I have been working with the TPS54200, we originally chose this part because we really liked how accurate the data sheet said it was at low pwm which seems to track with what we have validated in house. We have gotten feedback that the LEDs we are driving are too bright for the application. I am hoping that you and your team can advise on some component value changes that might help us out or an alternative LED driver for our application.
Design Requirement:
- Constant current driving
- PWM input control
- drive 2 LEDs in series Vf stack of 5.4V
- max current of3mA - 5mA(originally this was 20mA) some additional verification needed
Open Questions:
- How capable is this driver at low currents?
- are we outside an applicable use case here?
- What are our margins for error here what can we do to improve the accuracy of the feedback at low currents?
Current areas of flexibility:
- Vin/VLED = 10V we can change this
- Any of the passive we can change these
- PWM logic level can change
- PWM frequency we can change this as well currently 20kHz we have verified up to 50kHz but confident we can go to 100kHz
- new driver this is possible we have in house stock of the TPS54200, but alternative suggestions are welcome
