zxld1360 Zetex Semiconductors plc., zxld1360 Datasheet - Page 22

• Manufacturer Part Number: zxld1360
• Description: 1a Led Driver With Internal Switch
• Manufacturer: Zetex Semiconductors plc.

Note that the device power dissipation will most often be a maximum at minimum supply
voltage. It will also increase if the efficiency of the circuit is low. This may result from the use of
unsuitable coils, or excessive parasitic output capacitance on the switch output.
Thermal compensation of output current
High luminance LEDs often need to be supplied with a temperature compensated current in order
to maintain stable and reliable operation at all drive levels. The LEDs are usually mounted
remotely from the device so, for this reason, the temperature coefficients of the internal circuits
for the ZXLD1360 have been optimized to minimize the change in output current when no
compensation is employed. If output current compensation is required, it is possible to use an
external temperature sensing network - normally using Negative Temperature Coefficient (NTC)
thermistors and/or diodes, mounted very close to the LED(s). The output of the sensing network
can be used to drive the ADJ pin in order to reduce output current with increasing temperature.
Issue 1 - March 2007
© Zetex Semiconductors plc 2007
1100
1000
900
800
700
600
500
400
300
200
100
0
-50
-30
-10
Maximum Power Dissipation
10
Ambient Temperature (Deg C)
30
22
50
70
90
110
130
150
ZXLD1360
www.zetex.com