LT8610AC datasheet(8/31 Pages) AD

8 / 31 page

Data Sheet

LT8615

analog.com

Rev 0

8 of 31

10 to 11,

Exposed

Pad Pin

GND

Ground. Place the negative terminal of the input capacitor as close to the GND pins as

possible. The exposed pad should be soldered to the PCB for good thermal

performance.

TR/SS

Output Tracking and Soft-Start Pin. This pin allows user control of output voltage

ramp rate during start-up. A TR/SS voltage below 0.787V forces the LT8615 to regulate

the FB pin to equal the TR/SS pin voltage. When TR/SS is above 0.787V, the tracking

function is disabled and the internal reference resumes control of the error amplifier.

An internal 2μA pull-up current from INTVCC on this pin allows a capacitor to program

output voltage slew rate. This pin is pulled to ground with a 300Ω MOSFET during

shutdown and fault conditions; use a series resistor if driving from a low impedance

output.

The PG pin is the open-drain output of an internal comparator. PG remains low until

the FB pin is within ±8% of the final regulation voltage, and there are no fault

conditions. PG is valid when VIN is above 3V, regardless of EN/UV pin state.

The LT8615 regulates the FB pin to 0.787V. Connect the feedback resistor divider tap to

this pin. Also, connect a phase lead capacitor between FB and VOUT. Typically, this

capacitor is 4.7pF to 22pF.

SYNC

External Clock Synchronization Input. Ground this pin for low ripple Burst Mode

operation at low output loads. Tie to a clock source for synchronization to an external

frequency. Leave floating for pulse-skipping mode with no spread-spectrum

modulation. Tie to INTVCC or tie to a voltage between 3.2V and 5.0V for pulse-skipping

mode with spread-spectrum modulation. When in pulse-skipping mode, the IQ

increases to several mA.

A resistor is tied between RT and ground to set the switching frequency.

LT8610AC Datasheet(PDF) 8 Page - Analog Devices