Dears,
I have an important customer who is looking for an LED controller that can provide boost/buck for common anode laser R/G/B. Specific requirements are as follows: 1. The input voltage is 5V 2. The output voltage of R/G/B 3-channel LED is 2.5~3.1V/5.2~7V/4.8~6.5V. R/G/B outputs are enabled in turn separately
(any of the 2 channels will not be conducted at the same time), and the current is 300~500mA. 3. Due to cost pressure, they prefer to use one LED controller to switch the output through MOS as much as possible.
4. The R/G/B LED current considered is Common-anode topology, but if needed, the customer may change to common-cathode topology
I have discussed with TPS92365x AE, there seems no verified reference design currently that meets the above requirements (theoretically it should
be feasible, but the stability and reliability have not been tested). I think LM3421 can also support buck-boost, boost, and buck applications.
Can one LM3421 be used to meet customer needs? The input voltage range of LM3421 is 4.5~75V, but according to the block diagram, the internal LDO
is 6.9V. If the input is 5V, will it work normally? There is a buck-boost architecture in the specification book, and the output current is detected
at the cathode as a reference circuit:
Is it possible to multiplex the controller/circuit for the 3 outputs of 2.5~3.1V/5.2~7V/4.8~6.5V in time-division mode by switching output channels through 3 MOSs similar to Q2?
Please help to suggest the best solution. Relevant reference design documents are really appreciated.
Thank you so much!
