Datasheet LTC3807 (Analog Devices) - 9

LTC3807
PIN FUNCTIONS (QFN/TSSOP) PLLIN/MODE (Pin 1/Pin 3):
External Synchronization
VFB (Pin 7/Pin 9):
Receives the remotely sensed feed- Input to Phase Detector and Forced Continuous Mode back voltage from an external resistive divider across Input. When an external clock is applied to this pin, the the output. phase-locked loop will force the rising TG signal to be
ITH (Pin 8/Pin 10):
Error Amplifier Outputs and Switching synchronized with the rising edge of the external clock, Regulator Compensation Point. The current comparator and the regulator operates in forced continuous mode. trip point increases with this control voltage. When not synchronizing to an external clock, this input determines how the LTC3807 operates at light loads. Pull-
PGOOD (Pin 9/Pin 11):
Open-Drain Logic Output. PGOOD ing this pin to ground selects Burst Mode operation. An is pulled to ground when the voltage on the VFB pin is not internal 100k resistor to ground also invokes Burst Mode within 10% of its set point. operation when the pin is floated. Tying this pin to INTVCC
TG (Pin 10/Pin 12):
High Current Gate Drives for Top forces continuous inductor current operation. Tying this N-channel MOSFET. This is the output of floating driver pin to a voltage greater than 1.2V and less than INTVCC with a voltage swing equal to INTV –1.3V selects pulse-skipping operation. CC superimposed on the switch node voltage SW.
SGND (Pins 2, 3, Exposed Pad Pin 21/Pins 4, 5, SW (Pin 11/ Pin 13):
Switch Node Connection to Induc-
Exposed Pad Pin 21):
Small-signal ground, must be routed tor. separately from high current grounds to the common (–) terminals of the C
BOOST (Pin 12/Pin 14):
Bootstrapped Supply to the Top- IN capacitor. Pins 2, 3/4, 5, must both be electrically connected to small signal ground for proper side Floating Driver. A capacitor is connected between the operation. The exposed pad must be soldered to PCB BOOST and SW pin and a Schottky diode is tied between ground for rated thermal performance. the BOOST and INTVCC pins. Voltage swing at the BOOST pin is from INTV
RUN (Pin 4/Pin 6):
Run Control Input. Forcing this pin CC to (VIN + INTVCC). below 1.16V shuts down the controller. Forcing this pin
BG (Pin 13/Pin 15):
High Current Gate Drive for Bottom below 0.7V shuts down the entire LTC3807, reducing (Synchronous) N-channel MOSFET. Voltage swing at this quiescent current to approximately 14µA. pin is from ground to INTVCC.
SENSE– (Pin 5/Pin 7):
The (–) Input to the Differential
INTVCC (Pin 14/Pin 16):
Output of the Internal Linear Current Comparator. When greater than INTV Low Dropout Regulator. The driver and control circuits CC – 0.5V, the SENSE– pin supplies power to the current comparator. are powered from this voltage source. Must be decoupled to PGND with a minimum of 2.2µF ceramic or other low
SENSE+ (Pin 6/Pin 8):
The (+) input to the differential ESR capacitor. Do not use the INTV current comparator is normally connected to DCR sensing CC pin for any other purpose. network or current sensing resistor. The ITH pin voltage and control ed offsets between the SENSE– and SENSE+ pins in conjunction with RSENSE set the current trip threshold. 3807fa For more information www.linear.com/LTC3807 9 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Package Description Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Package Description Revision History Related Parts