UC1526A UC2526A UC3526A Regulating Pulse Width Modulator FEATURES DESCRIPTION • Reduced Supply Current The UC1526A Series are improved-performance pulse-width modu- lator circuits intended for direct replacement of equivalent non- “A” • Oscillator Frequency to 600kHz versions in all applications. Higher frequency operation has been • Precision Band-Gap Reference enhanced by several significant improvements including: a more ac- curate oscillator with less minimum dead time, reduced circuit de- • 7 to 35V Operation lays (particularly in current limiting), and an improved output stage • Dual 200mA Source/Sink Outputs with negligible cross-conduction current. Additional improvements include the incorporation of a precision, band-gap reference gener- • Minimum Output Cross-Conduction ator, reduced overall supply current, and the addition of thermal • Double-Pulse Suppression Logic shutdown protection. • Under-Voltage Lockout Along with these improvements, the UC1526A Series retains the protective features of under-voltage lockout, soft-start, digital cur- • Programmable Soft-Start rent limiting, double pulse suppression logic, and adjustable • Thermal Shutdown deadtime. For ease of interfacing, all digital control ports are TTL compatible with active low logic. • TTL/CMOS Compatible Logic Ports Five volt (5V) operation is possible for “logic level” applications by • 5 Volt Operation (VIN = VC = VREF = 5.0V) connecting VIN, VC and VREF to a precision 5V input supply. Consult factory for additional information. BLOCK DIAGRAM 6/93

UC1526A UC2526A UC3526A ABSOLUTE MAXIMUM RATINGS (Note 1, 2) RECOMMENDED OPERATING CONDITIONS Input Voltage (+VIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +40V (Note 3) Collector Supply Voltage (+VC) . . . . . . . . . . . . . . . . . . . . . +40V Input Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7V to +35V Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +5.5V Collector Supply Voltage . . . . . . . . . . . . . . . . . . +4.5V to +35V Analog Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +VIN Sink/Source Load Current (each output) . . . . . . . . 0 to 100mA Source/Sink Load Current (each output). . . . . . . . . . . . 200mA Reference Load Current. . . . . . . . . . . . . . . . . . . . . . 0 to 20mA Reference Load Current. . . . . . . . . . . . . . . . . . . . . . . . . . 50mA Oscillator Frequency Range. . . . . . . . . . . . . . . . 1Hz to 600kHz Logic Sink Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15mA Oscillator Timing Resistor. . . . . . . . . . . . . . . . . . . 2kW to 150kW Power Dissipation at TA = +25°C (Note 2) . . . . . . . . . 1000mW Oscillator Timing Capacitor. . . . . . . . . . . . . . . . . 400pF to 20m F Power Dissipation at TC = +25°C (Note 2). . . . . . . . . . 3000mW Available Deadtime Range at 40kHz . . . . . . . . . . . . 1% to 50% Operating Junction Temperature. . . . . . . . . . . . . . . . . . +150°C Operating Ambient Temperature Range Storage Temperature Range. . . . . . . . . . . . . . -65°C to +150°C UC1526A. . . . . . . . . . . . . . . . . . . . . . . . . . . . -55°C to +125°C Lead Temperature (soldering, 10 seconds). . . . . . . . . . +300°C UC2526A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25°C to +85°C UC3526A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C Note 1:Values beyond which damage may occur. Note 2: Consult packaging Section of Databook for thermal Note 3:Range over which the device is functional and limitations and considerations of package. parameter limits are guaranteed. CONNECTION DIAGRAMS DIL-18, SOIC-18 (TOP VIEW) PLCC-20, LCC-20 PACKAGE PIN FUNCTION J or N Package, DW Package (TOP VIEW) FUNCTION PIN Q and L Packages N/C 1 +ERROR 2 -ERROR 3 COMP. 4 CSS 5 RESET 6 - CURRENT SENSE 7 + CURRENT SENSE 8 SHUTDOWN 9 RTIMING 10 CT 11 RD 12 SYNC 13 OUTPUT A 14 VC 15 N/C 16 GROUND 17 OUTPUT B 18 +VIN 19 VREF 20 2

UC1526A UC2526A UC3526A ELECTRICAL CHARACTERISTICS: +VIN = 15V, and over operating ambient temperature, unless otherwise specified TA = TJ. UC1526A / UC2526A UC3526A PARAMETER TEST CONDITIONS UNITS MIN TYP MAX MIN TYP MAX Reference Section (Note 4) Output Voltage TJ = +25°C 4.95 5.00 5.05 4.90 5.00 5.10 V Line Regulation +VIN = 7 to 35V 2 10 2 15 mV Load Regulation IL = 0 to 20mA 5 20 5 20 mV Temperature Stability Over Operating TJ (Note 5) 15 50 15 50 mV Total Output Voltage Over Recommended Operating 4.90 5.00 5.10 4.85 5.00 5.15 V Range Conditions Short Circuit Current VREF = 0V 25 50 100 25 50 100 mA Under-Voltage Lockout RESET Output Voltage VREF = 3.8V 0.2 0.4 0.2 0.4 V VREF = 4.7V 2.4 4.7 2.4 4.8 V Oscillator Section (Note 6) Initial Accuracy TJ = +25°C – 3 – 8 – 3 – 8 % Voltage Stability +VIN = 7 to 35V 0.5 1 0.5 1 % Temperature Stability Over Operating TJ (Note 5) 2 6 1 3 % Minimum Frequency RT = 150kW , CT = 20m F (Note 5) 1 1 Hz Maximum Frequency RT = 2kW , CT = 470pF 550 650 kHz Sawtooth Peak Voltage +VIN = 35V 3.0 3.5 3.0 3.5 V Sawtooth Valley Voltage +VIN =7V 0.5 1.0 0.5 1.0 V SYNC Pulse Width TJ = 25°C, RL = 2.7kW to VREF 1.1 1.1 m s Error Amplifier Section (Note 7) Input Offset Voltage RS £ 2kW 2 5 2 10 mV Input Bias Current -350 -1000 -350 -2000 nA Input Offset Current 35 100 35 200 nA DC Open Loop Gain RL ‡ 10MW 64 72 60 72 dB HIGH Output Voltage VPIN 1 - VPIN 2 ‡ 150mV, ISOURCE = 100m A 3.6 4.2 3.6 4.2 V LOW Output Voltage VPIN 2 - VPIN 1 ‡ 150mV, ISINK = 100m A 0.2 0.4 0.2 0.4 V Common Mode Rejection RS £ 2kW 70 94 70 94 dB Supply Voltage Rejection +VIN = 12 to 18V 66 80 66 80 dB PWM Comparator (Note 6) Minimum Duty Cycle VCOMPENSATION = +0.4V 0 0 % Maximum Duty Cycle VCOMPENSATION = +3.6V 45 49 45 49 % Digital Ports (SYNC, SHUTDOWN, and RESET) HIGH Output Voltage ISOURCE = 40m A 2.4 4.0 2.4 4.0 V LOW Output Voltage ISINK = 3.6mA 0.2 0.4 0.2 0.4 V HIGH Input Current VIH = +2.4V -125 -200 -125 -200 m A LOW Input Current VIL = +0.4V -225 -360 -225 -360 m A Shutdown Delay From Pin 8, TJ = 25°C 160 160 ns Current Limit Comparator (Note 8) Sense Voltage RS £ 50W 90 100 110 80 100 120 mV Input Bias Current -3 -10 -3 -10 m A Shutdown Delay From pin 7, 100mV Overdrive, TJ = 25°C 260 260 ns Note 4:IL = 0mA. Note 7:VCM = 0 to +5.2V Note 5:Guaranteed by design, not 100% tested in production. Note 8:VCM = 0 to +12V. Note 6:FOSC = 40kHz, (RT = 4.12kW – 1%, CT = 0.01m F– 1%, Note 9:VC = +15V. RD = 0 W ). Note 10:VIN = +35V, RT = 4.12kW . 3

UC1526A UC2526A UC3526A ELECTRICAL CHARACTERISTICS:+VIN = 15V, and over operating ambient temperature, unless otherwise specified TA = TJ. UC1526A UC3526A PARAMETER TEST CONDITIONS UC2526A UNITS MIN TYP MAX MIN TYP MAX Soft-Start Section Error Clamp Voltage RESET = +0.4V 0.1 0.4 0.1 0.4 V CS Charging Current RESET = +2.4V 50 100 150 50 100 150 m A Output Drivers (Each Output) (Note 9) HIGH Output Voltage ISOURCE = 20mA 12.5 13.5 12.5 13.5 V ISOURCE = 100mA 12 13 12 13 V LOW Output Voltage ISINK = 20mA 0.2 0.3 0.2 0.3 V ISINK = 100mA 1.2 2.0 1.2 2.0 V Collector Leakage VC = 40V 50 150 50 150 m A Rise Time CL = 1000pF (Note 5) 0.3 0.6 0.3 0.6 m s Fall Time CL = 1000pF (Note 5) 0.1 0.2 0.1 0.2 m s Cross-Conduction Charge Per cycle, TJ = 25°C 8 8 nC Power Consumption (Note 10) Standby Current SHUTDOWN = +0.4V 14 20 14 20 mA Note 4:IL = 0mA. Note 5:Guaranteed by design, not 100% tested in production. Note 6:FOSC = 40kHz, (RT = 4.12kW – 1%, CT = 0.01m F– 1%, RD = 0 W ). Note 7:VCM = 0 to +5.2V Note 8:VCM = 0 to +12V. Note 9:VC = +15V. Note 10:VIN = +35V, RT = 4.12kW . Open Loop Test Circuit UC1526A 4

UC1526A UC2526A UC3526A APPLICATIONS INFORMATION Voltage Reference The reference regulator of the UC1526A is based on a precision band-gap reference, internally trimmed to – 1% accuracy. The circuitry is fully active at supply voltages above +7V, and provides up to 20mA of load current to external circuitry at +5.0V. In systems where additional current is required, an external PNP transistor can be used to boost the available current. A rugged low fre- quency audio-type transistor should be used, and lead Figure 2. Under-Voltage Lockout Schematic lengths between the PWM and transistor should be as Soft-Start Circuit short as possible to minimize the risk of oscillations. Even so, some types of transistors may require collec- The soft-start circuit protects the power transistors and tor-base capacitance for stability. Up to 1 amp of load rectifier diodes from high current surges during power current can be obtained with excellent regulation if the supply turn-on. When supply voltage is first applied to device selected maintains high current gain. the UC1526A, the under-voltage lockout circuit holds RESET LOW with Q3. Q1 is turned on, which holds the soft-start capacitor voltage at zero. The second collector of Q1 clamps the output of the error amplifier to ground, guaranteeing zero duty cycle at the driver outputs. When the supply voltage reaches normal operating range, RESET will go HIGH. Q1 turns off, allowing the internal 100m A current source to charge CS. Q2 clamps the error amplifier output to 1VBE above the voltage on CS. As the soft-start voltage ramps up to +5V, the duty cycle of the PWM linearly increases to whatever value Figure 1. Extending Reference Output Current the voltage regulation loop requires for an error null. Under-Voltage Lockout The under-voltage lockout circuit protects the UC1526A and the power devices it controls from inadequate sup- ply voltage, If +VIN is too low, the circuit disables the output drivers and holds the RESET pin LOW. This pre- vents spurious output pulses while the control circuitry is stabilizing, and holds the soft-start timing capacitor in a discharged state. The circuit consists of a +1.2V bandgap reference and comparator circuit which is active when the reference voltage has risen to 3VBE or +1.8V at 25°C. When the reference voltage rises to approximately +4.4V, the cir- Figure 3. Soft-Start Circuit Schematic cuit enables the output drivers and releases the RESET Digital Control Ports pin, allowing a normal soft-start. The comparator has The three digital control ports of the UC1526A are bi-di- 350mV of hysteresis to minimize oscillation at the trip rectional. Each pin can drive TTL and 5V CMOS logic di- point. When +VIN to the PWM is removed and the refer- rectly, up to a fan-out of 10 low-power Schottky gates. ence drops to +4.2V, the under-voltage circuit pulls RE- Each pin can also be directly driven by open-collector SET LOW again. The soft-start capacitor is immediately TTL, open-drain CMOS, and open-collector voltage discharged, and the PWM is ready for another soft-start comparators; fan-in is equivalent to 1 low-power Schot- cycle. tky gate. Each port is normally HIGH; the pin is pulled The UC1526A can operate from a +5V supply by con- LOW to activate the particular function. Driving SYNC necting the VREF pin to the +VIN pin and maintaining the LOW initiates a discharge cycle in the oscillator. Pulling supply between +4.8 and +5.2V. SHUTDOWN LOW immediately inhibits all PWM output pulses. Holding RESET LOW discharges the soft-start 5

UC1526A UC2526A UC3526A APPLICATIONS INFORMATION (cont.) capacitor. The logic threshold is +1.1V at +25(cid:176) C. Noise the SYNC pin will then lock the oscillator to the external immunity can be gained at the expense of fan-out with an frequency. external 2k pull-up resistor to +5V. Multiple devices can be synchronized together by pro- gramming one master unit for the desired frequency, and then sharing its sawtooth and clock waveforms with the slave units. All CT terminals are connected to the CT pin of the master and all SYNC terminals are likewise con- nected to the SYNC pin of the master. Slave RT termi- nals are left open or connected to VREF. Slave RD terminal may be either left open or grounded. Figure 4. Digital Control Port Schematic Oscillators The oscillator is programmed for frequency and dead time with three components: RT, CT and RD. Two wave- forms are generated: a sawtooth waveform at pin 10 for pulse width modulation, and a logic clock at pin 12. The following procedure is recommended for choosing timing values: Figure 6. Error Amplifier Connections 1. With RD= 0W (pin 11 shorted to ground) select values Error Amplifier for RT and CT from the graph on page 4 to give the de- The error amplifier is a transconductance design, with an sired oscillator period. Remember that the frequency at output impedance of 2MW . Since all voltage gain takes each driver output is half the oscillator frequency, and the place at the output pin, the open-loop gain/frequency frequency at the +VC terminal is the same as the oscilla- characteristics can be controlled with shunt reactance to tor frequency. ground. When compensated for unity-gain stability with 100pF, the amplifier has an open-loop pole at 800Hz. 2. If more dead time is required, select a larger value of RD. At 40kHz dead time increases by 400ns/W . The input connections to the error amplifier are deter- mined by the polarity of the switching supply output volt- 3. Increasing the dead time will cause the oscillator fre- age. For positive supplies, the common-mode voltage is quency to decrease slightly. Go back and decrease the +5.0V and the feedback connections in Figure 6A are value of RT slightly to bring the frequency back to the used. With negative supplies, the common-mode voltage nominal design value. is ground and the feedback divider is connected between The UC1526A can be synchronized to an external logic the negative output and the +5.0V reference voltage, as clock by programming the oscillator to free-run at a fre- shown in Figure 6B. quency 10% slower than the SYNC frequency. A periodic LOW logic pulse approximately 0.5m s wide at Figure 5. Oscillator Connections and Waveforms Figure 7. Push-Pull Configuration 6

UC1526A UC2526A UC3526A APPLICATIONS INFORMATION (cont.) Output Drivers +VC terminal to ground during switching; however, im- proved design has limited this cross-conduction period to The totem pole output drivers of the UC1526A are de- signed to source and sink 100mA continuously and less than 50ns. Capacitor decoupling at VC is recom- mended and careful grounding of Pin 15 is needed to in- 200mA peak. Loads can be driven either from the output sure that high peak sink currents from a capacitive load pins 13 and 16, or from the +VC, as required. do not cause ground transients. Since the bottom transistor of the totem-pole is allowed to saturate, there is a momentary conduction path from the Figure 8. Single-Ended Configuration Figure 9. Driving N-Channel Power MOSFETs TYPICAL CHARACTERISTICS OSCILLATOR PERIOD vs RT and CT OUTPUT BLANKING 7

UC1526A UC2526A UC3526A TYPICAL CHARACTERISTICS (Cont.) Output Driver Deadtime vs. RD Value Under Voltage Lockout Characteristic Error Amplifier Open Loop Gain vs. Frequency Current Limit Transfer Function Shutdown Delay Output Driver Saturation Voltage UNITRODE INTEGRATED CIRCUITS 7 CONTINENTAL BLVD. • MERRIMACK, NH 03054 TEL. (603) 424-2410 • FAX (603) 424-3460 8

PACKAGE OPTION ADDENDUM www.ti.com 6-Feb-2020 PACKAGING INFORMATION Orderable Device Status Package Type Package Pins Package Eco Plan Lead/Ball Finish MSL Peak Temp Op Temp (°C) Device Marking Samples (1) Drawing Qty (2) (6) (3) (4/5) 85515022A ACTIVE LCCC FK 20 1 TBD POST-PLATE N / A for Pkg Type -55 to 125 85515022A UC1526AL/ 883B 8551502VA ACTIVE CDIP J 18 1 TBD Call TI N / A for Pkg Type -55 to 125 8551502VA UC1526AJ/883B UC1526AJ ACTIVE CDIP J 18 1 TBD Call TI N / A for Pkg Type -55 to 125 UC1526AJ UC1526AJ883B ACTIVE CDIP J 18 1 TBD Call TI N / A for Pkg Type -55 to 125 8551502VA UC1526AJ/883B UC1526AL ACTIVE LCCC FK 20 1 TBD POST-PLATE N / A for Pkg Type -55 to 125 UC1526AL UC1526AL883B ACTIVE LCCC FK 20 1 TBD POST-PLATE N / A for Pkg Type -55 to 125 85515022A UC1526AL/ 883B UC2526ADW ACTIVE SOIC DW 18 40 Green (RoHS NIPDAU Level-2-260C-1 YEAR -25 to 85 UC2526ADW & no Sb/Br) UC2526ADWG4 ACTIVE SOIC DW 18 40 Green (RoHS NIPDAU Level-2-260C-1 YEAR -25 to 85 UC2526ADW & no Sb/Br) UC2526ADWTR ACTIVE SOIC DW 18 2000 Green (RoHS NIPDAU Level-2-260C-1 YEAR -25 to 85 UC2526ADW & no Sb/Br) UC2526AN ACTIVE PDIP N 18 20 Green (RoHS NIPDAU N / A for Pkg Type -25 to 85 UC2526AN & no Sb/Br) UC2526ANG4 ACTIVE PDIP N 18 20 Green (RoHS NIPDAU N / A for Pkg Type -25 to 85 UC2526AN & no Sb/Br) UC3526ADW ACTIVE SOIC DW 18 40 Green (RoHS NIPDAU Level-2-260C-1 YEAR 0 to 70 UC3526ADW & no Sb/Br) UC3526ADWG4 ACTIVE SOIC DW 18 40 Green (RoHS NIPDAU Level-2-260C-1 YEAR 0 to 70 UC3526ADW & no Sb/Br) UC3526ADWTR ACTIVE SOIC DW 18 2000 Green (RoHS NIPDAU Level-2-260C-1 YEAR 0 to 70 UC3526ADW & no Sb/Br) UC3526ADWTRG4 ACTIVE SOIC DW 18 2000 Green (RoHS NIPDAU Level-2-260C-1 YEAR 0 to 70 UC3526ADW & no Sb/Br) UC3526AN ACTIVE PDIP N 18 20 Green (RoHS NIPDAU N / A for Pkg Type 0 to 70 UC3526AN & no Sb/Br) UC3526J ACTIVE CDIP J 18 1 TBD Call TI N / A for Pkg Type 0 to 70 UC3526J Addendum-Page 1

PACKAGE OPTION ADDENDUM www.ti.com 6-Feb-2020 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. OTHER QUALIFIED VERSIONS OF UC1526A, UC2526A, UC3526A, UC3526M : •Catalog: UC3526A, UC3526AM, UC3526 •Military: UC2526AM, UC1526A, UC1526 NOTE: Qualified Version Definitions: Addendum-Page 2

PACKAGE OPTION ADDENDUM www.ti.com 6-Feb-2020 •Catalog - TI's standard catalog product •Military - QML certified for Military and Defense Applications Addendum-Page 3

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