DP83822I: LED connection

g.f.

Part Number: DP83822I

Hi,

I have a question about LED pin connections of DP83822I.

I want to setup strap pin LED_0 to MODE 4(AN_0=1)which is default and
LED_0 pin will be connected to LED.
From DP83822 datasheet, resistor RH and RL can be open for setting LED_0 pin to Mode 4.
So, I think the circuit will be like attached file page.1

And also I'm going to connect LED_1 pin to LED as attached file page.1
But I'm not clear that my circuit are correct or not for both cases(LED_0&LED1).

In datasheet page.50 "8.5.2 LED Configuration", it said that parallel resistors are required.
Should I put parallel resistor on LED_0 line and LED_1 line as like attached file page.2 for my use case?
If yes, what value of resistor should be used?

DP83822I LED Connection.pptx

best regards,
g.f.

over 6 years ago

0 Hung Nguyen92 over 6 years ago

TI__Expert 5670 points

Hi G.F.,

A parallel resistor is required when connecting LED_0 and LED_1 pins to LED. As mentioned in the datasheet, a 1.96kΩ to 2.49kΩ resistor should be used as the parallel pull resistor.

On our EVM, 2.49kΩ resistor is used, similar to what you have on page 2 of your attachment.

Regards,

Hung Nguyen

0 Hirotaka Matsumoto over 6 years ago in reply to Hung Nguyen92

Guru 27585 points

Hung san

In relation to this question, we would like to confirm one point.
If there is no parallel resistor, will the mode be unstable?

Kind regards,

Hirotaka Matsumoto

0 Hung Nguyen92 over 6 years ago in reply to Hirotaka Matsumoto

TI__Expert 5670 points

Hi Hirotaka,

The pin voltage during hardware reset matters and will determine the polarity of the LED pins. The parallel resistor is required to prevent bootstrapping to Mode 2 or Mode 3.

Regards,

Hung Nguyen

0 Hung Nguyen92 over 6 years ago in reply to Hung Nguyen92

TI__Expert 5670 points

Hi Hirotaka,

I haven’t heard back from you. I’m assuming you had the answers to your questions.

I will go ahead and close this thread. If you need further support, kindly open a new thread.

Regards,

Hung Nguyen

0 Hirotaka Matsumoto over 6 years ago in reply to Hung Nguyen92

Guru 27585 points

Hung san

Thank you so much for your help!
And, we appologize that we are late for reply.
OK, we got it.

Kind regards,

HIrotaka Matsumoto

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DP83822I: LED connection