ZXLD1321 Ver la hoja de datos (PDF) - Zetex => Diodes

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Fabricante

ZXLD1321

Boost mode DC-DC converter for LED driving with 1A output and current control

Zetex => Diodes 

ZXLD1321

Pin description

Name

ADJ

BIAS

CFB

N/C

ISENSE

EMITTER

COLLECTOR

M_LOAD

M_VIN

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 Compensation point

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

compensation

4 No connection to this pin (open circuit)

5 Switch peak current sense pin

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

switch current (ISWPEAK)=VSENSE/RSENSE

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

11 Input supply to high side current monitor

• Connect to output voltage (cathode of Schottky)

• Connect resistor (RM) between M_LOAD and M_VIN to define

nominal average output (LED) current of 0.1/RM

12 Positive supply to device (1.2-12V)

• Decouple to ground with capacitor close to device

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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