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User20729
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Can the TLD1114-1EP be dimmed with an external PWM signal (on PWMI/EN/IN_SET pin) when the Power shift feature is used without external MOSFET?
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j_oehmen
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Moderator First like received 10 replies posted 5 replies posted
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When the TLD1114-1EP is used without the MOSFET no PWM dimming over PWMI, EN or IN_SET pin is possible. PWM operation over supply VS is possible as there the current path to the LEDs is disconnected by the switch supplying the module.
4891.attach

The reason is that the LEDs are always connected to the Power Shift resistor without an active switching element to disconnect - please see the picture above.
The current path (shown in green) is always closed as there is no switch to open it. This means even if you deactivate by EN/PWMI or INSET some current is flowing depending on the power shift resistor.
The current can be estimated with IOUT ~(VS - VLED)/(Rpowershift + Rshunt), where
- Rshunt = 750mOhm if OUTH is used
- Rshunt = 1500mOhm if OUTL is used.

This means that the only way to turn off the LEDs is to deactivate the power supply (as done e.g. in a fog light).

In case you want to do the wiping animation you will have to use the Power shift feature with a MOSFET.
See TLD1114-1EP Powershift appnote for further details:
https://www.infineon.com/cms/en/product/power/lighting-ics/litix-automotive-led-driver-ic/litix-basi...

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j_oehmen
Moderator
Moderator First like received 10 replies posted 5 replies posted
Moderator
When the TLD1114-1EP is used without the MOSFET no PWM dimming over PWMI, EN or IN_SET pin is possible. PWM operation over supply VS is possible as there the current path to the LEDs is disconnected by the switch supplying the module.
4891.attach

The reason is that the LEDs are always connected to the Power Shift resistor without an active switching element to disconnect - please see the picture above.
The current path (shown in green) is always closed as there is no switch to open it. This means even if you deactivate by EN/PWMI or INSET some current is flowing depending on the power shift resistor.
The current can be estimated with IOUT ~(VS - VLED)/(Rpowershift + Rshunt), where
- Rshunt = 750mOhm if OUTH is used
- Rshunt = 1500mOhm if OUTL is used.

This means that the only way to turn off the LEDs is to deactivate the power supply (as done e.g. in a fog light).

In case you want to do the wiping animation you will have to use the Power shift feature with a MOSFET.
See TLD1114-1EP Powershift appnote for further details:
https://www.infineon.com/cms/en/product/power/lighting-ics/litix-automotive-led-driver-ic/litix-basi...
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