Newbie to electronics here.
Referencing Allegro’s A6211 LED driver, I’m planning a circuit that uses the “typical circuit” example in the data sheets for both this IC and the IC evaluation board APEK6211GLJ-01-T-DK. Amazingly, the circuits in the two data sheets are pretty much identical, which gives me some confidence in the examples.
The environment: 1) DC power supply is 12.6V to 13.5V, typically the latter (automotive); 2) LED is Cree XHP70.2 with Vf of 11.6V and a max current of 2.4A: 3) R1, which controls the switching freq will be 240 KOhm to achieve a lower freq of 300 KHz; 4) Rsense will be .08 Ohm to achieve a 2.5A CC output: and 5) there will be a 5V relay between the power source and C1 (47uF 50V) that filters/conditions for Vin.
- this IC, of course, is buck topology - can I get 11.6V out of the 13.5 input? There is a graph in the DS that indicates that at the lower freqs (300 KHz), the output V can be as high as .9167 of the input voltage.
- reading the DS, I think the inductance value should be between 22uH and 33uH - what say you all?
- for the relay, was thinking of using a G5Q-1A4-EL2-HA-DC5 (not in DigiKey’s system) to enable blinking capabilities. What problems am I introducing to this circuit with this relay? Is there a better place to insert the relay? BTW, the relay will be switched by a PIC10F200 off of a GPI/O pin with a amp circuit to get up to the requirements of the relay.
Advance thanks to all that contribute.