LT1316 Micropower DC/DC Converter with Programmable Peak Current Limit FEATURES DESCRIPTIOUN n Precise Control of Peak Switch Current The LT®1316 is a micropower step-up DC/DC converter n Quiescent Current: that operates from an input voltage as low as 1.5V. A 33m A in Active Mode programmable input current limiting function allows pre- 3m A in Shutdown Mode cise control of peak switch current. Peak switch current n Low-Battery Detector Active in Shutdown can be set to any value between 30mA and 500mA by n Low Switch V : 300mV at 500mA adjusting one resistor. This is particularly useful for CESAT n 8-Lead MSOP and SO Packages DC/DC converters operating from high source impedance n Operates with V as Low as 1.5V inputs such as lithium coin cells or telephone lines. IN n Logic Level Shutdown Pin The fixed off-time, variable on-time regulation scheme results in quiescent current of only 33m A in active mode. APPLICATIOUNS Quiescent current decreases to 3m A in shutdown with the low-battery detector still active. n Battery Backup The LT1316 is available in 8-lead MSOP and SO packages. n LCD Bias n Low Power –48V to 5V/3.3V Converters , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIONU 2-Cell to 5V Step-Up Converter Efficiency vs Load Current L1(cid:13) 47m H D1 5V(cid:13) 90 R1(cid:13) 50mA 3.3VIN 6 5 1M(cid:13) 7 VIN SW 8 1% 2.5VIN SHDN FB 2 CELLS + C471m(cid:13) F LT1316 + C472m(cid:13) F Y (%) 80 1.8VIN 2 1 NC NC LBI LBO NC E RSET GND R2(cid:13) FICI 3 4 324k(cid:13) EF 70 1% R5(cid:13) 10k(cid:13) 1% D1: MOTOROLA MBR0520L(cid:13) 60 L1: SUMIDA CD43-470 1316 TA01 0.1 1 10 100 LOAD CURRENT (mA) 1316 TA02 1

LT1316 ABSOLUTE WMAXIWMUWM RATINUGS PACKAGE/ORDER IUNFORWMATIOUN V Voltage .............................................................. 12V IN ORDER PART SW Voltage............................................... –0.4V to 30V TOP VIEW NUMBER FB Voltage ..................................................... V + 0.3V LBO(cid:13) 1(cid:13) 8(cid:13)FB(cid:13) IN LBI(cid:13) 2(cid:13) 7(cid:13)SHDN(cid:13) RSET Voltage............................................................. 5V RSET(cid:13) 3(cid:13) 6(cid:13)VIN(cid:13) LT1316CMS8 GND 4 5SW SHDN Voltage............................................................ 6V LBI Voltage................................................................V MS8 PACKAGE(cid:13) MS8 PART MARKING IN 8-LEAD PLASTIC MSOP(cid:13) LBO Voltage............................................................. 12V (cid:13) TJMAX = 125(cid:176)C, q JA = 160(cid:176)C/W LTCD Maximum Switch Current................................... 750mA Maximum Junction Temperature......................... 125(cid:176) C ORDER PART TOP VIEW Operating Temperature Range NUMBER Commercial.............................................0(cid:176) C to 70(cid:176) C LBO(cid:13) 1(cid:13) 8(cid:13) FB(cid:13) Extended Commercial (Note 1).......... –40(cid:176) C to 85(cid:176) C LBI(cid:13) 2(cid:13) 7(cid:13) SHDN(cid:13) LT1316CS8 LT1316IS8 Industrial (Note 2).............................. –40(cid:176) C to 85(cid:176) C RSET(cid:13) 3(cid:13) 6(cid:13) VIN(cid:13) Storage Temperature Range................. –65(cid:176) C to 150(cid:176) C GND 4 5(cid:13) SW S8 PART MARKING Lead Temperature (Soldering, 10 sec)..................300(cid:176) C S8 PACKAGE(cid:13) (cid:13) 8-LEAD PLASTIC SO(cid:13) 1316 (cid:13) TJMAX = 125(cid:176)C, q JA = 120(cid:176)C/W 1316I Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS Commercial grade 0(cid:176) C to 70(cid:176) C, Industrial grade –40(cid:176) C to 85(cid:176) C, V = 2V, V = V , T = 25(cid:176) C unless otherwise noted. (Notes 1, 2) IN SHDN IN A PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage 1.5 1.65 V Maximum Operating Voltage 12 V Quiescent Current V = 2V, Not Switching 33 45 m A SHDN l 50 m A Quiescent Current in Shutdown V = 0V, V = 2V l 3 5 m A SHDN IN V = 0V, V = 5V l 7 10 m A SHDN IN FB Pin Bias Current l 3 30 nA Line Regulation V = 1.8V to 12V l 0.04 0.15 %/V IN LBI Input Threshold Falling Edge l 1.1 1.17 1.25 V LBI Pin Bias Current l 3 20 nA LBI Input Hysteresis l 35 65 mV LBO Output Voltage Low I = 500m A l 0.2 0.4 V SINK LBO Output Leakage Current LBI = 1.7V, LBO = 5V l 0.01 0.1 m A SHDN Input Voltage High l 1.4 V SHDN Input Voltage Low l 0.4 V SHDN Pin Bias Current V = 5V l 2 5 m A SHDN V = 0V l –1 –3 m A SHDN 2

LT1316 ELECTRICAL CHARACTERISTICS Commercial grade 0(cid:176) C to 70(cid:176) C, Industrial grade –40(cid:176) C to 85(cid:176) C, V = 2V, V = V , T = 25(cid:176) C unless otherwise noted. (Notes 1, 2) IN SHDN IN A PARAMETER CONDITIONS MIN TYP MAX UNITS Switch OFF Time FB > 1V 1.4 2.0 2.6 m s l 1.1 3.0 m s FB < 1V 3.4 m s Switch ON Time Current Limit Not Asserted 4.4 6.3 8.2 m s 1V < FB < 1.2V l 3.4 9.5 m s Maximum Duty Cycle Current Limit Not Asserted 74 76 90 % 1V < FB < 1.2V l 73 90 % Switch Saturation Voltage I = 0.5A l 0.30 0.4 V SW I = 0.1A l 0.06 0.15 V SW Switch Leakage Switch Off, V = 5V l 0.1 5 m A SW Commercial grade 0(cid:176) C to 70(cid:176) C, V = 2V, V = V , T = 25(cid:176) C unless otherwise noted. IN SHDN IN A FB Comparator Trip Point l 1.21 1.23 1.25 V Peak Switch Current R = 27.4k, T = 25(cid:176) C 90 100 110 mA SET A R = 27.4k, T =0(cid:176) C 90 100 115 mA SET A R = 27.4k, T = 70(cid:176) C 70 90 110 mA SET A R = 10K l 250 290 340 mA SET R = 121k 25 mA SET Industrial grade –40(cid:176) C to 85(cid:176) C, V = 2V, V = V , T = 25(cid:176) C unless otherwise noted. IN SHDN IN A FB Comparator Trip Point l 1.205 1.23 1.255 V Peak Switch Current R = 27.4k, l 70 100 125 mA SET R = 10k l 200 290 370 mA SET The l denotes specifications which apply over the specified temperature over the –40(cid:176) C to 85(cid:176) C temperature range by design or correlation, but range. are not production tested. Note 1: C grade device specifications are guaranteed over the 0(cid:176) C to 70(cid:176) C Note 2: I grade device specifications are guaranteed over the –40(cid:176) C to temperature range. In addition, C grade device specifications are assured 85(cid:176) C temperature range. TYPICAL PERFORWMANUCE CHARACTERISTICS Load Transient Response Burst ModeTM Operation VOUT VOUT 100mV/DIV 100mV/DIV AC COUPLED AC COUPLED 50mA VSW 5V/DIV ILOAD INDUCTOR CURRENT 0mA 200mA/DIV 1316 G01 1316 G02 Burst Mode IS A TRADEMARK OF LINEAR TECHNOLOGY CORPORATION. 3

LT1316 TYPICAL PERFORWMANUCE CHARACTERISTICS Switch Saturation Voltage LBI Pin Bias Current vs Switch Current vs Temperature Off-Time vs Temperature 500(cid:13) 8(cid:13) 4(cid:13) V) 75°C m AGE ( 400(cid:13) A) 6(cid:13) 3(cid:13) T n VOL 300(cid:13) 100°C NT ( µs) TURATION 200(cid:13) 25°–C40°C PIN CURRE 4(cid:13) OFF-TIME ( 2(cid:13) SA BI H L 2(cid:13) 1(cid:13) TC 100(cid:13) WI S 0 0 0 0 100 200 300 400 500 600 700 800 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 SWITCH CURRENT (mA) TEMPERATURE (°C) TEMPERATURE (°C) 1316 G03 1316 G04 1316 G05 Maximum On-Time vs Temperature Quiescent Current vs Temperature Feedback Voltage vs Temperature 8(cid:13) 36(cid:13) 1.240(cid:13) 34(cid:13) µMAXIMUM ON-TIME (s) 76(cid:13)(cid:13) µUIESCENT CURRENT (A) 3320(cid:13)(cid:13) FEEDBACK VOLTAGE (V)111...222332505(cid:13)(cid:13)(cid:13) Q 28(cid:13) 5 26 1.220 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 1316 G06 1316 G07 1316 G08 FB Pin Bias Current Shutdown Pin Bias Current Peak Switch Current vs Temperature vs Shutdown Pin Voltage vs Temperature 4(cid:13) 4(cid:13) 1000 RSET = 4.84k FB PIN BIAS CURRENT (nA) 32(cid:13)(cid:13) µSHUTDOWN PIN CURRENT (A) 3210(cid:13)(cid:13)(cid:13)(cid:13) PEAK SWITCH CURRENT (mA) 100 RRRSSSEETET T == = 29 1770..43kkk 1 –1 10 –50 –25 0 25 50 75 100 0 1 2 3 4 5 6 –50 –25 0 25 50 75 100 TEMPERATURE (°C) SHUTDOWN PIN VOLTAGE (V) TEMPERAT(cid:13)URE (°C) 1316 G11 1316 G09 1316 G10 (cid:13) 4

LT1316 PIUN FUUNCTIOUNS LBO (Pin 1): Low-Battery Detector Output. Open collector SW (Pin 5): Collector of NPN Power Transistor. Keep can sink up to 500m A. Low-battery detector remains active traces at this pin as short as possible. in shutdown mode. V (Pin 6): Input Supply. Must be bypassed close to the IN LBI (Pin 2): Low-Battery Detector Input. When voltage at pin. this pin drops below 1.17V, LBO goes low. SHDN (Pin 7): Shutdown. Ground this pin to place the part R (Pin 3): A resistor between R and GND programs in shutdown mode (only the low-battery detector remains SET SET peak switch current. The resistor value should be between active). Tie to a voltage between 1.4V and 6V to enable the 3k and 150k. Do not float or short to ground. This is a high device. SHDN pin is logic level and need only meet the impedance node. Keep traces at this pin as short as logic specification (1.4V for high, 0.4V for low). possible. Do not put capacitance at this pin. FB (Pin 8): Feedback Pin. Reference voltage is 1.23V. GND (Pin 4): Ground. Connect directly to ground plane. Connect resistive divider tap here. Minimize trace area at FB. Set V according to: V = 1.23V(1 + R1/R2). OUT OUT BLOCK DIAGRAW D1 L1 VIN VOUT C1 R1 LB0 VIN SW 1 6 5 LBI 2 + 1.5V(cid:13) A3 UNDERVOLTAGE(cid:13) LOCKOUT – R3 = 10R4 R4 FB – 8 1.17V + – A1 R2 + A2 VREF(cid:13) 1.23V OSCILLATOR(cid:13) 0.5V + 6.3m s ON(cid:13) DRIVER 2m s OFF A4 – Q2(cid:13) · 1 Q1(cid:13) · 200 3 4 7 RSET GND SHDN 1316 F01 R5 Figure 1. LT1316 Block Diagram 5

LT1316 APPLICATIOUNS INUFORWMATIOUN Table 1 simplifies component selection for commonly During the portion of the switch cycle when Q1 is turned used input and output voltages. The methods used in off, current is forced through D1 to C1 causing output determining these values are discussed in more detail later voltage to rise. This switching action continues until in this data sheet. output voltage rises enough to overcome A1’s hysteresis. V can be set using the equation: Peak switch current is set by a resistor from the R pin OUT SET to ground. Voltage at the R pin is forced to 0.5V by A4 SET VOUT and is used to set up a constant current through R5. This ) ) current also flows through R3 which sets the voltage at the R1 R2 + R1(cid:13) positive input of comparator A2. When Q1 turns on, the VOUT = 1.23 R2 FB SW pin goes low and current ramps up at the rate V /L. R2 IN Current through Q2 is equal to Q1’s current divided by 200. 1316 EQF01 When current through Q2 causes the voltage drop across Table 1. R Resistor and Inductor Values R4 and R3 to be equal, A2 changes state and resets the SET LOAD R PEAK SWITCH oscillator, causing Q1 to turn off. Shutdown is accom- SET VIN VOUT CURRENT RESISTOR INDUCTOR CURRENT plished by grounding the SHDN pin. 2 5 10mA 36.8k 100m H 80mA The low-battery detector A3 has its own 1.17V reference 2 5 25mA 18.2k 68m H 165mA and is always on. The open collector output device can sink 2 5 50mA 10k 47m H 320mA up to 500m A. Approximately 35mV of hysteresis is built 2 5 75mA 6.81k 33m H 500mA into A3 to reduce “buzzing” as the battery voltage reaches 5 12 100mA 6.81k 82m H 490mA the trip level. 5 28 1mA 75k 100m H 56mA 5 28 5mA 22.1k 100m H 140mA Current Limit 5 28 10mA 10k 100m H 270mA During active mode when the part is switching, current in the inductor ramps up each switch cycle until reaching a Operation preprogrammed current limit. This current limit value To understand operation of the LT1316, first examine must be set by placing the appropriate resistor from the Figure 1. Comparator A1 monitors FB voltage which is R pin to ground. This resistance value can be found by SET V divided down by resistor divider network R1/R2. OUT using Figure 3 to locate the desired DC current limit and When voltage at the FB pin drops below the reference voltage (1.23V), A1’s output goes high and the oscillator 1000 is enabled. The oscillator has an off-time fixed at 2m s and an on-time limited to 6.3m s. Power transistor Q1 is cycled on and off by the oscillator forcing current through the A) m inductor to alternately ramp up and down (see Figure 2). MIT ( LI T 100 N VOUT RE AC COUPLED UR 200mV/DIV C C D VSW 5V/DIV INDUCTOR 10 CURRENT 10 100 100mA/DIV RSET (kW ) 1316 F03 Figure 3. DC Current Limit vs R Resistor 10m s/DIV 1316 F02 SET Note: DC Current is the Peak Switch Current if the Power Figure 2. Switching Waveforms Transistor had Zero Turn-Off Delay 6

LT1316 APPLICATIOUNS INUFORWMATIOUN then adding in the amount of overshoot that will occur due V – V + V (cid:13) OUT IN D to turn-off delay of the power transistor. This turn-off L = 0.4(I ) (tOFF) (2) PEAK delay is approximately 300ns. where t = 2m s and V = 0.4V. Peak switch current = DC current limit from graph + OFF D V /L(turn-off delay) As a result of equations 1 and 2, ripple current during IN switching will be 40% of the peak current (see Figure 2). Example: Using these equations at the specified I , the part is OUT delivering approximately 60% of its maximum output Set peak switch current to 100mA for: V = 2V, IN L = 33m H power. In other words, the part is operating on a 40% reserve. This is a safe margin to use and can be decreased Overshoot = V /L(turn-off delay) = (2/33m H)(300ns) IN if input voltage and output current are tightly controlled. = 18.2mA For some applications, this recommended inductor size Refer to R graph and locate SET (100mA – 18.2mA) » 82mA may be too large. Inductance can be reduced but available output power will decrease. Also, ripple current during R » 33k SET switching will increase and may cause discontinuous operation. Discontinuous operation occurs when Calculating Duty Cycle inductor current ramps down to zero at the end of each For a boost converter running in continuous conduction switch cycle (see Figure 4). Shown in Figure 5 is minimum mode, duty cycle is constrained by VIN and VOUT according inductance vs peak current for the part to remain in to the equation: continuous mode. V – V + V (cid:13) DC = OUT IN D 0mA INDUCTOR V – V + V OUT SAT D CURRENT 100mA/DIV where V = diode voltage drop » 0.4V and V = switch D SAT saturation voltage » 0.2V. SW PIN If the duty cycle exceeds the LT1316’s minimum specified 5V/DIV duty cycle of 0.73, the converter cannot operate in con- 2m s/DIV 1316 F04 tinuous conduction mode and must be designed for discontinuous mode operation. Figure 4. Discontinuous Mode Operation 1000 Inductor Selection and Peak Current Limit for Continuous Conduction Mode H) 5V TO 18V Peak current and inductance determine available output E FOR (cid:13)mTION ( 5V TO 12V CA power. Both must be chosen properly. If peak current or TANPER 2V TO 5V CO inductance is increased, output power increases. Once DUDE 100 NO ocuurtrpeuntt p coawne br eo rs ectu rbrye ntht ea nfdo lldouwtyin cgy celqeu aarteio knn, oawssnu, mpeinagk NIMUM INOUS M continuous mode operation: MINTI O C 2(I ) (cid:13) 10 OUT 10 100 1000 I = (1) PEAK 1 – DC PEAK CURRENT (mA) 1316 F05 Figure 5. Minimum Inductance vs Peak Current Inductance can now be calculated using the peak current: for Continuous Mode Operation 7

LT1316 APPLICATIOUNS INUFORWMATIOUN Discontinuous Mode Operation 2(I )(cid:13) 2(10mA)(cid:13) OUT 2. I = = = 58mA PEAK A boost converter with a high V :V ratio operates with 1 – DC 1 – 0.654 OUT IN a high duty cycle in continuous mode. For duty cycles 3. Find L exceeding the LT1316’s guaranteed minimum specifica- ) ) tion of 0.73, the circuit will need to be designed for V – V + V (cid:13) L = OUT IN D t discontinuous operation. Additionally, very low peak cur- OFF 0.4(I ) PEAK rent limiting below 50mA may necessitate operating in this ) ) mode unless high inductance values are acceptable. When = 5 – 2 + 0.4(cid:13) 2m s operating in discontinuous mode, a different equation 0.4(58mA) governs available output power. For each switch cycle, the = 293m H inductor current ramps down to zero, completely releas- ing the stored energy. Energy stored in the inductor at any 4. Find R resistor SET time is equal to 1/2 LI2. Because this energy is released ) ) each cycle, the equation for maximum power out is: V (cid:13) Overshoot = IN 300ns L ) ) POUT(MAX) )= 1/2L(IPEAK2)f ) 2(cid:13) = = 1.8mA 1(cid:13) 330m H Where f = I (L)(cid:13)(cid:13) PEAK + t VIN – VSAT OFF Find RSET from Figure 3 for 58mA – 1.8mA = 56.2mA R » 47k SET When designing for very low peak currents (<50mA), the inductor size needs to be large enough so that on-time is Design Example 2 a least 1m s. On-time can be calculated by the equation: Requirements: V = 3.3V, V = 28V and I = 5mA. IN OUT LOAD ) ) I • L(cid:13) 1. Find duty cycle: PEAK On-Time = ) ) ) ) (V – V ) IN SAT DC = VOUT – VIN + VD(cid:13) = 28 – 3.3 + 0.4(cid:13) = 0.89 V – V + V 28 – 0.2 + 0.4 where V = 0.2V. OUT SAT D SAT Also, at these low current levels, current overshoot due to Because duty cycle exceeds LT1316 minimum specifi- power transistor turn-off delay will be a significant portion cation of 73%, the circuit must be designed for discon- of peak current. Increasing inductor size will keep this to tinuous operation. a minimum. 2. Find P OUT(MAX) Design Example 1 Multiply POUT by 1.4 to give a safe operating margin P = P (1.4) = (5mA)(28V)(1.4) = 0.196W Requirements: V = 2V, V = 5V and I = 10mA. OUT(MAX) OUT IN OUT LOAD 3. Set the on-time to the data sheet minimum of 3.4m s and 1. Find duty cycle ) ) ) ) find L DC = VOUT – VIN + VD(cid:13) = 5 – 2 + 0.4(cid:13) = 0.654 (t 2)(V – V )2(cid:13) V – V + V 5 – 0.2 + 0.4 L = ON IN SAT OUT SAT D 2P (t + t ) OUT(MAX) ON OFF Because duty cycle is less than the LT1316 minimum (3.4m s2)(3.3 – 0.2)2(cid:13) specification (0.73), the circuit can be designed for = = 52m H 2(0.196W)(3.4m s + 2m s) continuous operation. 8

LT1316 APPLICATIOUNS INUFORWMATIOUN 4. Find I for 3.4m s on-time For through-hole applications Sanyo OS-CON capacitors PEAK offer extremely low ESR in a small package size. If peak t (V – V )(cid:13) 3.4m s(3.3 – 0.2)(cid:13) IPEAK = ON INL SAT = 52m H switch current is reduced using the RSET pin, capacitor requirements can be eased and smaller, higher ESR units = 0.202A can be used. Ordinary generic capacitors can generally be used when peak switch current is less than 100mA, 5. Find R resistor SET although output voltage ripple may increase. ) ) V (cid:13) Overshoot = IN 300ns Diodes L ) ) Most of the application circuits on this data sheet specify 3.3(cid:13) = 300ns = 19mA the Motorola MBR0520L surface mount Schottky diode. 52m H This 0.5A, low drop diode suits the LT1316 well. In lower current applications, a 1N4148 can be used although Find RSET from Figure 3 for 0.202A – 19mA = 0.183A efficiency will suffer due to the higher forward drop. This R » 13k effect is particularly noticeable at low output voltages. For SET higher output voltage applications, such as LCD bias These discontinuous mode equations are designed to generators, the extra drop is a small percentage of the minimize peak current at the expense of inductor size. If output voltage so the efficiency penalty is small. The low smaller inductors are desired peak current must be cost of the 1N4148 makes it attractive wherever it can be increased. used. In through-hole applications the 1N5818 is the all around best choice. Capacitor Selection Lowering Output Ripple Voltage Low ESR (Equivalent Series Resistance) capacitors should be used at the output of the LT1316 to minimize output To obtain lower output ripple voltage, a small feedforward ripple voltage. High quality input bypassing is also capacitor of about 50pF to 100pF may be placed from required. For surface mount applications AVX TPS series V to FB as detailed in Figure 6. Ripple voltages with OUT tantalum capacitors are recommended. These have been and without the added capacitor are pictured in Figures specifically designed for switch mode power supplies and 7 and 8. have low ESR along with high surge current ratings. SHUTDOWN L1(cid:13) 47m H D1 VOUT R1(cid:13) + C1(cid:13) VIN SW 11M%(cid:13) 100pF 47m F SHDN FB + 2 (cid:13) 47m F LT1316 R2(cid:13) CELLS 324k(cid:13) 1% RSET GND 10k 1316 F06 Figure 6. 2-Cell to 5V Step-Up Converter with Reduced Output Ripple Voltage 9

LT1316 APPLICATIOUNS INUFORWMATIOUN 100mVV/DOUIVT VOUT 100mV/DIV AC COUPLED AC COUPLED 100mA/DIIVL IL 100mA/DIV 100m s/DIV 1316 F07 50m s/DIV 1316 F08 Figure 7. Switching Waveforms for the Circuit Figure 8. By Adding C1, Output Ripple Voltage Shown in Figure 7 Without C1. The Output Ripple is Reduced to Less Than 80mV P-P Voltage is Approximately 140mV P-P Layout/Input Bypassing 1m F ceramic capacitor acts to smooth voltage spikes at switch turn-on and turn-off. If the power source is far away The LT1316’s high speed switching mandates careful from the IC, inductance in the power source leads results attention to PC board layout. Suggested component place- in high impedance at high frequency. A local high capaci- ment is shown in Figure 9. The input supply must have low tance bypass is then required to restore low impedance at impedance at AC and the input capacitor should be placed the IC. as indicated in the figure. The value of this capacitor depends on how close the input supply is to the IC. In Low-Battery Detector situations where the input supply is more than a few inches away from the IC, a 47m F to 100m F solid tantalum The LT1316 contains an independent low-battery detector bypass capacitor is required. If the input supply is close to that remains active when the device is shut down. This the IC, a 1m F ceramic capacitor can be used instead. The detector, actually a hysteretic comparator, has an open LT1316 switches current in pulses up to 0.5A, so a low collector output that can sink up to 500m A. The compara- impedance supply must be available. If the power source tor also operates below the switcher’s undervoltage lock- (for example, a 2 AA cell battery) is within 1 or 2 inches of out threshold, operating until VIN reaches approximately the IC, the battery itself provides bulk capacitance and the 1.4V. 1 8 2 LT1316 7 3 6 L VIN 4 5 RSET + CIN GND D COUT + 1316 F09 VOUT Figure 9. Suggested PC Layout 10

LT1316 TYPICAL APPLICATIONUS N Nonisolated –48V to 5V Flyback Converter D1(cid:13) VOUT(cid:13) T1(cid:13) 1N5817 5V(cid:13) 10:1:1 50mA 3 2 + C3(cid:13) L1 L3 47m F 4 1 D2(cid:13) 1N4148 7 L2 D3(cid:13) 1N4148 C2(cid:13) R1(cid:13) 6 0.022m F 1.3M VA Q1 + R4(cid:13) C4(cid:13) 2M 6 5 47m F C1(cid:13) 7 VIN SW 0.1m F SHDN Q2(cid:13) R7(cid:13) T1(cid:9)=(cid:9)DALE LPE-4841-A313 (605-665-9301) (cid:13) R1.23(cid:13)0M(cid:13) 1 LB0 LT1316 FB 8 MPSA92 432k, 1% (cid:9)(cid:9) (cid:9)(cid:9) LRPDRSI(:O 2Nm): H4(cid:13).3Ω AT VGS = 2.5V(cid:13) R(cid:9)6, Q2,R7 MUST BE PLACED NEXT(cid:13) Q3(cid:13) 1% 2 TO THE FB PIN(cid:13) 2N3904 LBI R6(cid:13) RSET GND 112%1k(cid:13) IVININ = = 1 4980Vµ,A IL WOAHDE =N (cid:13)1mA(cid:13) 3 4 (cid:13) R3(cid:13) R5(cid:13) 604k(cid:13) 69.8k(cid:13) 1% 1% – 48V 1316 • TA03 Efficiency vs Load Current 90 80 36VIN %) Y ( 70 C N FICIE 60 48VIN EF 72VIN 50 40 1 10 100 LOAD CURRENT (mA) 1316 TA04 11

LT1316 TYPICAL APPLICATIONUS N Positive-to-Negative Converter for LCD Bias L1(cid:13) D1(cid:13) SHUTDOWN 33m H MMBD914 VIN C2(cid:13) C3(cid:13) 0.01µF(cid:13) 100pF(cid:13) R1(cid:13) 6 5 50V 50V 3.3M VIN SW 7 8 2.2M CONTRAST(cid:13) SHDN FB + C1(cid:13) ADJUST 2 CELLS 33m F(cid:13) LT1316 R2(cid:13) 210k 10V + C4(cid:13) RSET GND 1m F(cid:13) 3 4 35V + C5(cid:13) C6(cid:13) R3(cid:13) D2(cid:13) 2.2µF(cid:13) 0.33µF(cid:13) 15k MMBD914 35V 50V VOUT(cid:13) –20V(cid:13) 6mA D3(cid:13) C4: SPRAGUE 293D105X9035B2T(cid:13) MBR0530L C5: SPRAGUE 293D225X0035B2T(cid:13) L1: SUMIDA CD43-330(cid:13) (cid:13) 1316 TA06 Battery-Powered Solenoid Driver 47Lm1H(cid:13) BAT-85 VCAP ZTX949 VIN 47k 1N4148 470k 6 5 6.8M VIN SW 1 2 + C1(cid:13) LBO LBI + C4720(cid:13) µF(cid:13) 1.3k 2 CELLS 47m F(cid:13) LT1316 5k 50V SOLENOID 16V 7 8 SHDN FB RSET GND 324K 50k 3 4 2N3904 VENERGIZE 20k 1316 TA08 C1: AVX TPS 47µF, 16V(cid:13) CAP(cid:13) SHUTDOWN C2: SANYO 50MV470GX(cid:13) GOOD L1: SUMIDA CD43-470 When Solenoid Is Energized (V High) Peak Input Current ENERGIZE Remains Low and Controlled, Maximizing Battery Life VENERGIZE 5V/DIV IL1 200mA/DIV VCAP 10V/DIV CAP GOOD 5V/DIV 500ms/DIV 1316 TA09 12

LT1316 TYPICAL APPLICATIONUS N Super Cap Backup Supply R1(cid:13) READY 10k 1M L1(cid:13) D1(cid:13) 47m H 0.5A CONNECT TO(cid:13) MAIN SUPPLY(cid:13) 5V(cid:13) 6 5 6mA VIN SW 1.00M 1 LBO + C0.S1UFP(cid:13)(cid:13)+ C33INm(cid:13)F(cid:13) 2 LBI LT1316 1.00M 100pF + C33OmUFT(cid:13)(cid:13) 57.55WV(cid:13) 10V 357k 7 SHDN FB 8 10V RSET GND 324k 3 4 RSET(cid:13) 33k RUN 1316 TA10 CIN, COUT:(cid:13)TAJB330M010R(cid:13) D1:(cid:13)MBR0520LT3(cid:13) CSUP:(cid:13)PANASONIC EEC-S5R5V104(cid:13) L1:SUMIDA CD43-470 (cid:13)(cid:13) 50V to 6V Isolated Flyback Converter T1(cid:13) LPRI: 2mH(cid:13) 1N5817 (cid:13) +VIN(cid:13) 10:1:1 + 25V TO(cid:13) 3 2 50V + C1(cid:13) VOUT(cid:13) 100µF(cid:13) 6V/20mA(cid:13) 16V 75% EFFICIENCY 4 1 – 7 510k 1N4148 0.022m F(cid:13) Q1 100V(cid:13) CERAMIC 1N4148 6 2M 6 5 0.1m F 7 SHDNVIN SW 50k 1 8 1m F(cid:13) 1.30M(cid:13) LB0 LT1316 FB 16V(cid:13) 1% CERAMIC 2N3904 2 12.7k LBI 604k(cid:13) RSET GND C1 = SANYO OS-CON 100µF, 16V(cid:13) 1% 3 4 Q1 =(cid:9)ZETEX ZVN 4424A(cid:13) 69.8k(cid:13) T1(cid:9)=(cid:9)DALE LPE-4841-A313 (605-665-9301)(cid:13) 1% 1316 TA11 13

LT1316 TYPICAL APPLICATIONUS N LCD Bias Generator with Output Disconnect in Shutdown VBAT(cid:13) 1.6V TO 3.5V OPTIONAL CONNECTION 150k L1(cid:13) 22µH MBR0540LT1 VIN(cid:13) V17O.U1TV(cid:13) TO 19.8V(cid:13) 3.3V Q1 100pF(cid:13) 4mA 6 5 3.32M(cid:13) 50V(cid:13) + C1(cid:13) VIN SW 1% CERAMIC 22m F(cid:13) FB 8 6.3V LT1316 7 SHUTDOWN SHDN 232k(cid:13) + C2(cid:13) 0.33µF(cid:13) RSET GND 4.7M 1% 3.3µF(cid:13) 50V(cid:13) 35V CERAMIC 3 4 11k(cid:13) 1% 1316 TA12 C1: AVX TAJA226M006R(cid:13) VADJ(cid:13) C2: AVX TAJB335M035R(cid:13) (VOUT ADJUST)(cid:13) L1: MURATA LQH3C220K04(cid:13) 0V TO 3.3V Q1: MMBT3906LT3 Universal Serial Bus (USB) to 5V/100mA DC/DC Converter RB(cid:13) 100Ω L1(cid:13) VIN(cid:13) 33µH D1 VOUT(cid:13) 4V TO(cid:13) 5V(cid:13) Q1 7V 100mA 6 5 VIN SW 7 + C2(cid:13) + C3(cid:13) + C1(cid:13) SHDN 33µF(cid:13) 100pF R2(cid:13) 10µF(cid:13) 10m F(cid:13) LT1316 10V 1.00M 10V 10V 3 8 RSET FB GND R1(cid:13) R3(cid:13) 4 324k 10k 1316 TA13 C1: 10µF 10V AVX TAJB106M010(cid:13) C2: 33µF 10V AVX TPSC336M010(cid:13) C3: 10µF ALUMINUM ELECTROLYTIC(cid:13) D1: MBR0520LT1(cid:13) L1: 33µH SUMIDA CD43 (OR COILCRAFT DO1608)(cid:13) Q1: MPS1907A 14

LT1316 PACKAGE DESCRIPTIOUN Dimensions in inches (millimeter) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.118 – 0.004*(cid:13) (3.00 – 0.102) 8 7 6 5 0.192 – 0.004(cid:13) 0.118 – 0.004**(cid:13) (4.88 – 0.10) (3.00 – 0.102) 1 2 3 4 0.040 – 0.006(cid:13) 0.034 – 0.004(cid:13) (1.02 – 0.15) (0.86 – 0.102) 0.007(cid:13) 0° – 6° TYP (0.18) SEATING(cid:13) 0.021 – 0.006(cid:13) PLANE 0.012(cid:13) 0.006 – 0.004(cid:13) (0.53 – 0.015) (0.30)(cid:13) (0.15 – 0.102) 0.0256(cid:13) REF(cid:13) (0.65)(cid:13) (cid:13) TYP (cid:9) *(cid:9)DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, (cid:13) (cid:9)(cid:9) PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE(cid:13) (cid:9) **(cid:9)DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. (cid:13) (cid:9)(cid:9) INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE MSOP (MS8) 1197 S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.189 – 0.197*(cid:13) (4.801 – 5.004) 8 7 6 5 0.228 – 0.244(cid:13) 0.150 – 0.157**(cid:13) (5.791 – 6.197) (3.810 – 3.988) 1 2 3 4 0.010 – 0.020(cid:13) · 45(cid:176) 0.053 – 0.069(cid:13) (0.254 – 0.508) (1.346 – 1.752) 0.004 – 0.010(cid:13) 0.008 – 0.010(cid:13) (0.203 – 0.254) 0°– 8° TYP (0.101 – 0.254) 0.016 – 0.050(cid:13) 0.014 – 0.019(cid:13) 0.050(cid:13) 0.406 – 1.270 (0.355 – 0.483) (1.270)(cid:13) *(cid:13)DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH (cid:13) TYP SO8 0996 (cid:13)SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE(cid:13) **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD (cid:13) FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE(cid:13) (cid:13) (cid:13) Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 15 However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of circuits as described herein will not infringe on existing patent rights.

LT1316 TYPICAL APPLICATIONUS N Low Profile 2 Cell-to-28V Converter for LCD Bias L1(cid:13) VIN 22m H D1 VOUT(cid:13) 28V(cid:13) 5mA 6 5 C4(cid:13) C3(cid:13) VIN SW 100pF(cid:13) 0.33µF(cid:13) SHUTDOWN 7 SHDN 4.32M 50V 50V 2 CELLS C101m(cid:13) F 1 LBI LT1316 FB 8 + C1m2(cid:13)F(cid:13) 2 35V LBO 204k RSET GND 3 4 10k 1316 TA05 C1: MURATA GRM235Y5V106Z010(cid:13) C2: SPRAGUE 293D105X9035B2T(cid:13) C3: 0.33µF CERAMIC, 50V(cid:13) C4: 100pF CERAMIC, 50V(cid:13) D1: BAT-54(cid:13) L1: MURATA LQH3C220K04(cid:13) (cid:13) Bipolar LCD Bias Supply L1(cid:13) VIN(cid:13) 47µH 1N914 2N3904 13V(cid:13) 3.3V TO(cid:13) 4.2V 6 5 1Cµ2F(cid:13)(cid:13)+ 22k 10k 0.5mA VIN SW 35V 100pF 1.00M 7 8 + C21261mV(cid:13) F(cid:13) SHRDSNETLT1316GNDFB + C13µ53V(cid:13)F(cid:13) 88.7k + C3.43(cid:13)m F(cid:13) 3 4 35V –15V(cid:13) 1.5mA 47k BAT54(cid:13) (BAT54 = TWO DIODES IN SOT23) · 2 1316 TA14 C1: AVX TAJB226M016R(cid:13) C2, C3: AVX TAJA105K035R(cid:13) C4: AVX TAJB335M035R(cid:13) L1: MURATA LQH3C470(cid:13) (cid:13) RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC®1163 Triple High Side Driver for 2-Cell Inputs 1.8V Minimum Input, Drives N-Channel MOSFETs LTC1174 Micropower Step-Down DC/DC Converter 94% Efficiency, 130m A I , 9V to 5V at 300mA Q LT1302 High Output Current Micropower DC/DC Converter 5V/600mA from 2V, 2A Internal Switch, 200m A I Q LT1304 2-Cell Micropower DC/DC Converter Low-Battery Detector Active in Shutdown, 5V at 200mA for 2 Cells LT1307 Single Cell Micropower 600kHz PWM DC/DC Converter 3.3V at 75mA from 1 Cell LTC1440/1/2 Ultralow Power Single/Dual Comparators with Reference 2.8m A I , Adjustable Hysteresis Q LTC1516 2-Cell to 5V Regulated Charge Pump 12m A I , No Inductors, 5V at 50mA from 3V Input Q LT1521 Micropower Low Dropout Linear Regulator 500mV Dropout, 300mA Current, 12m A I Q 16 Linear Technology Corporation 1316f LT/TP 0298 4K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 l (408) 432-1900 FAX: (408) 434-0507 l TELEX: 499-3977 l www.linear-tech.com ª LINEAR TECHNOLOGY CORPORATION 1997