TPD3S713-Q1: IMON output clamp

Shinji Tsuji

Genius 14119 points

Part Number: TPD3S713-Q1

Hi team,

I plan to connect IMON output to ADC in MCU(3.3V).

RILIM=6.98kohm, RIMON=5.6kohm

Since MCU input tolerance is 3.3V, I need to limit the VMON voltage less than 3.3V.

I concerns the voltage spike caused by inrush current to VBUS might violate 3.3V output.

Could you advise below?

1. How does IMON output behave when large inrush current flows? It is described that high current flaws for 1 to 2us(typical) before current limit circuit react in the datasheet?

2. Should I use clamp diode externally?

3. How much is the current limit (maximum current) out from IMON?

regards,

over 3 years ago

0 Kuno Wu over 3 years ago

TI__Mastermind 18556 points

Hi Tsuji-san,

1.Yes, according to our block diagram, it will have a same behavior with 'current sense', they use a same source, only the current source is different.

2.You can reserve a clamp diode to make sure your MCU safe.

3.You can refer to below spec.

Best Regards,

Kuno

0 Shinji Tsuji over 3 years ago in reply to Kuno Wu

TI__Genius 14119 points

Hi Kuno-san,

Could you advise or give me a test result of the IMON output showing shorted output?

If the spike is only 1 or 2us, then it can be filter out by small capacitor to GND.

For #3, This is the tolerance of current output when current is clamped, correct? I would like to know the maximum peak current if large inrush current flows when the device is enabled.

regards,

0 Kuno Wu over 3 years ago in reply to Shinji Tsuji

TI__Mastermind 18556 points

Hi Tsuji-san,

Sorry, I go out to have a test this morning, I will have a test using our EVM this afternoon, I will give you feedback later, thanks.

Best Regards,

Kuno

0 Kuno Wu over 3 years ago in reply to Shinji Tsuji

TI__Mastermind 18556 points

Hi Tsuji-san,

You said that you set the RILIM=6.98kohm, RIMON=5.6kohm, could you please tell me which the ILIM you mean? Or please tell me what is your set up for the below pin:

Thank you very much.

Best Regards,

Kuno

0 Shinji Tsuji over 3 years ago in reply to Kuno Wu

TI__Genius 14119 points

Hi Kuno-san,

I don't think there is not difference between ILIM High and Low, correct?

In that case, either ILIM is fine.

Please use ILIM High.

J6 = Open, R14=6.98kohm

Please probe IMON voltage and VBUS current at the same picture.

It is helpful to see if C13 helps mitigating the peak or not.

regards,

0 Kuno Wu over 3 years ago in reply to Shinji Tsuji

TI__Mastermind 18556 points

Hi Tsuji-san,

I don't think there is not difference between ILIM High and Low, correct?--Yes.

Got it, I will have a quick test, and let you know the result.

Best Regards,

Kuno

0 Kuno Wu over 3 years ago in reply to Shinji Tsuji

TI__Mastermind 18556 points

HI Tsuji-san,

I have set up R14=6.98kohm, Rimon=5.6kohm, and let the Iload from 0.5A to shorted, below is my test result:

It seems that it is ok when the Vout is shorted, and for question3, this value is only for the Iload=0.5A, and we do not have this parameter in our datasheet.

Best Regards,

Kuno

0 Shinji Tsuji over 3 years ago in reply to Kuno Wu

TI__Genius 14119 points

Hi Kuno-san,

Could you test no load (VBUS=0V) to switch on?

I would like to see the affect of the inrush current flow into output capacitor.

regards,

0 Shinji Tsuji over 3 years ago

TI__Genius 14119 points

The customer concerns the spike on IMON pin caused by inrush current to VBUS output capacitor when the VBUS is enabled.

No need to short the output. 700mA load current should be enough to hit the current limit.

regards,

0 Shinji Tsuji over 3 years ago in reply to Shinji Tsuji

TI__Genius 14119 points

By the way why does IMON pin drops when VBUS is short to GND?

regards,

0 Kuno Wu over 3 years ago in reply to Shinji Tsuji

TI__Mastermind 18556 points

I need to power on using the VIN or the EN? and what is the load need?

0 Shinji Tsuji over 3 years ago in reply to Kuno Wu

TI__Genius 14119 points

Use EN pin.

Load is 1. Open, 2. 700mA, 1A.

Could you test those 3 scenario?

regards,

0 Kuno Wu over 3 years ago in reply to Shinji Tsuji

TI__Mastermind 18556 points

Tsuji-san,

I guess in the 1 condition, the device is shut down due to the output shorted, so the IMON drops in this time, then in the 2 condition, the device try to open, but the current still limit to the configuration, so IMON go to high again, just is my assumption.