TPS92830-Q1: Blinking functionality

matej617

Part Number: TPS92830-Q1
Other Parts Discussed in Thread: TIDA-01376, TIDA-01375

Hello,

I'm making blinking LED indicator using the TPS92830-Q1. I want it to blink at around 5Hz.

I used the TIDA-01376 for reference, because a turn indicator seemed similar to my application in terms of blinking frequency and required brightness.

http://www.ti.com/tool/TIDA-01376?keyMatch=null&tisearch=tidesigns#supportandcommunity

From reading the datasheets it was not apparent to me how the blinking function is actually implemented. What would be the best way to do it?

My first idea is to simply turn the device on and off at the required frequency. This would be achieved using an astable multivibrator controlling a PMOS between 12V and the IN pin.

Is there a better way to do it? Maybe with the PWM inputs?

Thanks and best regards,

Matej

over 5 years ago

0 Anda Zhang over 5 years ago

TI__Expert 5380 points

Using the PWM input will be a good idea or you can use the internal PWM generator (13uF + 14.2kohm), may i know the target application?

0 matej617 over 5 years ago in reply to Anda Zhang

Prodigy 40 points

It's an indicator light on top of a electric car(formula student)

0 matej617 over 5 years ago in reply to Anda Zhang

Prodigy 40 points

I have more questions concerning this driver. What is the motivation behind using the BUK763R8-80E MOSFET that's rated for 120A, if the driven current is only 300mA? I noticed a similar issue in the TIDA-01375 reference design, here's the quote: "In this design, the selected MOSFET is the NVD3055-150 in the DPAK package. This particular MOSFET is unable to support 300 mA of current for each channel.". I checked the datasheet and it says that the NVD3055-150 is rated for 9A. Why does the MOSFET have to be rated for currents that are a few orders of magnitude higher than the driven current. How do I pick a suitable MOSFET if I plan to drive 3 1W LEDs @ 300mA on each channel?

Best regards,

Matej

0 Anda Zhang over 5 years ago in reply to matej617

TI__Expert 5380 points

Thermal dissipation, for rear light application, worst case is 16V input voltage, 85C ambient temp, we have to keep junction temp of MOSFET within 150C, so normally the DDPAK can handle 300mA, DPAK can handle over 250mA.

0 matej617 over 5 years ago in reply to Anda Zhang

Prodigy 40 points

Will this design work? I want to use the internal pwm generator to dim the LEDs (400Hz, 10%) on top of that I want them to blink with the frequency set by the 555 timer.

0 Anda Zhang over 5 years ago in reply to matej617

TI__Expert 5380 points

yes, it works.

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TPS92830-Q1: Blinking functionality