ZXLD1320 Ver la hoja de datos (PDF) - Zetex => Diodes

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componentes Descripción

Fabricante

ZXLD1320

Buck mode DC-DC converter for LED driving with 1.5A output and current control

Zetex => Diodes 

ZXLD1320

Pin description

Name

ADJ

BIAS

CFB

POK

ISENSE

EMITTER1

EMITTER2

COLLECTOR2

COLLECTOR1

M_LOAD

N/C

VIN

TADJ

VREF

Exposed Pad

Pin Description

#

1 Adjust input

• Leave floating, or connect to VREF to set 100% output current.

• Drive with dc voltage. (50mV<VADJ< VREF) to adjust output current

from 10% to 100% of set value. (DC brightness control mode)

• Drive with low frequency (200Hz) PWM control signal to gate output

‘on’ and ‘off’ at the PWM frequency. (PWM brightness control mode)

• Drive with low level dc voltage (VADJ<28mV) to turn off device

(Standby mode)

2 Bias pin for setting base current of internal switch transistor

• Short pin to ground to define maximum base drive current for

output switch (Maximum output current condition)

• Connect resistor (RBIAS) from this pin to ground to reduce base

drive current (Reduced output current condition)

3 Control input/output for feedback control loop

• Connect 10nF capacitor from this pin to ground to provide loop

compensation

4 Power OK flag output

• Pin is high during normal operation.

• Pin switches low if the switch remains on for more than 500µs (nom)

5 Switch peak current sense pin

• Connect resistor (Rsense) from this pin to ground to define peak

switch current (ISWPEAK)=0.05/RS

6

7 Switch emitters (Connect both pins to top of RSENSE to sense emitter current)

8

9 Switch Collectors (Connect both pins to lower side of coil)

10 Load side input of high side current monitor.

Connect to sensing resistor RM.

11 Not connected locally

12 Positive supply to device (4-18V) and sensing resistor RM

• Decouple to ground with capacitor close to device

• nominal average output (LED) current = 0.1/RM

13 Temperature Adjust input for LED thermal compensation

• Connect thermistor/resistor network to this pin to reduce output

current above a preset temperature threshold.

• Connect to VREF to disable thermal compensation function

(see section on temperature control for details)

14 Internal 0.5V reference voltage output

15 Connect to Ground (0V)

Issue 1 - January 2008

4

© Zetex Semiconductors plc 2008

www.zetex.com

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