Looking for low-cost LED driver with selectable PWM ramp and blink

Anindo Ghosh

Other Parts Discussed in Thread: TPS75105, TL4242, LP5521, LP5560

Hi,

Would anyone have any suggestions for a very basic LED driver, with current regulation (boost not needed), that generates a selectable PWM on / off slope, and selectable blinking?

I am looking for

something low-cost
Current in the 20 mA range, voltage in the 3.3 V range preferred
either a SOIC, SC70, or similar leaded package, not a BGA or leadless package
a minimum number of pins and bare-minimum functionality / complexity
I2C or pull-up resistors for mode selection - this will be controlled from an MSP430 (or hard-wired)
Programming / mode selection should need no input once set up, and blinking should need no further input
Should not need PWM to be fed to it, must generate it internally
Fade-in and fade-out ramp options for exponential curve, I don't need linear.

Ideally, is there any TI or National IC similar to the Fairchild FAN5646? The ICs I could find via parametric search are much more complex in functionality, and are in packages not amenable to hand-soldered prototyping.

Any help appreciated. Thank you.

Warm Regards

over 11 years ago

0 Vincenzo Pizzolante over 11 years ago

TI__Mastermind 22736 points

I couldn't see any exact pin2pin part, but similar (in functionality)...

have a look at the http://www.ti.com/product/tps75105 and http://www.ti.com/product/tl4242

Vincenzo

0 Anindo Ghosh over 11 years ago in reply to Vincenzo Pizzolante

Prodigy 40 points

Hi,

Thank you for your response.

Neither of these parts has functionality similar to the described requirement / Fairchild FAN5646:

* TPS75105 requires external PWM, does not have a self-running fade cycle

* TL4242 is not really in that product space, it is for high current applications, and also does not have a self-running fade cycle.

I do appreciate your suggestions though.

Warm Regards

Anindo Ghosh

0 Vincenzo Pizzolante over 11 years ago in reply to Anindo Ghosh

TI__Mastermind 22736 points

well, we have LM5522 but it doesn't come in SOT/SC/SON package,

it is a BGA, and I excluded it in advance

Vincenzo

0 Sami Kotijarvi over 11 years ago

TI__Intellectual 2510 points

Hi,

I would recommed the Lp5521, but it is also available only in BGA and LLP packages. Do you have only soldering iron, which you use for hand-soldering? Could you use the Evaluation Modules for prototyping?

Regards,

Sami

0 Anindo Ghosh over 11 years ago in reply to Sami Kotijarvi

Prodigy 40 points

Hi,

Thanks, this part is somewhat closer to what I am looking for - It could potentially be programmed to ramp up / down (breathe) similar to the FAN5646, it seems. The package remains a problem, not just due to the micro-SMD package (the EVM solves that), but also the rather more complex pin-out and external resistors requirement.

I'll mark this answer as accepted, since it seems the closest and there really isn't TI any product with the minimal pin-out and features of the Fairchild part, apparently.

The sheer elegance of the FAN5646 approach still serves our purposes way better, so we will stick with that.

Thank you all.

Warm Regards

Anindo

0 Sami Kotijarvi over 11 years ago in reply to Anindo Ghosh

TI__Intellectual 2510 points

Hi,

With LP5521 there are only the I2C pull-up resistors needed. With LP5521 You have more complex lighting patterns than just ramp up/ramp down. If you do not use the chargepump and drive the LEDs from battery, the fly-caps and c out cap can be removed.

There is also LP5560 part, which is a 4-pin BGA driver for 1 LED output. The pin-out is similar to the FAN5646 (pin A1=VDD, A2=LED, B1=GND, B2=CTRL). Sorry that I missed this earlier.

Regards,

Sami

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Looking for low-cost LED driver with selectable PWM ramp and blink