Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsDev KitsPCB design board

VIN

COMP

CSH

RCT

AGND

OVP

nDIM

FLT

TIMR LRDY

DPOL

PGND

GATE

VCC

RPD

HSP

HSN

DDRV

www.ti.com

LM3423 TSSOP Pin Connection

Table 3. LM3423 Evaluation Board Test Points

Test Point Designation Function or Use

TP1 Test point for "LED+" connector (LED anode).

TP2 Test point for "LED-" connector (LED cathode).

TP3 Test point for regulated output voltage.

TP5 Test point for L-RDY pin.

TP6 Test point for "PWM Dimming" input signal.

TP7 Test point for IS pin.

TP8 Test point for nDIM pin.

TP9 Test point for FLT pin.

TP10 Test point for GROUND.

TP11 Test point for TIMR pin.

TP12 Test point for switch-node.

4 LM3423 TSSOP Pin Connection

Figure 1. Top View

LM3423 Pin Connection

5 Board Features

This evaluation board has all the necessary connections and jumpers to evaluate the LM3423 controller in

a boost converter topology with the following operating features and options:

5.1 Setting Average LED Current

The LM3423 uses peak current-mode control to regulate the boosted output voltage. An external current

sense resistor R

SENSE

(i.e. R9) in series with the LED load is used to convert the LED current, I

LED

, into a

voltage that is sensed by HSP (pin 19) and HSN (pin 20). HSP and HSN are the inputs to a high side

sense amplifier that is used in combination with a resistor tied to CSH (pin 4) and an error amplifier to

program a desired I

LED

current.

SNVA376A–December 2008–Revised May 2013 AN-1907 LM3423 Buck-Boost Configuration Evaluation Board

Submit Documentation Feedback