LT8602 datasheet(13/38 Pages) LINER

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LT8603

8603f

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corresponding feedback pin to the lesser of 1V or the

voltage on the associated TRKSS pin.

FB3 (Pin 27): Feedback Input Pin for the Low Voltage

Converter. The converter regulates FB3 to 0.8V.

INTVCC (Pin 28): Internal Regulator Bypass. Do not load

the INTVCC pin with external circuitry. INTVCC is 3.1V

when BIAS < 3.1V, 3.4V when BIAS > 3.4V, and equal to

BIAS when BIAS is between 3.1V and 3.4V. Decouple to

ground with a low ESR 4.7µF capacitor.

RT (Pin 29): Frequency Programming Resistor. Connect

a resistor between this pin and ground to set the internal

oscillator frequency. This pin should not be left open.

RUN3 (Pin 30): Enable Input For Low Voltage Channel 3.

Channel 3 is enabled when the voltage on this pin exceeds

1.2V. The RUN3 pin has a precise threshold so it can be

used to create a UVLO function or be sequenced from

another channel. There is an internal soft-start timer

which ramps the output up in approximately 1ms.

CPOR (Pin 31): Power-On Reset Timing Capacitor.

A capacitor from this pin to ground sets the period of

the power-on reset oscillator timer. See the Applications

Information Section for details.

RST (Pin 32): Active Low Reset Output. This pin is the

output of the power-on reset function. This pin is an open-

drain output with a weak pull-up to approximately 2V. This

pin is held low until the power on reset timer times out.

SYNC (Pin 33): Clock Synchronization and Mode Select

Input. This pin allows the LT8603 to synchronize its

switching frequency to an external clock. When an external

clock is applied, the LT8603 will operate in pulse-skipping

mode. If clock synchronization is not used, connect this

pin to ground to enable low ripple Burst Mode operation

or connect high to enable pulse-skipping operation.

PVIN3 (Pin 34): Input Supply Voltage to Low Voltage

Channel 3. This pin will normally be connected to the

output of one of the high voltage converters but can be

supplied from any voltage in the specified range. It should

be bypassed locally with a low ESR ceramic capaci-

tor to ground with a low inductance connection to the

exposed pad.

SW3 (Pin 36): Low Voltage Converter Switch Node. This

is the output of the internal power switches for Channel 3.

PVIN1, PVIN2 (Pins 37, 14): Input Supply to High Voltage

Channels 1 and 2, respectively. These pins can be pow-

ered from the boost converter output or any voltage in

the specified range. Each pin should be bypassed locally

with a low ESR ceramic capacitor to ground with a low

inductance connection to the exposed pad.

POREN (Pin 39): Power-On Reset Enable. This is a logic

input that starts the ramp on the POR timing capacitor.

This input has a weak pull-up to allow direct connection

to open-drain outputs.

PIN FUNCTIONS

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