UCC2813-3: Bespoke, battery-powered PWM LED driver for IR point tracking application

Kieran Brown

Part Number: UCC2813-3
Other Parts Discussed in Thread: TL494

I am looking build an IR PWM LED driver using this IC. It meets all the requirements for my project unlike all the purpose-built LED driver ICs I have researched: too little power, too high voltage, too large a footprint, or too expensive. This a low cost, hobby project and I need it to work with relative ease, however I am struggling to simulate it with TINA. I am nearly finished studying to be an electronic engineer.

The problem I am having is the frequency at which the IC will switch at is very low: 60-75 Hz synced with a video camera. The frequency is set by an RC circuit, however there is no info on it's operation at such low frequencies. Is there any precedence for such low frequencies or any know issues? I am convinced it should work since no minimum frequency is listed in the documentation and only recommended passive component values, so it's worth a try.

over 7 years ago

0 Benjamin Lough over 7 years ago

TI__Mastermind 27095 points

Hi Kieran,

Thanks for your interest in UCC2813-3. 60-75Hz switching frequency is extremely low and would require very large magnetics. Why is it important to sync the switching frequency with a video camera in your application?

Best Regards,
Ben Lough

0 Kieran Brown over 7 years ago in reply to Benjamin Lough

Prodigy 110 points

I want to power the circuit with a battery and would like to maximize the battery life. The LED would ideally only turn on while the camera is capturing a frame. I could even vary the duty cycle to dim the LED without any wasted cycles.

This IC would not have a filter at the output. It would drive the LEDs directly. Another circuit will provide a power rail with a typical switching supply.

0 Benjamin Lough over 7 years ago in reply to Kieran Brown

TI__Mastermind 27095 points

Hi Kieran,

I understood your response to be you have a power supply design already and are looking for a way to enable/disable an LED and implement PWM dimming on the LED. Is this correct?

Best Regards,

Ben Lough

0 Kieran Brown over 7 years ago in reply to Benjamin Lough

Prodigy 110 points

Thanks for replying, Ben.
That's correct. Variable PWM generator - duty cycle control to dim and frequency matching and syncing - and power switch in one package.

0 Benjamin Lough over 7 years ago in reply to Kieran Brown

TI__Mastermind 27095 points

Hi Kieran,

What is the voltage of the supply rail you are using? Also what is the control signal you plan to use to dim the LED? Is it an analog voltage, I2C or something else?

Best Regards,
Ben Lough

0 Kieran Brown over 7 years ago in reply to Benjamin Lough

Prodigy 110 points

The supply voltage will be adjustable between 4.5 V and 9.0 V. It typically should operate between 4.5 V and about 6 V. 9 V is an extreme setting for experimental purposes. I will be using an analogue signal to control the LED duty cycle with a simple resistor voltage divider.

0 Benjamin Lough over 7 years ago in reply to Kieran Brown

TI__Mastermind 27095 points

Hi Kieran,

Take a look at TL494:www.ti.com/.../tl494.pdf. Figure 1 in the datasheet will provide you guidance for achieving the low switching frequency you requested.

Best Regards,
Ben Lough

0 Kieran Brown over 7 years ago in reply to Benjamin Lough

Prodigy 110 points

Hi Ben,

Sorry about the late response. I had considered the product you mentioned before, but it didn't meet my minimum specs. I have double-checked the minimum voltage and current limit specs to match my LEDs and it looks like it should work with some refinement of my specs plus it's way cheaper. I think it's a safer choice. Thank you for the help.

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UCC2813-3: Bespoke, battery-powered PWM LED driver for IR point tracking application