LM3464 datasheet(2/34 Pages) TI2

2 / 34 page

LM3464, LM3464A

SNVS652F – APRIL 2010 – REVISED MAY 2013

www.ti.com

Connection Diagram

Figure 1. Top View

28-Lead TSSOP-28

Package Number PWP

PIN DESCRIPTIONS

Name

Description

Application Information

SYNC

Synchronization signal output for

Connect this pin to the DIM pin of other LM3464/64A to enable cascade

cascade operation

operation (multiple device). This pin should leave open for single device

(Master-Slave configuration)

operation.

DIM

PWM dimming control

Apply logic level PWM signal to this pin controls the average brightness of the

LED string. (<1.25V disable output).

Thermal

Thermal sensor input

Connect thermal sensor to this pin with bias accordingly to facilitate thermal

foldback and control the brightness of the LED array.

Thermal_Cap

Thermal dimming ramp capacitor

Connect a capacitor across this pin and GND to define the thermal dimming

frequency.

VDHC

Head room control

Apply external voltage across this pin and ground to define the minimum drain

voltage. This pin is internal biased at 0.9V.

DMIN

Minimum thermal dimming duty

The voltage across this pin and GND defines the minimum thermal dimming

control

duty cycle.

Faultb

Fault signal output

Open Drain output, pull-down when FAULT condition occurred.

AGND

Signal ground

Analog ground connection for internal circuitry. Must be connected to PGND

external to the package.

FAULT_CAP

Fault delay capacitor

Connect to an external capacitor to program the fault response time.

CDHC

DHC time constant capacitor

An external capacitor to ground programs the Dynamic Headroom Control loop

response time

OutP

DHC Output

Connect this pin to the voltage feedback input of primary power supply to

facilitate dynamic headroom control.

VLedFB

Output voltage sense input

This pin senses the output voltage of the primary power supply.

VCC

Internal regulator output

This pin is the output terminal of the internal voltage regulator and should be

bypassed by a high quality 1uF ceramic capacitor.

Enable input

This pin serves as device enable input when logic level signal is applied. (Active

high with internal pull-up)

VIN

Supply voltage

The input voltage should be in the range of 12V to 80V for LM3464, 12–95V for

LM3464A

DR4

Channel 4 drain sense input

This pin senses the drain voltage of the external MOSFET of channel 4 to

facilitate DHC operation and fault detection.

DR3

Channel 3 drain sense input

This pin senses the drain voltage of the external MOSFET of channel 3 to

facilitate DHC operation and fault detection.

DR2

Channel 2 drain sense input

This pin senses the drain voltage of the external MOSFET of channel 2 to

facilitate DHC operation and fault detection.

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