zxld1362 Zetex Semiconductors plc., zxld1362 Datasheet - Page 22

• Manufacturer Part Number: zxld1362
• Description: 1a Led Driver With Internal Switch
• Manufacturer: Zetex Semiconductors plc.

Shutdown mode
Taking the ADJ pin to a voltage below 0.2V for more than approximately 100µs, will turn off the
output and supply current will fall to a low standby level of 65µA nominal.
Note that the ADJ pin is not a logic input. Taking the ADJ pin to a voltage above V
output current above the 100% nominal average value. (See page 18 graphs for details).
Soft-start
An external capacitor from the ADJ pin to ground will provide a soft-start delay, by increasing the
time taken for the voltage on this pin to rise to the turn-on threshold and by slowing down the
rate of rise of the control voltage at the input of the comparator. Adding capacitance increases this
delay by approximately 0.2ms/nF. The graph below shows the variation of soft-start time for
different values of capacitor.
Actual operating waveforms [V
Soft-start operation. Output current (Ch2) and LX voltage (Ch1)
Issue 1 - December 2007
© Zetex Semiconductors plc 2007
16
14
12
10
-2
8
6
4
2
0
0
Soft Start Time vs Capacitance from ADJ pin to Ground
IN
20
=24V, R
40
S
=0.1 , L=68µH, 22nF on ADJ]
Capacitance (nf)
22
60
80
100
120
ZXLD1362
www.zetex.com
REF
will increase