TLVH431A-Q1: CATHODE pin voltage when OV protection

Frank QIN

Part Number: TLVH431A-Q1
Other Parts Discussed in Thread: TLVH431

Hi Team,

We are using TLVH431AQDBVRQ1 in a ADAS project for 3.3V rail overvoltage detection and shut down. The overvoltage threshold is set as 4V typical. The schematic is shown as below, the CATHODE pin resistance is 3.01k. During the test, we found the voltage against GND is 0.86V when overvoltage protection is triggered. Which is lower than the value in the datasheet(Vref=1.209V-1.271V). After calculation, the current flows in the CATHODE pin is 0.8mA(aligned with the datasheet 0.1~70mA range). Please kindly advise why this voltage can lower than the datasheet value.

Do we have this "current--temperature--VKA voltage" curve? We are using the TLVH431 as open loop mode, need to analyze the WCCA.

Please also kindly share us if there are other calculation materials and tools.

Thanks!

Frank

11 months ago

0 Joshua Garcia 11 months ago

TI__Expert 5450 points

Hi Frank,

Can you confirm the value of the voltage at the cathode pin?

Also during normal operation (VCC=3.3V) what voltage do you see at the REF pin?

Thanks,

Joshua

0 lixia jia 11 months ago in reply to Joshua Garcia

Prodigy 30 points

Hi Joshua

1、the voltage of cathode-gnd is 0.86V.the voltage of Vref-gnd is 1.34V.

2、Our application scenario is open loop of TLVH431，We want to know the "voltage - current - temperature relationship" of the TLVH431 when the open loop "low" mode as follow:

0 Joshua Garcia 11 months ago in reply to lixia jia

TI__Expert 5450 points

Hi Lixia,

Thank you for your clarification.

In this case an open loop comparator output response comparing Vin and Vout would be the appropriate answer here. This can be found in the industrial TLVH431 datasheet (https://www.ti.com/lit/ds/symlink/tlvh431b.pdf?ts=1695790648421&ref_url=https%253A%252F%252Fwww.google.com%252F) on page 18 section 9.2.1.3 Application Curves. As you can see from figure 9-4 the Vout = Vcathode-gnd = roughly less than one, meaining the 0.86V that you are observing is the expected output.

Thanks,

Joshua Garcia

0 lixia jia 11 months ago in reply to Joshua Garcia

Prodigy 30 points

thank you for response

we need to analyze the WCCA of TLVH431,can you share us the influence of full temperature range and IKA(current) .The case in the specifications is not clear enough.

0 Joshua Garcia 11 months ago in reply to lixia jia

TI__Expert 5450 points

Hi Lixia,

We do not have that data.

We do however have a supervisor, TPS3760E012DYYRQ1, which could help to simplify your circuit. This is an adjustable overvoltage supervisor that would be set to monitor your 3.3V rail for the 4V OV threshold condition and provide a corresponding reset signal.

Thanks,

Joshua

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TLVH431A-Q1: CATHODE pin voltage when OV protection