENCY (kHz) INPUT FREQUENCY (kHz) 1563 G16 1563 G17 1563 G18 156323fa 6

LTC1563-2/LTC1563-3 TYPICAL PERFORW AU CE CHARACTERISTICS Output Voltage Noise vs Cutoff THD + Noise vs Output Load THD + Noise vs Output Load Frequency –70 –70 60 B)–75 L3PV PM-PO SDIEG,N AL VffCINS = == 2 S55kI.NH6GkzHLzE 5V B)–75 2VP-P, 50kHz 2VP-P, 20kHz V)RMS 50 TA = 25°C d d µ AL (–80 LP MODE, AL (–80 SE ( 40 LP MODE NOISE)/SIGN–85 2VP-P SIGNAL NOISE)/SIGN–85 3VP-P, 50kHz 3VP-P, 20kHz GRATED NOI 30 HS MODE (THD + –90 H3VSP M-PO SDIGE,NAL H2VSP M-PO SDIGE,N AL (THD + –90 VHSIG =H S SINPEGELDE M5VODE AL INTE 20 –95 –95 fC = 256kHz OT 10 fIN = 20kHz, 50kHz T –100 –100 0k 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 0.1 1 10 100 1000 OUTPUT LOAD RESISTANCE—LOAD TO GROUND (kΩ) OUTPUT LOAD RESISTANCE—LOAD TO GROUND (kΩ) fC (Hz) 1563 G19 1563 G20 1563 G21 THD + Noise vs Output Load THD + Noise vs Output Load Stopband Gain vs Input Frequency –70 –70 10 LP MODE, fVCS = = 2 ±55.6VkHz 0 fC = 256kHz dB)–75 5VP-P SIGNAL fIN = 5kHz dB)–75 2VP-P, 50kHz –10 AL (–80 LP MODE, AL (–80 –20 E)/SIGN–85 2VP-P SIGNAL E)/SIGN–85 2VP-P, 20kHz 5VP-P, 50kHz N (dB)––3400 LTC1563-2 LTC1563-3 OIS OIS GAI–50 + N–90 HS MODE, + N–90 THD 2VP-P SIGNAL THD VS = ±5V 2VP-P, 20kHz –60 (–95 (–95 HIGH SPEED MODE –70 HS MODE, fC = 256kHz –80 5VP-P SIGNAL fIN = 20kHz, 50kHz –100 –100 –90 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 10k 100k 1M 10M 100M OUTPUT LOAD RESISTANCE—LOAD TO GROUND (kΩ) OUTPUT LOAD RESISTANCE—LOAD TO GROUND (kΩ) FREQUENCY (Hz) 1563 G22 1563 G23 1563 G24 Crosstalk Rejection vs Frequency Crosstalk Rejection vs Frequency –60 –60 DUAL SECOND ORDER DUAL SECOND ORDER BUTTERWORTH BUTTERWORTH –70 fC = 25.6kHz –70 fC = 256kHz HS OR LP MODE HIGH SPEED MODE B) B) K (d–80 K (d–80 AL AL ST ST OS–90 OS–90 R R C C –100 –100 –110 –110 1 10 100 1k 10k 100k 1M FREQUENCY (kHz) FREQUENCY (Hz) 1563 G25 1563 G26 156323fa 7

LTC1563-2/LTC1563-3 PIUN FUUNCTIOUNS LP (Pin 1): Low Power. The LTC1563-X has two operating LPA, LPB (Pins 6, 15): Lowpass Output. These pins are modes: Low Power and High Speed. Most applications will the rail-to-rail outputs of an op amp. Each output is use the High Speed operating mode. Some lower fre- designed to drive a nominal net load of 5kΩ and 20pF. quency, lower gain applications can take advantage of the Refer to the Applications Information section for more Low Power mode. When placed in the Low Power mode, details on output loading effects. the supply current is nearly an order of magnitude lower AGND (Pin 7): Analog Ground. The AGND pin is the than the High Speed mode. Refer to the Applications midpoint of an internal resistive voltage divider developing Information section for more information on the Low a potential halfway between the V+ and V– pins. The Power mode. equivalent series resistance is nominally 10kΩ. This serves The LTC1563-X is in the High Speed mode when the as an internal ground reference. Filter performance will LP input is at a logic high level or is open-circuited. A small reflect the quality of the analog signal ground. An analog pull-up current source at the LP input defaults the ground plane surrounding the package is recommended. LTC1563-X to the High Speed mode if the pin is left open. The analog ground plane should be connected to any The part is in the Low Power mode when the pin is pulled digital ground at a single point. Figures 1 and 2 show the to a logic low level or connected to V–. proper connections for dual and single supply operation. SA, SB (Pins 2, 11): Summing Pins. These pins are a V–, V+ (Pins 8, 16): The V– and V+ pins should be summing point for signals fed forward and backward. bypassed with 0.1µF capacitors to an adequate analog Capacitance on the SA or SB pin will cause excess peaking ground or ground plane. These capacitors should be of the frequency response near the cutoff frequency. The connected as closely as possible to the supply pins. Low three external resistors for each section should be located noise linear supplies are recommended. Switching sup- as close as possible to the summing pin to minimize this plies are not recommended as they will decrease the effect. Refer to the Applications Information section for filter’s dynamic range. Refer to Figures 1 and 2 for the more details. proper connections for dual and single supply operation. NC (Pins 3, 5, 10, 12, 14): These pins are not connected EN (Pin 9): ENABLE. When the EN input goes high or is internally. For best performance, they should be con- open-circuited, the LTC1563-X enters a shutdown state nected to ground. and only junction leakage currents flow. The AGND pin, the LPA output and the LPB output assume high impedance INVA, INVB (Pins 4, 13): Inverting Input. Each of the INV states. If an input signal is applied to a complete filter pins is an inverting input of an op amp. Note that the INV circuit while the LTC1563-X is in shutdown, some signal pins are high impedance, sensitive nodes of the filter and will normally flow to the output through passive compo- very susceptible to coupling of unintended signals. nents around the inactive part. Capacitance on the INV nodes will also affect the fre- quency response of the filter sections. For these reasons, A small internal pull-up current source at the EN input printed circuit connections to the INV pins must be kept as defaults the LTC1563 to the shutdown state if the EN pin short as possible. is left floating. Therefore, the user must connect the EN pin to V– (or a logic low) to enable the part for normal operation. 156323fa 8

LTC1563-2/LTC1563-3 PIUN FUUNCTIOUNS Dual Supply Power and Ground Connections Single Supply Power and Ground Connections LTC1563-X LTC1563-X AGNRAOLUONGD 1 LP V+ 16 V+ AGNRAOLUONGD 1 LP V+ 16 V+ PLANE 2 SA LPB 15 0.1µF PLANE 2 SA LPB 15 0.1µF 3 14 3 14 NC NC NC NC 4 13 4 13 INVA INVB INVA INVB 5 12 5 12 NC NC NC NC 6 11 6 11 LPA SB LPA SB 7 10 7 10 AGND NC + AGND NC V– 8 V– EN 9 0.1µF 8 V– EN 9 0.1µF SINGLE POINT SINGLE POINT SYSTEM GROUND DIGITAL SYSTEM GROUND DIGITAL GROUND PLANE GROUND PLANE (IF ANY) (IF ANY) 1563 PF01 1563 PF02 BLOCK DIAGRAW R21 R22 VOUT R11 R31 R12 R32 VIN 16 V+ C1A C1B SHUTDOWN SWITCH 20k 2 SA 4 – 11 SB 13 – INVA 6 LPA INVB 15 LPB AGND 7 C2A + C2B + 20k AGND AGND AGND SHUTDOWN SWITCH 9 EN 8 V– 1 LP LTC1563-X PATENT PENDING 1563 BD 156323fa 9

LTC1563-2/LTC1563-3 APPLICATIOUNS INUFORWMATIOUN Functional Description resistance in parallel, yields a net effective resistance of 9.52M and an error of –5%. Note that the gain is also The LTC1563-2/LTC1563-3 are a family of easy-to-use, limited to unity at the minimum f . 4th order lowpass filters with rail-to-rail operation. The C LTC1563-2, with a single resistor value, gives a unity-gain At intermediate f , the gain is limited by one of the two C filter approximating a Butterworth response. The reasons discussed above. For best results, design filters LTC1563-3, with a single resistor value, gives a unity-gain with gain using FilterCAD Version 3 (or newer) or contact filter approximating a Bessel (linear phase) response. The the Linear Technology Filter Applications Group for proprietary architecture of these parts allows for a simple assistance. unity-gain resistor calculation: While the simple formula and the tables in the applications R = 10k(256kHz/f ) section deliver good approximations of the transfer func- C tions, a more accurate response is achieved using FilterCAD. where f is the desired cutoff frequency. For many appli- C FilterCAD calculates the resistor values using an accurate cations, this formula is all that is needed to design a filter. and complex algorithm to account for parasitics and op For example, a 50kHz filter requires a 51.2k resistor. In amp limitations. A design using FilterCAD will always yield practice, a 51.1k resistor would be used as this is the the best possible design. By using the FilterCAD design closest E96, 1% value available. tool you can also achieve filters with cutoff frequencies The LTC1563-X is constructed with two 2nd order sec- beyond 256kHz. Cutoff frequencies up to 360kHz are tions. The output of the first section (section A) is simply attainable. fed into the second section (section B). Note that section Contact the Linear Technology Filter Applications Group A and section B are similar, but not identical. The parts are for a copy the FilterCAD software. FilterCAD can also be designed to be simple and easy to use. downloaded from our website at www.linear.com. By simply utilizing different valued resistors, gain, other transfer functions and higher cutoff frequencies are DC Offset, Noise and Gain Considerations achieved. For these applications, the resistor value calcu- The LTC1563-X is DC offset trimmed in a 2-step manner. lation gets more difficult. The tables of formulas provided First, section A is trimmed for minimum DC offset. Next, later in this section make this task much easier. For best section B is trimmed to minimize the total DC offset results, design these filters using FilterCAD Version 3.0 (or (section A plus section B). This method is used to give the newer) or contact the Linear Technology Filter Applica- minimum DC offset in unity gain applications and most tions group for assistance. higher gain applications. Cutoff Frequency (f ) and Gain Limitations For gains greater than unity, the gain should be distributed C such that most of the gain is taken in section A, with The LTC563-X has both a maximum f limit and a mini- C section B at a lower gain (preferably unity). This type of mum f limit. The maximum f limit (256kHz in High Speed C C gain distribution results in the lowest noise and lowest DC mode and 25.6kHz in the Low Power mode) is set by the offset. For high gain, low frequency applications, all of the speed of the LTC1563-X’s op amps. At the maximum f , C gain is taken in section A, with section B set for unity-gain. the gain is also limited to unity. In this configuration, the noise and DC offset is dominated A minimum fC is dictated by the practical limitation of by those of section A. At higher frequencies, the op amps’ reliably obtaining large valued, precision resistors. As the finite bandwidth limits the amount of gain that section A desired fC decreases, the resistor value required increases. can reliably achieve. The gain is more evenly distributed in When fC is 256Hz, the resistors are 10M. Obtaining a this case. The noise and DC offset of section A is now reliable, precise 10M resistance between two points on a multiplied by the gain of section B. The result is slightly printed circuit board is somewhat difficult. For example, a higher noise and offset. 10M resistor with only 200MΩ of stray, layout related 156323fa 10

LTC1563-2/LTC1563-3 APPLICATIOUNS INUFORWMATIOUN Output Loading: Resistive and Capacitive near the cutoff frequency. Poor layout can give 0.5dB to 1dB of excess peaking. The op amps of the LTC1563-X have a rail-to-rail output stage. To obtain maximum performance, the output load- To minimize the effects of parasitic layout capacitance, all ing effects must be considered. Output loading issues can of the resistors for section A should be placed as close as be divided into resistive effects and capacitive effects. possible to the SA pin. Place the R31 resistor first so that it is as close as possible to the SA pin on one end and as Resistive loading affects the maximum output signal swing close as possible to the INVA pin on the other end. Use the and signal distortion. If the output load is excessive, the same strategy for the layout of section B, keeping all of the output swing is reduced and distortion is increased. All of resistors as close as possible to the SB node and first the output voltage swing testing on the LTC1563-X is done placing R32 between the SB and INVB pins. It is also best with R22 = 100k and a 10k load resistor. For best undistorted if the signal routing and resistors are on the same layer as output swing, the output load resistance should be greater the part without any vias in the signal path. than 10k. Figure 1 illustrates a good layout using the LTC1563-X Capacitive loading on the output reduces the stability of with surface mount 0805 size resistors. An even tighter the op amp. If the capacitive loading is sufficiently high, layout is possible with smaller resistors. the stability margin is decreased to the point of oscillation at the output. Capacitive loading should be kept below R11 30pF. Good, tight layout techniques should be maintained VIN LTC1563-X at all times. These parts should not drive long traces and must never drive a long coaxial cable. When probing the 11 23 RR LTC1563-X, always use a 10x probe. Never use a 1x probe. VOUT 22 A standard 10x probe has a capacitance of 10pF to 15pF 32 RR while a 1x probe’s capacitance can be as high as 150pF. The use of a 1x probe will probably cause oscillation. For larger capacitive loads, a series isolation resistor can R12 1653 F01 be used between the part and the capacitive load. If the load is too great, a buffer must be used. Figure 1. PC Board Layout Layout Precautions Single Pole Sections and Odd Order Filters The LTC1563-X is an active RC filter. The response of the The LTC1563 is configured to naturally form even ordered filter is determined by the on-chip capacitors and the filters (2nd, 4th, 6th and 8th). With a little bit of work, external resistors. Any external, stray capacitance in par- single pole sections and odd order filters are easily achieved. allel with an on-chip capacitor, or to an AC ground, can To form a single pole section you simply use the op amp, alter the transfer function. the on-chip C1 capacitor and two external resistors as Capacitance to an AC ground is the most likely problem. shown in Figure 2. This gives an inverting section with the Capacitance on the LPA or LPB pins does not affect the gain set by the R2-R1 ratio and the pole set by the R2-C1 transfer function but does affect the stability of the op time constant. You can use this pole with a 2nd order amps. Capacitance on the INVA and INVB pins will affect section to form a noninverting gain 3rd order filter or as a the transfer function somewhat and will also affect the stand alone inverting gain single pole filter. stability of the op amps. Capacitance on the SA and SB Figure 3 illustrates another way of making odd order pins alters the transfer function of the filter. These pins are filters. The R1 input resistor is split into two parts with an the most sensitive to stray capacitance. Stray capacitance additional capacitor connected to ground in between the on these pins results in peaking of the frequency response resistors. This “TEE” network forms a single real pole. RB1 156323fa 11

LTC1563-2/LTC1563-3 APPLICATIOUNS INUFORWMATIOUN should be much larger than RA1 to minimize the interac- RA1 RB1 R2 R3 tion of this pole with the 2nd order section. This circuit is useful in forming dual 3rd order filters and 5th order filters CP with a single LTC1563 part. By cascading two parts, 7th S INV C1 LP order and 9th order filters are achieved. R1 R2 – VIN VOUT C2 (OPEN) + S INV C1 LP AGND 1/2 LTC1563 – C2 RB1 1563 F03 RA1 ≈ 10 + 1 FP = ( ) RA1 • RB1 AGND 2π • CP RA1 + RB1 1/2 LTC1563 Figure 3 –R2 DC GAIN = LTC1563-2: C1A = 53.9pF, C1B = 39.2pF R1 LTC1563-3: C1A = 35pF, C1B = 26.8pF What To Do with an Unused Section 1 FP = 2π • R2 • C1 1563 F02 If the LTC1563 is used as a 2nd or 3rd order filter, one of Figure 2 the sections is not used. Do not leave this section uncon- nected. If the section is left unconnected, the output is left You can also use the TEE network in both sections of the to float and oscillation may occur. The unused section part to make a 6th order filter. This 6th order filter does not should be connected as shown in Figure 4 with the INV pin conform exactly to the textbook responses. Textbook connected to the LP pin and the S pin left open. responses (Butterworth, Bessel, Chebyshev etc.) all have three complex pole pairs. This filter has two complex pole (OPEN) pairs and two real poles. The textbook response always S INV C1 LP has one section with a low Q value between 0.5 and 0.6. By replacing this low Q section with two real poles (two real poles are the same mathematically as a complex pole pair – C2 with a Q of 0.5) and tweaking the Q of the other two complex pole pair sections you end up with a filter that is + indistinguishable from the textbook filter. The Typical AGND Applications section illustrates a 100kHz, 6th order pseudo- Butterworth filter. FilterCAD is a valuable tool for custom 1/2 LTC1563 filter design and tweaking textbook responses. 1563 F04 Figure 4 156323fa 12

LTC1563-2/LTC1563-3 APPLICATIOUNS INUFORWMATIOUN 4th Order Filter Responses Using the LTC1563-2 10 LTC1563-2 12 LP V+ 1165 R22 VOUT 0 SA LPB 3 14 –20 NC NC R31 4 INVA INVB 13 R32 B) d R21 56 NC NC 1121 GAIN (–40 BUTTERWORTH LPA SB 0.5dB RIPPLE 7 AGND NC 10 –60 CHEBYSHEV R11 8 9 R12 0.1dB RIPPLE V– EN CHEBYSHEV –80 VIN 1563 F05 –90 NORMALIZED TO fC = 1Hz 0.1 1 10 FREQUENCY (Hz) Figure 5. 4th Order Filter Connections (Power Supply, Ground, 1563 F05a EN and LP Connections Not Shown for Clarity). Table 1 Shows Figure 5a. Frequency Response Resistor Values 1 1.2 0 1.0 –2 V) E ( 0.8 G N (dB) –4 VOLTA 0.6 GAI BUTTERWORTH UT BUTTERWORTH –6 0.5dB RIPPLE TP 0.4 0.5dB RIPPLE U CHEBYSHEV O CHEBYSHEV 0.1dB RIPPLE 0.1dB RIPPLE –8 CHEBYSHEV 0.2 CHEBYSHEV NORMALIZED TO fC = 1Hz NORMALIZED TO fC = 1Hz –10 0 0.1 1 2 0 0.5 1.0 1.5 2.0 2.5 3.0 FREQUENCY (Hz) TIME (s) 1563 F05b 1563 F05c Figure 5b. Passband Frequency Response Figure 5c. Step Response Table 1. Resistor Values, Normalized to 256kHz Cutoff Frequency (f ), Figure 5. The Passband C Gain, of the 4th Order LTC1563-2 Lowpass Filter, Is Set to Unity. (Note 1) 0.1dB RIPPLE 0.5dB RIPPLE BUTTERWORTH CHEBYSHEV CHEBYSHEV LP Mode Max f 25.6kHz 15kHz 13kHz C HS Mode Max f 256kHz 135kHz 113kHz C R11 = R21 = 10k(256kHz/f ) 13.7k(256kHz/f ) 20.5k(256kHz/f ) C C C R31 = 10k(256kHz/f ) 10.7k(256kHz/f ) 12.4k(256kHz/f ) C C C R12 = R22 = 10k(256kHz/f ) 10k(256kHz/f ) 12.1k(256kHz/f ) C C C R32 = 10k(256kHz/f ) 6.81k(256kHz/f ) 6.98k(256kHz/f ) C C C Example: In HS mode, 0.1dB ripple Chebyshev, 100kHz cutoff frequency, R11 = R21 = 35k ≅ 34.8k (1%), R31 = 27.39k ≅ 27.4k (1%), R12 = R22 = 256k ≅ 255k (1%), R32 = 17.43k ≅ 17.4k (1%) Note 1: The resistor values listed in this table provide good approximations of the listed transfer functions. For the optimal resistor values, higher gain or other transfer functions, use FilterCAD Version 3.0 (or newer) or contact the Linear Technology Filter Applications group for assistance. 156323fa 13

LTC1563-2/LTC1563-3 APPLICATIOUNS INUFORWMATIOUN 4th Order Filter Responses Using the LTC1563-3 10 LTC1563-3 0 12 LP V+ 1165 R22 VOUT SA LPB –20 3 14 NC NC R31 45 INNCVA INNVBC 1132 R32 GAIN (dB)–40 BESSEL R21 6 11 TRANSITIONAL LPA SB –60 GAUSSIAN TO 12dB 7 10 AGND NC TRANSITIONAL R11 R12 8 V– EN 9 –80 GAUSSIAN TO 6dB NORMALIZED TO fC = 1Hz VIN 1563 F06 –900.1 1 10 FREQUENCY (Hz) Figure 6. 4th Order Filter Connections (Power Supply, Ground, 1563 F06a EN and LP Connections Not Shown for Clarity). Table 2 Shows Figure 6a. Frequency Response Resistor Values 1.2 1.05 BESSEL TRANSITIONAL 1.0 GAUSSIAN TO 12dB OUTPUT VOLTAGE (V) 000...864 BTGREASAUSNSESSLIITAINO NTOAL 12dB OUTPUT VOLTAGE (V) 1.00 TGRAAUNSSSIITAINO NTOAL 6dB TRANSITIONAL 0.2 GAUSSIAN TO 6dB NORMALIZED TO fC = 1Hz NORMALIZED TO fC = 1Hz 0 0.95 0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 TIME (s) TIME (s) 1563 F06b 1563 F06c Figure 6b. Step Response Figure 6c. Step Response—Settling Table 2. Resistor Values, Normalized to 256kHz Cutoff Frequency (f ), Figure 6. The Passband C Gain, of the 4th Order LTC1563-3 Lowpass Filter, Is Set to Unity. (Note 1) TRANSITIONAL TRANSITIONAL BESSEL GAUSSIAN TO 6dB GAUSSIAN TO 12dB LP Mode Max f 25.6kHz 20kHz 21kHz C HS Mode Max f 256kHz 175kHz 185kHz C R11 = R21 = 10k(256kHz/f ) 17.4k(256kHz/f ) 15k(256kHz/f ) C C C R31 = 10k(256kHz/f ) 13.3k(256kHz/f ) 11.8k(256kHz/f ) C C C R12 = R22 = 10k(256kHz/f ) 14.3k(256kHz/f ) 10.5k(256kHz/f ) C C C R32 = 10k(256kHz/f ) 6.04k(256kHz/f ) 6.19k(256kHz/f ) C C C Note 1: The resistor values listed in this table provide good approximations of the listed transfer functions. For the optimal resistor values, higher gain or other transfer functions, use FilterCAD Version 3.0 (or newer) or contact the Linear Technology Filter Applications group for assistance. 156323fa 14

LTC1563-2/LTC1563-3 TYPICAL APPLICATIOUS ±5V, 2.3mA Supply Current, 20kHz, 4th Order, Frequency Response 0.5dB Ripple Chebyshev Lowpass Filter LTC1563-2 10 1 LP V+ 16 V5VOUT 0 2 SA LPB 15 162k 0.1µF –10 3 NC NC 14 –20 169k 4 INVA INVB 13 95.3k B)–30 5 NC NC 12 N (d–40 VIN 274k 274k 6 LPA SB 11 GAI–50 7 10 AGND NC 162k –60 8 9 –5V V– EN ENABLE –70 –80 0.1µF 1563 TA03 –90 1 10 100 FREQUENCY (kHz) 1563 TA04 Single 3.3V, 2mA Supply Current, 20kHz 8th Order Butterworth Lowpass Filter 3.3V 0.1µF 0.1µF LTC1563-2 LTC1563-2 12 LP V+ 1165 82.5k 210k 12 LP V+ 1165 158k VOUT SA LPB SA LPB 3 14 3 14 NC NC NC NC 115k 4 13 196k 75k 4 13 100k INVA INVB INVA INVB 5 12 5 12 NC NC NC NC 137k 6 11 210k 6 11 LPA SB LPA SB 7 10 7 10 AGND NC AGND NC 115k 82.5k 158k 8 9 8 9 V– EN V– EN VIN 0.1µF 0.1µF 1563 TA05 ENABLE Frequency Response 10 0 –10 –20 B)–30 d N (–40 AI G–50 –60 –70 –80 –90 1 10 100 FREQUENCY (kHz) 1563 TA06 156323fa 15

LTC1563-2/LTC1563-3 TYPICAL APPLICATIOUS 100kHz, 6th Order Pseudo-Butterworth Frequency Response 3.3V 0.1µF 10 LTC1563-2 0 12 LP V+ 1165 2R82.72k –10 SA LPB –20 3 14 VOUT 1R73.81k 45 NINCVA INNVCB 1132 2R03.52k N (dB) ––3400 RA1 3.16k RB1 29.4k R21 6 NC NC 11 GAI –50 VIN LPA SB –60 C11 32.4k 7 AGND NC 10 –70 560pF 8 V– EN 9 –80 –90 0.1µF –100 RA2 3.16k RB2 25.5k 10k 100k 1M FREQUENCY (Hz) C12 560pF 1563 TA07a 1563 TA07 The complex, 2nd order section of the textbook design TEXTBOOK BUTTERWORTH PSEUDO-BUTTERWORTH with the lowest Q is replaced with two real first order poles. f 1 = 100kHz Q1 = 1.9319 f 1 = 100kHz Q1 = 1.9319 O O The Q of another section is slightly altered such that the f 2 = 100kHz Q2 = 0.7071 f 2 = 100kHz Q2 = 0.7358 O O final filter’s response is indistinguisable from a textbook f 3 = 100kHz Q3 = 0.5176 f 3 = 100kHz Real Poles O O Butterworth response. f 4 = 100kHz Real Poles O Other Pseudo Filter Response Coefficients (All f Are Normalized for a 1Hz Filter Cutoff) O BESSEL 0.1dB RIPPLE CHEBYSHEV 0.5dB RIPPLE CHEBYSHEV TRANSITIONAL GAUSSIAN TO 12dB TRANSITIONAL GAUSSIAN TO 6dB f 1 1.9070 1.0600 1.0100 2.1000 1.5000 O Q1 1.0230 3.8500 5.3000 2.2000 2.8500 f 2 1.6910 0.8000 0.7200 1.2500 1.0500 O Q2 0.6110 1.0000 1.2000 0.8000 0.9000 f 3 1.6060 0.6000 0.5000 1.2500 0.9000 O f 4 1.6060 1.0000 0.8000 1.2500 0.9000 O The f and Q values listed above can be entered in 4. Enter the f and Q coefficients as listed above. For a O O FilterCAD’s Enhanced Design window as a custom re- Butterworth filter, use the same coefficients as the sponse filter. After entering the coefficients, FilterCAD will example circuit above except set all of the f to 1Hz. O produce a schematic of the circuit. The procedure is as 5. Set the custom F to the desired cutoff frequency. This C follows: will automatically multiply all of the f coefficients. You O 1. After starting FilterCAD, select the Enhanced Design have now finished the design of the filter and you can window. click on the frequency response or step response buttons to verify the filter’s response. 2. Select the Custom Response and set the custom F to C 1Hz. 6. Click on the Implement button to go on to the filter implementation stage. 3. In the Coefficients table, go to the Type column and click on the types listed and set the column with two LP types 7. In the Enhanced Implement window, click on the Active and two LP1 types. This sets up a template of a 6th order RC button to choose the LTC1563-2 part. You are now filter with two 2nd order lowpass sections and two 1st done with the filter’s implementation. Click on the order lowpass sections. schematic button to view the resulting circuit. 156323fa 16

LTC1563-2/LTC1563-3 TYPICAL APPLICATIOUS 22kHz, 5th Order, 0.1dB Ripple Chebyshev Lowpass Filter Driving the LTC1604, 16-Bit ADC 5V 0.1µF LTC1563-2 10µF 12 LSPA LPVB+ 1165 1R3272k 49.9Ω 560pF 12 AAIINN+– LTC1604AAVVDDDD 3356 10Ω + 5V 3 14 R31 4 NINCVA INNVCB 13 R32 2.2µF + 34 VRREEFFCOMP SHDCNS 3332 + 10µF 82.5k 5 12 78.7k 47µF µP RA1 26.7k RB1 215k R21 6 NC NC 11 5 AGND CONVST 31 CONTROL VIN LPA SB 6 AGND RD 30 LINES C11 243k 7 10 560pF AGND NC 7 AGND BUSY 27 8 9 –5V V– EN 8 AGND 11 TO 26 16-BIT 0.1µF 5V + 9 DVDD PARALLEL BUS R12 137k 10 29 10µF DGND OVDD + 5V OR 3V 34 28 VSS OGND 10µF –5V 10µF + 1563 TA08 4096 Point FFT of the Output Data 0 fSAMPLE = 292.6kHz –20 fIN = 20kHz SINAD = 85dB THD = –91.5dB –40 B) d E (–60 D U T LI–80 P M A –100 –120 –140 0 36.58 73.15 109.73 146.30 FREQUENCY (kHz) 1563 TA08a 156323fa 17

LTC1563-2/LTC1563-3 TYPICAL APPLICATIOUS 50kHz Wideband Bandpass 4th Order Bessel Lowpass at 128kHz with Two Highpass Poles at 11.7kHz Yields a Wideband Bandpass Centered at 50kHz 10 5V LTC1563-3 0.1µF 0 1 LP V+ 16 R22 2 15 20k –10 SA LPB 3 14 VOUT R31 4 NINCVA INNVCB 13 R32 N (dB)–20 6C8101pF R11 20k 5 NC NC 12 20k GAI–30 20k R21 6 11 VIN LPA SB –40 20k 7 10 R12 AGND NC 8 9 20k –50 –5V V– EN C12 0.1µF 680pF –60 1k 10k 100k 1M 1563 TA09 FREQUENCY (Hz) 1563 TA09a To design these wideband bandpass filters with the 4. In the Coefficients table, the first two rows are the LP LTC1563, start with a 4th order lowpass filter and add two Type with the f and Q as previously defined. Go to the O highpass poles with the input, AC coupling capacitors. The third and fourth rows and click on the Type column lowpass cutoff frequency and highpass pole frequencies (currently a hyphen is in this space). Change the Type depend on the specific application. Some experimentation of each of these rows to type HP1. This sets up a of lowpass and highpass frequencies is required to achieve template of a 6th order filter with two 2nd order lowpass the desired response. FilterCAD does not directly support sections and two 1st order highpass sections. this configuration. Use the custom design window in 5. Change the frequency of the highpass (HP1) poles to FilterCAD get the desired response and then use FilterCAD get the desired frequency response. to give the schematic for the lowpass portion of the filter. Calculate the two highpass poles using the following 6. You may have to perform this loop several times before formulae: you close in on the correct response. 7. Once you have reached a satisfactory response, note 1 1 f (HPA)= ,f (HPB)= the highpass pole frequencies. The HP1 highpass poles O O 2•π•R11•C11 2•π•R12•C12 must now be removed from the Custom design coeffi- The design process is as follows: cients table. After removing the highpass poles, click on the Implement button to go on to the filter implementa- 1. After starting FilterCAD, select the Enhanced Design tion stage. window. 8. In the Enhanced Implement window, click on the Active 2. Choose a 4th order Bessel or Butterworth lowpass filter RC button and choose the LTC1563-2 part. Click on the response and set the cutoff frequency to the high schematic button to view the resulting circuit. frequency corner of the desired bandpass. 9. You now have the schematic for the 4th order lowpass 3. Click on the custom response button. This copies the part of the design. Now calculate the capacitor values lowpass coefficients into the custom design Coeffi- from the following formulae: cients table. 1 1 C11= ,C12= 2•π•R11•f (HPA) 2•π•R12•f (HPB) O O 156323fa 18

LTC1563-2/LTC1563-3 TYPICAL APPLICATIOUS 150kHz, 0.5dB Ripple, 4th Order Chebyshev with 10dB of DC Gain 20 5V LTC1563-2 10 0.1µF 1 LP V+ 16 R22 0 2 15 21k SA LPB –10 3 NC NC 14 VOUT B)–20 R31 R32 d R11 9.76k 45 INNCVA INNVBC 1132 12.7k GAIN (–30 24.3k R21 6 11 –40 VIN LPA SB 76.8k 7 10 R12 –50 AGND NC 21k –5V 8 V– EN 9 –60 –70 0.1µF 10k 100k 1M 1563 TA10 FREQUENCY (Hz) 1563 TA10a PACKAGE DESCRIPTIOU Dimensions in inches (millimeters) unless otherwise noted. GN Package 16-Lead Plastic SSOP (Narrow 0.150) (LTC DWG # 05-08-1641) .189 – .196* .045 ±.005 (4.801 – 4.978) .009 (0.229) 16 15 14 13 12 11 109 REF .254 MIN .150 – .165 .229 – .244 .150 – .157** (5.817 – 6.198) (3.810 – 3.988) .0165 ±.0015 .0250 BSC RECOMMENDED SOLDER PAD LAYOUT 1 2 3 4 5 6 7 8 .015 ± .004 × 45°(cid:31) .0532 – .0688 .004 – .0098 (0.38 ± 0.10) (1.35 – 1.75) (0.102 – 0.249) .007 – .0098 0° – 8° TYP (0.178 – 0.249) .016 – .050 .008 – .012 .0250 GN16 (SSOP) 0204 (0.406 – 1.270) (0.203 – 0.305) (0.635) NOTE: TYP BSC 1. CONTROLLING DIMENSION: INCHES INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) 3. DRAWING NOT TO SCALE *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 156323fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 19 However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LTC1563-2/LTC1563-3 TYPICAL APPLICATIOUS Single Supply, 10kHz, Bandpass Filter Maximum Fcenter = 120kHz (–3dB Bandwidth = Fcenter/10) Frequency Response V+ 3 LTC1563-2 0.1µF 1 LP V+ 16 R3 0 2 SA LPB 15 200k –3 R1 3 NC NC 14 VOUT –6 31.6k 4 13 VIN 4.R929k 56 INNCVA INNVCB 1121 2R004k AIN (dB)–1–29 LPA SB G 7 AGND NC 10 –15 0.1µF 8 V– EN 9 –18 –21 –24 1563 TA11 5 7.5 10 12.5 15 17.5 20 GRA2 I=N 4A.9T9 fkCENTER = 3 1R . 16 k MAXIMUM GAIN = 120kHz/fCENTER FREQUENCY (kHz) R3 = R4 = R 1563 TA11a R = 1021 fCENTER • (fCENTER2 + 5 • 1011) Single Supply, 100kHz, Elliptic Lowpass Filter Maximum Fcutoff = 120kHz Frequency Response VOUT 6 LTC1563-2 V+ 0 0.1µF R1 1 LP V+ 16 R5 –6 VIN 32.4k 2 SA LPB 15 32.4k –12 R3 3 NC NC 14 –18 R4 1R52k 45 INNCVA INNVCB 1132 AIN (dB) ––3204 32.4k 32.4k 6 LPA SB 11 G –36 7 10 R6 AGND NC 21k –42 0.1µF 8 V– EN 9 C27INpF –48 –54 –60 1K 10K 100K 1M FREQUENCY (Hz) 1563 TA12 PASSBAND GAIN = 0dB 1563 TA12a STOPBAND ATTENUATION = 26dB AT 1.5X fCUTOFF CIN = 27pF R2 = R4 = R5 = R1 R1 = 3 . 2 4 • 1 0 9 R3 = R 1 R6 = R 1 fCUTOFF 2.16 1.54 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1560-1 5-Pole Elliptic Lowpass, f = 1MHz/0.5MHz No External Components, SO-8 C LTC1562 Universal Quad 2-Pole Active RC 10kHz < f < 150kHz O LTC1562-2 Universal Quad 2-Pole Active RC 20kHz < f < 300kHz O LTC1569-6 Low Power 10-Pole Delay Equalized Elliptic Lowpass f < 80kHz, One Resistor Sets f , SO-8 C C LTC1569-7 10-Pole Delay Equalized Elliptic Lowpass f < 256kHz, One Resistor Sets f , SO-8 C C LTC1565-31 650kHz Continuous Time, Linear Phase Lowpass f = 650kHz, Differential In/Out C LTC1568 Very Low Noise 4th Order Filter Building Block f < 10MHz C 156323fa 20 Linear Technology Corporation LT 1205 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2005

Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: A nalog Devices Inc.: LTC1563-2CGN#TR LTC1563-3CGN#TRPBF LTC1563-2IGN#PBF LTC1563-3IGN#TRPBF LTC1563-2IGN#TR LTC1563-2CGN LTC1563-2IGN#TRPBF LTC1563-3IGN LTC1563-2CGN#TRPBF LTC1563-3CGN#TR LTC1563- 2IGN LTC1563-2CGN#PBF LTC1563-3IGN#PBF LTC1563-3IGN#TR LTC1563-3CGN#PBF LTC1563-3CGN