Zxld1320 – Diodes ZXLD1320 User Manual

Page 4

ZXLD1320

Issue 1 - January 2008

www.zetex.com

Pin description

Name

Pin
#

Description

ADJ 1

Adjust input

• Leave floating, or connect to VREF to set 100% output current.
• Drive with dc voltage. (50mV

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 (V

ADJ

<28mV) to turn off device

(Standby mode)

BIAS

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 (R

BIAS

) from this pin to ground to reduce base

drive current (Reduced output current condition)

CFB

Control input/output for feedback control loop

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

compensation

POK

Power OK flag output

• Pin is high during normal operation.
• Pin switches low if the switch remains on for more than 500µs (nom)

ISENSE

Switch peak current sense pin

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

switch current (I

SWPEAK

)=0.05/R

EMITTER1

Switch emitters (Connect both pins to top of R

SENSE

to sense emitter current)

EMITTER2

COLLECTOR2

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

COLLECTOR1

M_LOAD

Load side input of high side current monitor.
Connect to sensing resistor RM.

N/C

Not connected locally

VIN

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

• Decouple to ground with capacitor close to device
• nominal average output (LED) current = 0.1/R

TADJ

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)

VREF

Internal 0.5V reference voltage output

Exposed Pad

Connect to Ground (0V)