LT8393EUFDM datasheet(12/32 Pages) AD

12 / 32 page

LT8393

Rev. A

For more information www.analog.com

PIN FUNCTIONS

PWM: PWM Dimming Input. The PWM pin can be used

in two ways: external PWM dimming and internal PWM

dimming. For external PWM dimming, drive this pin with

a digital pulse from 0V to a voltage higher than 1.5V to

control PWM dimming of the LED string. Make sure the

RP pin is tied to ground in this case. For internal PWM

dimming, apply an analog voltage between 1V and 2V to

generate an internal digital pulse by comparing with the

internal ramp. If PWM dimming is not used, tie this pin to

INTVCC. Forcing the pin low turns off TG1 and TG2, turns

on BG1 and BG2, disconnects the VC pin from all internal

loads, and turns off PWMTG.

PWMTG: PWM Dimming Top Gate Drive. A buffered and

inverted version of the PWM input signal, the PWMTG

pin drives an external high side PMOS PWM switch with

a voltage swing from the higher voltage of (VOUT –10V)

and 1V to VOUT. Leave this pin unconnected if not used.

VOUT: Output Supply. The VOUT pin must be tied to the

power output to determine the buck, buck-boost, or boost

operation regions. The VOUTpinalsoservesaspositiverail

for the PWMTG drive. Locally bypass this pin to ground

with a minimum 1µF ceramic capacitor.

BST2: Boost Side Bootstrap Floating Driver Supply. The

BST2 pin requires an external bootstrap Schottky diode

from the INTVCC pin and requires an external bootstrap

capacitor to the SW2 pin.

TG2: Boost Side Top Gate Drive. Drives the gate of boost

side top N-Channel MOSFET with a voltage swing from

SW2 to BST2.

SW2: Boost Side Switch Node.

BG2: Boost Side Bottom Gate Drive. Drives the gate of

boost side bottom N-Channel MOSFET with a voltage

swing from ground to INTVCC.

INTVCC: Internal 5V Linear Regulator Output. The INTVCC

linear regulator is supplied from the VIN pin, and powers

the internal control circuitry and gate drivers. Locally

bypass this pin to ground with a minimum 4.7µF ceramic

capacitor.

BG1: Buck Side Bottom Gate Drive. Drives the gate of buck

side bottom N-channel MOSFET with a voltage swing from

ground to INTVCC.

SW1: Buck Side Switch Node.

TG1: Buck Side Top Gate Drive. Drives the gate of buck

side top N-channel MOSFET with a voltage swing from

SW1 to BST1.

BST1: Buck Side Bootstrap Floating Driver Supply. The

BST1 pin has an integrated bootstrap Schottky diode

from the INTVCC pin and requires an external bootstrap

capacitor to the SW1 pin.

LSN: Negative Terminal of the Buck Side Inductor Current

Sense Resistor (RSENSE). Ensure accurate current sense

with Kelvin connection.

LSP: Positive Terminal of the Buck Side Inductor Current

Sense Resistor (RSENSE). Ensure accurate current sense

with Kelvin connection.

VIN: Input Supply. The VIN pin must be tied to the power

inputtodeterminethebuck,buck-boost,orboostoperation

regions. Locally bypass this pin to ground with a minimum

1µF ceramic capacitor.

GND (Exposed Pad): Ground. Solder the exposed pad

directly to the ground plane.

LT8393EUFDM Datasheet(PDF) 12 Page - Analog Devices

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