LTC3722-2 Linear Technology, LTC3722-2 Datasheet
LTC3722-2
Related parts for LTC3722-2
LTC3722-2 Summary of contents
Page 1
... The LTC3722-1 features peak current mode control with programmable slope compensation and lead- ing edge blanking, while the LTC3722-2 employs voltage mode control with voltage feedforward capability. The LTC3722-1/LTC3722-2 feature extremely low operat- ing and start-up currents ...
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... LTC3722-1/LTC3722 ABSOLUTE AXI U RATI GS (Note GND (Low Impedance Source) ......... –0.3 to 10V CC (Chip Self Regulates at 10.3V) UVLO to GND ................................................ –0 All Other Pins to GND (Low Impedance Source) ....................... –0.3 to 5.5V V (Current Fed) ................................................. 25mA CC U PACKAGE/ORDER I FOR ATIO TOP VIEW SYNC 1 24 ...
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... Initial Accuracy OSCT Total Variation OSCV C Ramp Amplitude T OSYT SYNC Threshold OSYW Minimum SYNC Pulse Width OSYR SYNC Frequency Range LTC3722-1/LTC3722-2 The denotes the specifications which apply over the full operating = 9.5V 270pF DPRG CONDITIONS Measured ...
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... LTC3722-1/LTC3722-2 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T SYMBOL PARAMETER Error Amplifier V FB Input Voltage FB FBI FB Input Range A Open-Loop Gain VOL IIB Input Bias Current V Output High OH V Output Low OL I Output Source Current SOURCE I Output Sink Current SINK ...
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... I (mA) SHUNT 5.05 5.00 4.95 4.90 4.85 4. 100 (k ) 3722 • G04 100 –180 –270 –360 40 60 100 80 3722 • G06 LTC3722-1/LTC3722-2 www.DataSheet4U.com Oscillator Frequency vs Temperature 260 C = 270pF T 250 240 230 220 50 – 60 – 40 – TEMPERATURE ( C) 3722 • G02 REF REF ...
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... REF outputs The delay is approximately equal to (1.66e- The nominal voltage on DPRG is 2V. DPRG RAMP (NA/Pin 2): Input to Phase Modulator Comparator for LTC3722-2 only. The voltage on RAMP is internally level shifted by 650mV. 6 Delay Hysteresis Current vs Temperature 1.278 SBUS = 1.5V 1 ...
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... SS (Pin 7/Pin 7): Soft-Start/Restart Delay Circuitry Timing Capacitor. A capacitor from SS to GND provides a con- trolled ramp of the current command (LTC3722-1), or duty cycle (LTC3722-2). During overload conditions SS is discharged to ground initiating a soft-start cycle. NC (Pin 8/Pin 8): No Connection. Tie this pin to GND. PDLY (Pin 9/Pin 9): Passive Leg Delay Circuit Input. PDLY is connected through a voltage divider to the left leg of the bridge in adaptive ZVS mode ...
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... LTC3722-1/LTC3722-2 W BLOCK DIAGRA S V UVLO UVLO CC REF AND LDO 10.25V = OFF REF GOOD SYSTEM FB UVLO – – + 1.2V 5V ERROR AMPLIFIER R1 COMP 50k – 650mV 14.9k – REF SHUTDOWN CURRENT LIMIT + – 650mV M2 COMPENSATION BLANK ...
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... RAMP 650mV V REF SHUTDOWN CURRENT LIMIT + – 650mV BLANK – 270mV PULSE BY PULSE CURRENT LIMIT LTC3722-2 Voltage Mode SYNC Phase Shift PWM V C SYNC REF OSC 1.2V REF GOOD ENABLE DISABLE GOOD PHASE MODULATOR ...
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... LTC3722-1/LTC3722-2 phase shift PWM controllers pro- vide enhanced performance and simplify the design task required for a ZVS phase shifted full-bridge converter. The primary attributes of the LTC3722-1/LTC3722-2 as com- pared to currently available solutions include: 1) Truly adaptive and accurate (DirectSense technology) ZVS with programmable timeout. ...
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... Programmable system undervoltage lockout and hys- teresis. Benefit: provides an accurate turn-on voltage for power supply and reduces external circuitry result, the LTC3722-1/LTC3722-2 makes the ZVS topology feasible for a wider variety of applications, in- cluding those at lower power levels. The LTC3722-1/LTC3722-2 control four external power switches in a full-bridge arrangement ...
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... LTC3722-1/LTC3722-2 U OPERATIO on the active leg from the ground reference point to V always occur, independent of load current as long as energy in the transformer’s magnetizing and leakage in- ductance is greater than the capacitive energy. That is, 2 1/2 • • I > 1/2 • 2 • C • ...
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... POWER PULSE L01 MC N:1 L02 + • T )/L L01 IN OVL MAG FREEWHEEL INTERVAL Figure 1. ZVS Operation LTC3722-1/LTC3722-2 www.DataSheet4U.com V OUT LOAD PRIMARY AND SECONDARY SHORTED OUT LOAD 3722 F01 V OUT LOAD 372212i 13 ...
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... To set up the ADLY and PDLY resistors, first determine at what drain to source voltage to turn-on the MOSFETs. Finite delays exist between the time at which the LTC3722- 1/LTC3722-2 controller output transitions, to the time at which the power MOSFET switches on due to MOSFET turn on delay and external driver circuit delay. Ideally, we want the power MOSFET to switch at the instant there is zero volts across it ...
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... V voltage is sufficient to begin switching operation (under voltage lockout). With its typical 10.2V turn-on voltage and 4.2V UVLO hysteresis, the LTC3722-1/LTC3722-2 is tolerant of loosely regulated input sources such as an auxiliary transformer winding. The V sinking up to 25mA of externally applied current. The ...
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... UVLO V IN 3722 F0A Programming the LTC3722-1/LTC3722-2 Oscillator The high accuracy LTC3722-1/LTC3722-2 oscillator cir- cuit provides flexibility to program the switching fre- quency, slope compensation, and synchronization with minimal external components. The LTC3722-1/LTC3722-2 www.DataSheet4U.com filter capacitor is needed, since CC V ...
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... The C charge current is internally set to a high value (>10mA). The dedicated SYNC I/O pin easily achieves synchroniza- tion. The LTC3722-1/LTC3722-2 can be set up to either synchronize other PWM chips or be synchronized by another chip or external clock source. The 1.8V SYNC ...
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... The LTC3722-1/LTC3722-2 are compatible with either resis- tive sensing or current transformer methods. Internally connected to the LTC3722-1/LTC3722-2 CS pin are two comparators that provide pulse-by-pulse and overcurrent shutdown functions respectively. (See Figure 10) The pulse-by-pulse comparator has a 270mV nominal threshold ...
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... P Current Transformer Sensing A current sense transformer can be used in lieu of resistive sensing with the LTC3722-1/LTC3722-2. Current sense transformers are available in many styles from several manufacturers. A typical sense transformer for this appli- cation will use a 1:50 turns ratio (N), so that the sense resistor value is N times larger, and the secondary current N times smaller than in the resistive sense case ...
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... LTC3722-1/LTC3722-2 U OPERATIO 4. Using two CS transformers summed together. 5. Choose a CS transformer optimized for high frequency applications. MB SOURCE R SLOPE RAMP OPTIONAL FILTERING Figure 11. Current Transformer Sense Circuitry Phase Modulator (LTC3722-1) The LTC3722-1 phase modulation control circuitry is comprised of the phase modulation comparator and logic, the error amplifier, and the soft-start amplifier (see Fig- ure 12) ...
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... The dual output inductors deliver current to the output capacitor 180 degrees out of phase, in effect, partially canceling each other’s ripple current. This reduction is LTC3722-1/LTC3722-2 maximized at high duty cycle and decreases as the duty cycle reduces. This means that a current doubler con- verter requires less output capacitance for the same performance as a conventional converter ...
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... LT1431 or equivalent. In nonisolated systems, the compensation network is lo- cated around the LTC3722-1/LTC3722-2’s error amplifier. In current mode control, the dominant system pole is determined by the load resistance (V capacitor 1/(2 • R • ...
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... REF COLL R – 2.5V ESR R D LT1431 OR EQUIVALENT PRECISION ERROR AMP AND REFERENCE Figure 13. Compensation for Polymer Electrolytic LTC3722-1/LTC3722-2 www.DataSheet4U.com sets the low frequency should be set such so that F I /8). Use a bode plot to graphi used to attenuate f and R C ...
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... These characteristics improve transient response, particularly overshoot, and improve ZVS ability at light loads. Programming the Synchronous Rectifier Turn-Off Delay The LTC3722-1/LTC3722-2 controllers include a feature to program the turn-off edge of the secondary side syn- chronous rectifier MOSFETs relative to the beginning SPRG 24 new primary side power delivery pulse ...
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... Synchronous rectification of the current doubler second- ary requires two ground referenced N-channel MOSFETs. The timing of the LTC3722-1/LTC3722-2 drive signals is shown in the Timing Diagram. 1 NOTE: INDUCTOR(S) DUTY CYCLE IS LIMITED TO 50% WITH CURRENT DOUBLER PHASE SHIFT CONTROL ...
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... VDS, eliminating the “Miller” effect. Low turn-off resis- tance is critical, however, in order to prevent excessive turn-off losses resulting from the same Miller effects that were not an issue for turn on. The LTC3722-1/LTC3722-2 LTC3722 OUTE OUTF ...
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... TYP .015 .004 45 .053 – .068 (0.38 0.10) (1.351 – 1.727) 0 – 8 TYP .008 – .012 (0.203 – 0.305) LTC3722-1/LTC3722-2 www.DataSheet4U.com .337 – .344* (8.560 – 8.738) .033 (0.838 ...
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... LTC3722-1/LTC3722-2 U TYPICAL APPLICATIO 1 10V IN 0. 0.82 F 36V TO 100V 100V 72V D3 – 0.01 F 785 10V Q10 0.04 1.5W A_LEG V P_LEG IN 15.4k 13.3k 13.3k 1.5pF 1.5pF 100V 100V 13.3k 13.3k 15k 15.4k 1k SBUS 1k ADLY PDLY 15k 1k 10V ADLY A C PDLY SBUS ...