UCC27611: UCC27611 with VDD = 5 V

Michael Levin72

Part Number: UCC27611

Tool/software:

Hi support team,

I'd like to use the UCC27611 gate driver with VDD = 5 V. The datasheet says that it can operate from 4 V, so formally everything looks OK. Nevertheless, I have some doubt, because the output voltage of the internal LDO (VREF) can be in the range 4.75 to 5.15 V. If VDD = 4.5 V, the LDO will definitely be off, and I suppose VREF will just track the VDD voltage. If VDD = 12 V, VREF must be in the specified range.

Please answer the following questions:

1. What is the state of the LDO when VDD = 5 V?

2. Is there a way to make sure the LDO is in a definite state (not turning on and off occasionally) with VDD = 5 V?

2. Can VDD and VREF pins be connected together and supplied from the same 5 V source?

2 months ago

0 Rubas Khalid 2 months ago

TI__Expert 5635 points

Hi Michael,

1. The dropout voltage for LDOs are typically 0.3V-1V more than its regulated output. Below is a generic LDO output vs. input voltage, showcasing the different regions:

Unfortunately, the dropout voltage for the LDO in the UCC27611 is not in the datasheet, so I would recommend to have VDD be at least 6V to guarantee the LDO to be fully active. I simulated the UCC27611 at VDD = 5V, and I got VREF at 4.95V:

2. The UCC27611 has a typical UVLO of 3.8V, so as long as the VDD is in the recommended range, the LDO powering VREF should be active. At VDD = 5V, the device should be powered as normal.

3. VREF has an absolute max voltage of 6V. You can tie VDD and VREF together, but make sure the voltage does not exceed 6V.

Thanks,
Rubas

0 Michael Levin72 2 months ago in reply to Rubas Khalid

Prodigy 230 points

Hi Rubas, thank you very much! What is the software used for the simulation?

Best regards,

MIchael

0 Rubas Khalid 2 months ago in reply to Michael Levin72

TI__Expert 5635 points

Hi Michael,

I used PSpice for TI to simulate. You can find it here: https://www.ti.com/tool/PSPICE-FOR-TI

Thanks,
Rubas

0 Michael Levin72 2 months ago in reply to Rubas Khalid

Prodigy 230 points

Hi Rubas, thank you very much again!

Best regards,

Michael

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UCC27611: UCC27611 with VDD = 5 V