TPS4H160-Q1: Automatic retry time after open-load detection

Tomoaki Yoshida91

Genius 5255 points

Part Number: TPS4H160-Q1

Hi team,

I have a question.

How long time maximum automatic retry time after open-load detection?

It is written that the open-load detection and short-to-battery detection are same mechanism.

Does that mean that these two conditions can not be distinguished from each other?

Best regards,

Tomoaki Yoshida

over 7 years ago

0 Mahmoud Harmouch over 7 years ago

TI__Mastermind 28260 points

Hello,

Detail explanation will be sent beginning of next week.

0 Tomoaki Yoshida91 over 7 years ago in reply to Mahmoud Harmouch

Genius 5255 points

Hi Mahmoud-san,

Thank you for your quick response.

I will be waiting for your reply.

Best regards,

Tomoaki Yoshida

0 Tomoaki Yoshida91 over 7 years ago in reply to Tomoaki Yoshida91

Genius 5255 points

Hi Mahmoud-san,

Any update on this?

If you have any updates please let me know.

Best regards,

Tomoaki Yoshida

0 Mahmoud Harmouch over 7 years ago in reply to Tomoaki Yoshida91

TI__Mastermind 28260 points

Hello Yoshida-san,

I am planning to work on this question and send you the answer today.

Regards, Mahmoud

0 Mahmoud Harmouch over 7 years ago in reply to Mahmoud Harmouch

TI__Mastermind 28260 points

Yashida-san,

On state ie IN is high:
The only signal changing is the CS. Open load, CS goes to 0V immediately and by reconnecting the load CS goes to its level immediately. The FAULT signal stays high in both cases

OFF state ie IN is low:
Both signals CS and FAULT change. Open load CS goes to 0V and FAULT goes to High immediately. Reconnecting the load CS goes high and FAULT goes low immediately.
Short to battery, after 500uS from the short CS goes high and FAULT goes low.

Regards,

0 Tomoaki Yoshida91 over 7 years ago in reply to Mahmoud Harmouch

Genius 5255 points

Hi Mahmoud-san,

Thank you for your support.

We are concerned about the off state, that is INx is low.

In our system, it seems that a fault has been detected when INx has turned to low because load impedance is high.

So the load is active device, it may be shutdown, in that case it will be in a high impedance state and the discharge of Vout will be slow.

In this case, while Vvs - Vout <V(ol, off), VCS outputs High, Vfault is Low, and at the moment Vvs - Vout> V(ol, off), Vfault returns to High.

Is the condition for canceling the fault state Vvs - Vout> V (ol, off)?

Does V(ol, off) have hysteresis?

Best regards,

Tomoaki Yoshida

0 Mahmoud Harmouch over 7 years ago in reply to Tomoaki Yoshida91

TI__Mastermind 28260 points

Hello Yoshida-san,

I have measured the states for VCS and VFAULT during VS - VOUT transition around V(OL,OFF). Here is the test result:

1- VS - VOUT < V(OL,OFF), VCS is high and VFAULT is low

2- VS - VOUT = V(OL,OFF), VCS is low and VFAULT is high. V(OL,OFF) measured 2.1V

3- VS - VOUT =1.94V, VCS is low and VFAULT is high

4 VS - VOUT = 1.93V, VCS is high and VFAULT is low

The measured hysteresis is 2.1V - 1.93V = 170mV

Hysteresis is not defined in the datasheet but it looks like it is there.

Regards, Mahmoud

0 Tomoaki Yoshida91 over 7 years ago in reply to Mahmoud Harmouch

Genius 5255 points

Hi Mahmoud-san,

Thank you for your support.

I understood there is hysteresis voltage.

Does the condition for entering open - load detection be 1.93 V, and the condition under which open - load detection is canceled is 2.1 V?

Best regards,

Tomoaki Yoshida

0 Tomoaki Yoshida91 over 7 years ago in reply to Tomoaki Yoshida91

Genius 5255 points

Hi Mahmoud-san,

I have an additional question.
If the external pull-up resistor is not connected at the open load, fault detection is made by leakage current and I'm recognizing that diagnosis can not be performed at the CS pin.
If there is no pull-up resistor, is there any other influence?
Please tell me if there are other concerns.

Best regards,
Tomoaki Yoshida

0 Mahmoud Harmouch over 7 years ago in reply to Tomoaki Yoshida91

TI__Mastermind 28260 points

Hello Yoshida-san,

In open load condition when the IN is low (channel disabled), the FET is high impedance but at the same time the open load is much higher impedance. Suppose Zfet is the FET impedance and Zload is the open load impedance, Vds = Vs x Zfet/(Zfet + Zload). If Zload >> Zfet, the Vds is lower than V(ol,off). But if there is leakage from OUT to ground due to moisture, Zload is lower and VDS may be higher than V(ol,off)

Regards, Mahmoud

0 Mahmoud Harmouch over 7 years ago in reply to Tomoaki Yoshida91

TI__Mastermind 28260 points

Yoshida-san, that is right. This is what my bench test shows.

Regards

0 Tomoaki Yoshida91 over 7 years ago in reply to Mahmoud Harmouch

Genius 5255 points

Hi Mahmoud-san,

Thank you for your support.

I deeply recognized the need for a pull-up resistor in open-load detection.

Is there anything to worry about attaching a pull-up resistor?

For example, the system consumption current increases, etc.

In addition to the detection accuracy of open load please tell me if there is a change point with or without pull up.

Best regards,

Tomoaki Yoshida

0 Mahmoud Harmouch over 7 years ago in reply to Tomoaki Yoshida91

TI__Mastermind 28260 points

Hello Yoshida-san,

The pull-up helps to detect open load in off state but the supply current will increase by around 18mA.

Regards, Mahmoud

0 Mahmoud Harmouch over 7 years ago in reply to Mahmoud Harmouch

TI__Mastermind 28260 points

Correction: 18mA is a typo mistake. The supply current is much less than 18mA. I will measure it and post the right value.

0 Mahmoud Harmouch over 7 years ago in reply to Tomoaki Yoshida91

TI__Mastermind 28260 points

The pull-up resistor is in parallel to the FET and current into the resistor is very low. But by having this pull up resistor the diagnosis is enabled for pulling high the CS voltage to 6V and pull down the FAULT to 0V. This why the supply current is increased by 18mA.

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TPS4H160-Q1: Automatic retry time after open-load detection