TPS50601-SP: Questions about EN-pin & PWRGD-pin

Noriyuki Takahashi

Part Number: TPS50601-SP
Other Parts Discussed in Thread: LM139-SP,

Hi team

Customer has several questions about EN-pin.

1. What is the state of EN-pin during VIN = PVIN = 0V?

2. Can the EN pin be controlled by connecting the outputs of the logic IC if the threshold voltage: 1.13 to 1.18V and current: 3.2uA are satisfied?
Or do they need to use open-drain or open-collector output logic(like LM139-SP) to interface with the pin?

3. How should they deal with PWRGD pin when the pin is unused?

Regards,

Noriyuki Takahashi

over 3 years ago

0 Christian Yots over 3 years ago

TI__Genius 14540 points

Hi,

1) The EN pin has internal pullup so if left floating the device will become active. However, this pullup is referenced to VIN so with VIN=0 the device remains disbled.

2) Yes, EN pin can be controlled by a logic IC as long as the input tolerances are respected as you mentioned. Also, the EN pin can be tied to a resistor divider from the PVIN input so that the EN functionality is restrained to a limited range. The EVM uses this resistor divider limit the range of operation of the device versus PVIN.

3) The PWRGD pin can be left floating if unused. However, as this pin connect to the open drain of a transistor, all testing and characterization was done with a pullu resistor in order to complete the circuit.

Thanks

Christian

0 Noriyuki Takahashi over 3 years ago in reply to Christian Yots

TI__Genius 10010 points

Christian,

Thanks,

2) They don't want to use a logic IC to control EN-pin, because it increase the cost and it's difficult to find the good one for this. So, is it OK to connect GPIO-pin directly to EN-pin?

They also have one more question.

What is the state of PWRGD-pin during VIN = PVIN = 0V?

Regards,

Noriyuki Takahashi

0 Sarah Koch over 3 years ago in reply to Noriyuki Takahashi

TI__Expert 9000 points

Hi Noriyuki,

I will ask Christian to comment on your follow-up questions.

Regards,

Sarah

0 Christian Yots over 3 years ago in reply to Sarah Koch

TI__Genius 14540 points

Hi Again,

Yes, EN pin can be controlled by GPIO pin. Note there is an internal pullup on this pin internal to the IC.

PWRGD pin is held low with VIN=PVIN=0V as output will be detected as outside the regulation window.

Thanks

Christian

0 Noriyuki Takahashi over 3 years ago in reply to Christian Yots

TI__Genius 10010 points

Christian,

Thanks.

Please let me ask one more question.

They want to use 2pcs TPS50601-SP. They want to turn off the one by connecting PWRGD and EN when the input of the other is turned to 0V as the attached.TPS50601 SP.pptx

Could you confirm whether this work?

Please also let me confirm below.

"PWRGD pin is held low with VIN=PVIN=0V" means PWRGD-pin is connected to GND?

Regards,

Noriyuki Takahashi

0 Christian Yots over 3 years ago in reply to Noriyuki Takahashi

TI__Genius 14540 points

Hi,

PWRGD pin is an open drain so it will require a pullup resistor in order to complete the circuit. But yes, the output pin of PWRGD should be able to control the input pin EN on the DUT B as shown.

Thanks

Christian

0 Noriyuki Takahashi over 3 years ago in reply to Christian Yots

TI__Genius 10010 points

Christian,

Thanks.

What is the leakage current of PWRGD-pin during VIN=PVIN=0V?

I can see it is 30nA typ during VIN=PVIN=5V according to the datasheet. I am not sure what it is during VIN=PVIN=0V. They need it to calculate the value of the pull-up reister.

Regards,

Noriyuki Takahashi

0 Sarah Koch over 3 years ago in reply to Noriyuki Takahashi

TI__Expert 9000 points

Hi Noriyuki,

Since VIN needs to be at least 1V for PWRGD to be in a defined state, I'm not sure this is information is given in the datasheet. I will ask Christian if he can provide additional details or information.

Thanks,

Sarah

0 Christian Yots over 3 years ago in reply to Sarah Koch

TI__Genius 14540 points

Hi,

This device was tested and characterized with a 2mA bias current in the PWRGD circuitry. Therefore, we recommend a pullup resistor that yields ~2mA when this pin is pulled low. For a 5V supply, Rpullup would be ~2.5kohms.

Thanks

Christian

0 Noriyuki Takahashi over 3 years ago in reply to Christian Yots

TI__Genius 10010 points

Christian

Sorry for confusing.

As we discussed, customer understands that PWRGD pin is held low with VIN=PVIN=0V. So customer wants to understand how much current can flow to PWRGD-pin when PWRGD pin is held low with VIN=PVIN=0V. Could you please again this?

Regards,

Noriyuki Takahashi

+1 Christian Yots over 3 years ago in reply to Noriyuki Takahashi

TI__Genius 14540 points

Hi,

Sorry for the confusion. As Sarah mentions, the PWRGD circuitry only functions when VIN>1V. Therefore, with PVIN=VIN=0V the PWRGD pin is not functioning and the PWRGD output pin will be pulled to whatever bias is provided externally. If the pullup resistor on the PWRGD pin is tied to PVIN, as is the case on the EVM, then this pin will be pulled to the PVIN bias which is 0V. In this case, the current will be zero or near zero. We have no measured data in this state.

Thanks

Christian

0 Noriyuki Takahashi over 3 years ago in reply to Christian Yots

TI__Genius 10010 points

Christian, Sarah

Thanks!

Regards,

Noriyuki Takahashi

0 Christian Yots over 3 years ago in reply to Noriyuki Takahashi

TI__Genius 14540 points

You are welcome-anytime.

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TPS50601-SP: Questions about EN-pin & PWRGD-pin