Driving An Incandescent Lamp - Danfoss PLUS+1 Technical Information

Technical Information
Driving a Relay or ON/OFF
Valve (continued)
Driving an Incandescent
Lamp
6
Output Configurations for PLUS+1® Controllers
Use sourcing or sinking when there are other sources tied in parallel, such as a
jog switch.
+Batt
Sourcing
Con guration
Ground
+Batt
Sourcing
Con guration
Ground
Danfoss only recommends using a digital output for driving incandescent lamps. This encompasses
outputs labeled as DOUT or DOUT/PVG Pwr. These outputs always provide a high voltage (sourcing
battery voltage) as the output when in the ON state.
+Batt
Ground
It is not recommended to use multi-function PWM outputs for driving incandescent lamps. There are
limitations when driving incandescent lamps from multi-function outputs. An incandescent lamp has
an "inrush" current. Inrush is a spike in current just as you turn the lamp on when the filament is cold.
Multi-function outputs have a hard current limit which will trip the output off if this limit is exceeded.
When driving an incandescent lamp this can happen even though the average current requirements
for the lamp are well within the output pin's drive capability. Depending on the inrush current, it
cannot be guaranteed that the multi-fuction output will reliably drive an incandescent lamp. This has
sometimes been effectively addressed by setting the output to open loop PWM (PinConfig = 3) and
then ramping the PWM percentage from 0 to 100 percent, but this is not guaranteed to work for all
applications.
520L0922 • Rev EA • Sep 2013
FET
Logic circuits
FET
FET
Logic circuits
FET
FET
Logic
circuits
+Batt
Single Pole
Single Throw
Switch
2395
+Batt
Single Pole
Double Throw
Switch
2396
Lamp
2298