Datasheet LTC3707 (Analog Devices) - 8

LTC3707
PIN FUNCTIONS RUN/SS1, RUN/SS2 (Pins 1, 15):
Combination of soft-start,
3.3VOUT (Pin 10):
Output of a linear regulator capable run control inputs and short-circuit detection timers. A of supplying 10mA DC with peak currents as high as capacitor to ground at each of these pins sets the ramp 50mA. time to full output current. Forcing either of these pins
PGND (Pin 20):
Driver Power Ground. Connects to the back below 1.0V causes the IC to shut down the circuitry sources of bottom (synchronous) N-channel MOSFETs, required for that particular controller. Latchoff overcurrent anodes of the Schottky rectifi ers and the (–) terminal(s) protection is also invoked via this pin as described in the of C Applications Information section. IN.
INTV SENSE1+, SENSE2+ (Pins 2, 14):
The (+) Input to the
CC (Pin 21):
Output of the Internal 5V Linear Low Dropout Regulator and the EXTV Differential Current Comparators. The I CC Switch. The driver and TH pin voltage and control circuits are powered from this voltage source. Must controlled offsets between the SENSE– and SENSE+ pins in be decoupled to power ground with a minimum of 4.7μF conjunction with RSENSE set the current trip threshold. tantalum or other low ESR capacitor. The INTVCC regulator
SENSE1–, SENSE2– (Pins 3, 13):
The (–) Input to the standby function is determined by the STBYMD pin. Differential Current Comparators.
EXTVCC (Pin 22):
External Power Input to an Internal Switch
VOSENSE1, VOSENSE2 (Pins 4, 12):
Receives the remotely- Connected to INTVCC. This switch closes and supplies VCC sensed feedback voltage for each controller from an external power, bypassing the internal low dropout regulator, when- resistive divider across the output. ever EXTVCC is higher than 4.7V. See EXTVCC connection in Applications section. Do not exceed 7V on this pin.
FREQSET (Pin 5):
Frequency Control Input to the Oscillator. This pin can be left open, tied to ground, tied to INTVCC
BG1, BG2 (Pins 23, 19):
High Current Gate Drives for Bot- or driven by an external voltage source. This pin can also tom (Synchronous) N-Channel MOSFETs. Voltage swing be used with an external phase detector to build a true at these pins is from ground to INTVCC. phase-locked loop.
VIN (Pin 24):
Main Supply Pin. A bypass capacitor should
STBYMD (Pin 6):
Control pin that determines which cir- be tied between this pin and the signal ground pin. cuitry remains active when the controllers are shut down
BOOST1, BOOST2 (Pins 25, 18):
Bootstrapped Supplies and/or provides a common control point to shut down both to the Top Side Floating Drivers. Capacitors are connected controllers. See the Operation section for details. between the boost and switch pins and Schottky diodes are
FCB (Pin 7):
Forced Continuous Control Input. This input tied between the boost and INTVCC pins. Voltage swing at acts on both controllers and is normally used to regulate a the boost pins is from INTVCC to (VIN + INTVCC). secondary winding. Pulling this pin below 0.8V will force
SW1, SW2 (Pins 26, 17):
Switch Node Connections to continuous synchronous operation on both controllers. Inductors. Voltage swing at these pins is from a Schottky Do not leave this pin fl oating. diode (external) voltage drop below ground to VIN.
ITH1, ITH2 (Pins 8, 11):
Error Amplifi er Output and Switching
TG1, TG2 (Pins 27, 16):
High Current Gate Drives for Regulator Compensation Point. Each associated channels’ Top N-Channel MOSFETs. These are the outputs of fl oat- current comparator trip point increases with this control ing drivers with a voltage swing equal to INTV voltage. CC – 0.5V superimposed on the switch node voltage SW.
SGND (Pin 9):
Small Signal Ground common to both
PGOOD (Pin 28):
Open-Drain Logic Output. PGOOD is controllers, must be routed separately from high current pulled to ground when the voltage on either V grounds to the common (–) terminals of the C OSENSE pin OUT is not within ±7.5% of its set point. capacitors. 3707fb 8