UC1714/5 UC2714/5 UC3714/5 Complementary Switch FET Drivers FEATURES DESCRIPTION • Single Input (PWM and TTL Compatible) • Time Delays Between Power and Auxiliary Outputs Independently Programmable from 50ns to 500ns These two families of high speed drivers are designed to provide drive waveforms for complementary switches. Complementary switch configurations are commonly used in synchronous rectification circuits and active clamp/reset circuits, which can provide zero voltage switching. In order to facilitate the soft switching transitions, independently programmable delays between the two output waveforms are provided on these drivers. The delay pins also have true zero voltage sensing capability which allows immediate activation of the corresponding switch when zero voltage is applied. These devices require a PWM-type input to operate and can be interfaced with commonly available PWM controllers. • Time Delay or True Zero-Voltage Operation Independently Configurable for Each Output In the UC1714 series, the AUX output is inverted to allow driving a p-channel MOSFET. In the UC1715 series, the two outputs are configured in a true complementary fashion. • High Current Power FET Driver, 1.0A Source/2A Sink • Auxiliary Output FET Driver, 0.5A Source/1A Sink • Switching Frequency to 1MHz • Typical 50ns Propagation Delays • ENBL Pin Activates 220µA Sleep Mode • Power Output is Active Low in Sleep Mode • Synchronous Rectifier Driver BLOCK DIAGRAM 2 PWR 50ns –500ns 4 AUX TIMER S Q 1 VCC 3 GND 50ns –500ns INPUT 6 TIMER S Q T1 7 R T2 UC1714 ONLY VREF 5 R VREF VCC 5V BIAS ENBL 3V GND LOGIC GATES TIMER REF 1.4V ENBL 8 ENABLE Note: Pin numbers refer to J, N and D packages. 02/99 UDG-99028 UC1714/5 UC2714/5 UC3714/5 ABSOLUTE MAXIMUM RATINGS Input Voltage Range (INPUT, ENBL) . . . . . . . . . . −0.3V to 20V Storage Temperature Range . . . . . . . . . . . . . . −65°C to 150°C Operating Junction Temperature (Note 1) . . . . . . . . . . . . 150°C Lead Temperature (Soldering 10 seconds) . . . . . . . . . . . 300°C Supply Voltage VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20V Power Driver IOH continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −200mA peak. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −1A Power Driver IOL continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 400mA peak. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2A Auxiliary Driver IOH continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −100mA peak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −500mA Auxiliary Driver IOL continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200mA peak. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A Note 1: Unless otherwise indicated, voltages are referenced to ground and currents are positive into, negative out of, the specified terminals. Note 2: Consult Packaging Section of databook for thermal limitations and specifications of packages. CONNECTION DIAGRAMS DIL-8, SOIC-8 (Top View) J or N, D Packages SOIC-16 (Top View) DP Package ELECTRICAL CHARACTERISTICS: Unless otherwise stated, VCC = 15V, ENBL ≥ 2V, RT1 = 100kΩ from T1 to GND, RT2 = 100kΩ from T2 to GND, and −55°C < TA < 125°C for the UC1714/5, −40°C < TA < 85°C for the UC2714/5, and 0°C < TA < 70°C for the UC3714/5, TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Overall 20 V ICC, nominal ENBL = 2.0V 7 18 24 mA ICC, sleep mode ENBL = 0.8V 200 300 µA VCC Power Driver (PWR) Pre Turn-on PWR Output, Low VCC = 0V, IOUT = 10mA, ENBL 0.8V 0.3 1.6 V PWR Output Low, Sat. (VPWR) INPUT = 0.8V, IOUT = 40mA 0.3 0.8 V INPUT = 0.8V, IOUT = 400mA 2.1 2.8 V PWR Output High, Sat. (VCC − VPWR) INPUT = 2.0V, IOUT = −20mA 2.1 3 V INPUT = 2.0V, IOUT = −200mA 2.3 3 V Rise Time CL = 2200pF 30 60 ns Fall Time CL = 2200pF 25 60 ns T1 Delay, AUX to PWR INPUT rising edge, RT1 = 10kΩ (Note 4) 20 35 80 ns T1 Delay, AUX to PWR INPUT rising edge, RT1 = 100kΩ (Note 4) 350 500 700 ns PWR Prop Delay INPUT falling edge, 50% (Note 3) 35 100 ns 2 UC1714/5 UC2714/5 UC3714/5 ELECTRICAL CHARACTERISTICS: Unless otherwise stated, VCC = 15V, ENBL ≥ 2V, RT1 = 100kΩ from T1 to GND, RT2 = 100kΩ from T2 to GND, and −55°C < TA < 125°C for the UC1714/5, −40°C < TA < 85°C for the UC2714/5, and 0°C < TA < 70°C for the UC3714/5, TA = TJ. PARAMETER TEST CONDITIONS MIN TYP MAX UNITS Auxiliary Driver (AUX) AUX Output Low, Sat (VAUX) AUX Output High, Sat (VCC – VAUX) VIN = 2.0V, IOUT = 20mA 0.3 0.8 V VIN = 2.0V, IOUT = 200mA 1.8 2.6 V VIN = 0.8V, IOUT = -10mA 2.1 3.0 V VIN = 0.8V, IOUT = -100mA 2.3 3.0 V Rise Time CL = 1000pF 45 60 ns Fall Time CL = 1000pF 30 60 ns T2 Delay, PWR to AUX INPUT falling edge, RT2 = 10kΩ (Note 4) 20 50 80 ns T2 Delay, PWR to AUX INPUT falling edge, RT2 = 100kΩ (Note 4) 250 350 550 ns AUX Prop Delay INPUT rising edge, 50% (Note 3) 35 80 ns Enable (ENBL) Input Threshold 1.2 2.0 V Input Current, IIH ENBL = 15V 0.8 1 10 µA Input Current, IIL ENBL = 0V −1 −10 µA −1.6 −2 mA 3 3.3 V 40 70 ns −1.2 −2 mA 3 3.3 V 50 100 ns T1 Current Limit T1 = 0V Nominal Voltage at T1 Minimum T1 Delay 2.7 T1 = 2.5V, (Note 4) T2 Current Limit T2 = 0V Nominal Voltage at T2 Minumum T2 Delay 2.7 T2 = 2.5V, (Note 4) Input (INPUT) Input Threshold 1.4 2.0 V Input Current, IIH INPUT = 15V 0.8 1 10 µA Input Current, IIL INPUT = 0V −5 −20 µA Note 3: Propagation delay times are measured from the 50% point of the input signal to the 10% point of the output signal’s transition with no load on outputs. Note 4: T1 delay is defined from the 50% point of the transition edge of AUX to the 10% of the rising edge of PWR. T2 delay is defined from the 90% of the falling edge of PWR to the 50% point of the transition edge of AUX. PIN DESCRIPTIONS AUX: The AUX switches immediately at INPUT’s rising edge but waits through the T2 delay after INPUT’s falling edge before switching. AUX is capable of sourcing 0.5A and sinking 1.0A of drive current. See the Time Relationships diagram below for the difference between the UC1714 and UC1715 for INPUT, MAIN, and AUX. During sleep mode, AUX is inactive with a high impedance. The ENBL input will place the device into sleep mode when it is a logical low. The current into VCC during the sleep mode is typically 220µA. GND: This is the reference pin for all input voltages and the return point for all device currents. It carries the full peak sinking current from the outputs. Any tendency for the outputs to ring below GND voltage must be damped or clamped such that GND remains the most negative potential. ENBL: The ENBL input switches at TTL logic levels (approximately 1.2V), and its input range is from 0V to 20V. 3 UC1714/5 UC2714/5 UC3714/5 PIN DESCRIPTIONS (cont.) INPUT: The input switches at TTL logic levels (approximately 1.4V) but the allowable range is from 0V to 20V, allowing direct connection to most common IC PWM controller outputs. The rising edge immediately switches the AUX output, and initiates a timing delay, T1, before switching on the PWR output. Similarly, the INPUT falling edge immediately turns off the PWR output and initiates a timing delay, T2, before switching the AUX output. T2: This pin functions in the same way as T1 but controls the time delay between PWR turn-off and activation of the AUX switch. T1, T2: The resistor on each of these pins sets the charging current on internal timing capacitors to provide independent time control. The nominal voltage level at each pin is 3V and the current is internally limited to 1mA. The total delay from INPUT to each output includes a propagation delay in addition to the programmable timer but since the propagation delays are approximately equal, the relative time delay between the two outputs can be assumed to be solely a function of the programmed delays. The relationship of the time delay vs. RT is shown in the Typical Characteristics curves. It should be noted that if the input signal comes from a controller with FET drive capability, this signal provides another option. INPUT and PWR provide a delay only at the leading edge while INPUT and AUX provide the delay at the trailing edge. PWR: The PWR output waits for the T1 delay after the INPUT’s rising edge before switching on, but switches off immediately at INPUT’s falling edge (neglecting propagation delays). This output is capable of sourcing 1A and sinking 2A of peak gate drive current. PWR output includes a passive, self-biased circuit which holds this pin active low, when ENBL ≥ 0.8V regardless of VCC’s voltage. Either or both pins can alternatively be used for voltage sensing in lieu of delay programming. This is done by pulling the timer pins below their nominal voltage level which immediately activates the timer output. VCC: The VCC input range is from 7V to 20V. This pin should be bypassed with a capacitor to GND consistent with peak load current demands. T1: A resistor to ground programs the time delay between AUX switch turn-off and PWR turn-on. TYPICAL CHARACTERISTICS INPUT PROPAGATION DELAYS PWR OUTPUT T1 vs RT1 T2 vs RT2 500 400 T2 DELAY DELAY (ns) T1 DELAY UC1714 AUX OUTPUT 300 200 100 0 UC1715 AUX OUTPUT 0 10 20 30 40 UDG-99027 Time relationships. (Notes 3, 4) T1 Delay, T2 Delay vs. RT 4 50 60 RT (kW) 70 80 90 100 UC1714/5 UC2714/5 UC3714/5 TYPICAL CHARACTERISTICS (cont.) 21 18 17 19 Icc (mA) Icc (mA) 20 18 16 17 16 15 0 100 200 300 400 500 600 700 800 900 1000 0 10 20 30 40 ICC vs Switching Frequency with No Load and 50% Duty Cycle RT1 = RT2 = 50k 70 80 90 100 75 100 600 RT1 = 100k 500 Deadband Delay (ns) 500 Deadband Delay (ns) 60 ICC vs RT with Opposite RT = 50k 600 400 300 RT1 = 50k 200 100 0 -75 50 RT (kΩ) Switching Frequency (kHz) 400 RT2 = 100k 300 RT2 = 50k 200 100 RT1 = 10k RT1 < 6k -50 -25 0 25 50 Temperature (°C) 75 100 0 -75 125 RT2 = 10k RT2 < 6k -50 -25 0 25 50 125 Temperature (°C) T1 Deadband vs. Temperature AUX to PWR T2 Deadband vs. Temperature PWR to AUX TYPICAL APPLICATIONS UDG-94011 Figure 1. Typical application with timed delays. UDG-94012 Figure 2. Using the timer input for zero-voltage sensing. 5 UC1714/5 UC2714/5 UC3714/5 TYPICAL APPLICATIONS (cont.) UDG-94013 Figure 3. Self-actuated sleep mode with the absence of an input PWM signal. Wake up occurs with the first pulse while turn-off is determined by the (RTO CTO) time constant. UDG-94015-2 Figure 4. Using the UC1715 as a complementary synchronous rectifier switch driver with n-channel FETs UDG-94014-1 Figure 5. Synchronous rectifier application with a charge pump to drive the high-side n-channel buck switch. VIN is limited to 10V as VCC will rise to approximately 2VIN. 6 UC1714/5 UC2714/5 UC3714/5 TYPICAL APPLICATIONS (cont.) UDG-94016-1 Figure 6. Typical forward converter topology with active reset provided by the UC1714 driving an N-channel switch (Q1) and a P-channel auxilliary switch (Q2). UDG-94017-1 Figure 7. Using an N-channel active reset switch with a floating drive command. 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