LTP8800-4A

8

Rev. A

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PIN FUNCTIONS

SMBALERT (Pin 1): Power-Good Output (Push-Pull). This

pin is also used as the PMBus ALERT signal. If not used,

this pin should be left floating.

ISHARE (Pin 2): Analog Current Sharing Input and Output.

This pin must connect to other μModule IC’s ISHARE pins

for current sharing. If not used, pin should be left floating.

CTRL (Pin 3): Power Supply ON Input. This pin performs

hardware On/Off control. If this pin is not used, connect

to 3V3.

ADD (Pin 4): I2C/PMBus Address Select Input. Connect

a resistor from ADD to GND. See the applications section

for more information about the PMBus address selection.

VS+ (Pin 5): Non-Inverting Voltage Sense Input. This pin

functions as the Kelvin sense of VOUT at the load as well as

the feedback point for the converter control loop. The VS+

pin can be directly tied to the load through a resistor or

to a precision feedback resistor divider connected to the

output voltage. The VS+ pin requires 100pF capacitance to

the VS– pin placed close to the LTP8800-4A. The VS+ feed-

back resistors need to have a parallel resistance of <2k.

VS– (Pin 6): Inverting Voltage Sense Input. This pin func-

tions as the Kelvin sense of GND at the load as well as the

GND connection for the feedback point for the converter

control loop.

SYNC (Pin 7): Synchronization input signal. This pin is

used as a reference for the internal PWM frequency and is

referenced to GND. Apply a 50% nominal duty-cycle clock

input. If this pin is not used, connect to GND and program

Register 0xFE55 [6] = 1. The μModule is designed and

programmed to operate at 549kHz from the factory. If

using external SYNC do not deviate ±10% from 549kHz.

3V3 (Pin 8): The 3V3 pin powers internal μModule cir-

cuitry including the ADP1055 digital controller. Typical

3V3 supply current when operating is 60mA. This pin

must be powered before the μModule can begin deliver-

ing power.

GND (Pins 9, 14, 15, 19): μModule Ground. The GND pins

carry high current and must be connected to large planes

with sufficient internal layers. Be sure to keep the voltage

at the pins roughly equal by taking care of the direction of

current flow and debiasing of the ground planes.

7V0 (Pin 10): The 7V0 pin powers internal μModule cir-

cuitry including gate drivers. The typical 7V0 supply cur-

rent when operating is 0.22A. This pin must be powered

before the μModule can begin delivering power.

VOUT (Pins 11,12,13,16,17,18): The VOUT pins carry the

high output current of the converter. As such, the pins

must be connected to large power planes with sufficient

internal layers. The PCB layout must be such that the

two sets of VOUT pins see roughly the same voltage. This

ensures high efficiency and balanced currents. Output

voltage is digitally programmable from 0.5V to 1.1V. VOUT

pins are two rows of terminals and carry high steady-state

output currents (from 0A up to 200A) and transient cur-

rents up to 250A.

SCL (Pin 20): I2C/PMBus Serial Clock Input and Output

(Open-Drain).

SDA (Pin 21): I2C/PMBus Serial Data Input and Output

(Open-Drain).

VIN (Pin 22): The VIN pin supplies current to the primary

power switches and operates from 54V/48V nominal

inputs; for further details, see Absolute Maximum Ratings

and Electrical Characteristics table for input voltage range.

The LTP8800-4A requires 4µF of low ESR ceramic bypass

capacitor; be sure to place the bypass caps as close to the

μModule VIN and GND as possible.