LM3464 Datasheet, PDF (2/33 Pages) National Semiconductor (TI) – 4 Channel LED Driver Evaluation Board

LM3464, LM3464A
SNVS652F – APRIL 2010 – REVISED MAY 2013
Connection Diagram
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Figure 1. Top View
28-Lead TSSOP-28
Package Number PWP
PIN DESCRIPTIONS
Pin
Name
Description
Application Information
1
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.
2
DIM
PWM dimming control
Apply logic level PWM signal to this pin controls the average brightness of the
LED string. (<1.25V disable output).
3
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.
4 Thermal_Cap Thermal dimming ramp capacitor Connect a capacitor across this pin and GND to define the thermal dimming
frequency.
5
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.
6
DMIN
Minimum thermal dimming duty The voltage across this pin and GND defines the minimum thermal dimming
control
duty cycle.
7
Faultb
Fault signal output
Open Drain output, pull-down when FAULT condition occurred.
8
AGND
Signal ground
Analog ground connection for internal circuitry. Must be connected to PGND
external to the package.
9 FAULT_CAP Fault delay capacitor
Connect to an external capacitor to program the fault response time.
10
CDHC
DHC time constant capacitor
An external capacitor to ground programs the Dynamic Headroom Control loop
response time
11
OutP
DHC Output
Connect this pin to the voltage feedback input of primary power supply to
facilitate dynamic headroom control.
12
VLedFB Output voltage sense input
This pin senses the output voltage of the primary power supply.
13
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.
14
EN
Enable input
This pin serves as device enable input when logic level signal is applied. (Active
high with internal pull-up)
15
VIN
Supply voltage
The input voltage should be in the range of 12V to 80V for LM3464, 12–95V for
LM3464A
16
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.
17
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.
18
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.
2
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