TDE1747 Input terminals reflecting supply voltage

[Praveenv]

Hello,

I built a test circuit similar to one provided in the TDE1747 datasheet (Figure 3). During testing, I observed that immediately after powering on, the power supply voltage appears at both inverting and noninverting terminal of the IC. This behaviour is consistent across two different TDE174 ICs.

Could you please help identify the possible root cause of this issue?

 

Thank You.

[Joe WILLIAMS]

Hi Praveenv

 

This post has been escalated to the ST Online Support Team for additional assistance.  We'll contact you directly.

 

Regards

Joe

STMicro Support

[Andrew Neil]

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@Praveenv wrote:

I built a test circuit similar to one provided in the TDE1747 datasheet (Figure 3).

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How "similar" ?

Please show the actual circuit that you used.

Also some good, clear photos of how you implemented it.

 

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@Praveenv wrote:

I observed that immediately after powering on, the power supply voltage appears at both inverting and noninverting terminal

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How, exactly, did you observe that?

[Praveenv]

Hello Andrew Neil,

Thanks for the reply, The exact scenario is explained below. I hope it will help you.

The implementation circuit is exactly same as shown below.

The values used are as follows:

- Rsense: 1.2ohm

- Rload: 280ohm

- Reference voltage at inverting terminal is set to 1.95V (VCC: 28V, Rtop: 100kohm , Rbottom: 7.5lohm)

Test execution procedure is as follows:

1. Turned on the supply

2. Probed to check whether reference voltage is generated properly or not. Then probed the output and observed that output voltage is 28V (expected was 0V).

3. Then applied the input voltage (5V) greater than vref (1.95) at Non-Inv terminal and observed that the reference voltage is shifted to 6V and output voltage is 28V.

 

[Andrew Neil]

Photos?