Using MC34063A for White LED drive of 8 strings of 3 LEDs each with brightness control

BrandonAzbell

Other Parts Discussed in Thread: MC34063A, TPS61165

The topic of using a MC34063A for LED drive has been brought up before. Certainly, the MC34063A can be used in a boost converter topology to drive a string of White LEDs.

However, if it is possible to implement a brightness control with the MC34063A, how would that be done? I realize there are other solutions available to do this very thing, but those options have more features than needed.

The particular application will have the following characteristics.

Vin(dc) = 3.3V or 5.2V
Vout(dc) = 9.9V typ and 10.8 max
Iout = 160mA

There is no need to control each string of 3 LEDs individually, but treat the entire assembly as a single string (just know that it is configured as 8 strings of 3 LEDs).

over 14 years ago

0 Matthew Day over 14 years ago

TI__Mastermind 36110 points

There are several options for dimming LED when using the MC34063A. One is to inject a voltage into the feedback circuitry. The higher the injected voltage, the lower the LED current. You can also achieve PWM dimming by turning the circuit on and off at frequencies greater than 60 Hz. For an LED driver application, I would like to suggest that you review our extensive line of LED driver ICs. These dedicated ICs are designed specifically for driving LEDs so they will most likely be more suited for the application. They will be much easier to design with, have a smaller solution size, and be more efficient. The following link will direct you to a selection tool for our LED driver ICs.

http://focus.ti.com/paramsearch/docs/parametricsearch.tsp?family=analog&familyId=691&uiTemplateId=NODE_STRY_PGE_T

0 Jan Switzky over 14 years ago in reply to Matthew Day

Prodigy 125 points

Thanks for your reply. I tried using the selection tool, but can't find a part that fits the requirement very well. I also want to keep the solution price to around $1.50 if possible. I see there is a new part (TPS61069B0) that could work, but the price is not listed.

Regards,

Jan Switzky

0 Jeff F over 14 years ago in reply to Jan Switzky

TI__Guru**** 167806 points

Try TPS61165.

Power management

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Using MC34063A for White LED drive of 8 strings of 3 LEDs each with brightness control