Need to verify schematic for TPS65721

Sangeet Dandona

Other Parts Discussed in Thread: TPS65721

Hello,

I've attached a image of the current PMU setupusing the tps65721 to generate 3.3V on the DCDC converter and then produce 1.8V on the LDO and I just wanted to verify that my design looks ok. In addition, there is a mode pin that I currently left floating which determines whether the regulator is in PWM mode or PFM mode. Is it ok to leave that floating or should I tie it to gnd/VDD?

Thanks,

Sangeet

over 8 years ago

0 Michael Green over 8 years ago

TI__Genius 16870 points

HI,

You must terminate the MODE pin. Either connect it to GND or high, do not float.

Are you using it with a battery? Grounding HOLD pins will result in the corresponding DCDC or LDO to shutdown immediately after AC is removed.

0 Sangeet Dandona over 8 years ago in reply to Michael Green

Prodigy 110 points

Hi Mike,

Yeah, I am going to be using it with a battery. The current charging scheme is to charge with 5V from USB and then once that is complete, swtich to using a lipo battery. Should I just have the HOLD pins connected to VSYS then? Would it be alright to email you my current schematic just to see if everything is ok in terms of the PMU usage?

Thanks for your help.

Sangeet

0 Michael Green over 8 years ago in reply to Sangeet Dandona

TI__Genius 16870 points

You can email me anything you want. msgreen@ti.com.

To answer the question on how to connect the HOLD pins, I need to ask how you wish to operate the DCDC and LDO.? Do you want them to always be ON?

0 Sangeet Dandona over 8 years ago in reply to Michael Green

Prodigy 110 points

Hi Mike,

Yes, I would always like to have the DCDC and LDO on.

Thanks,

Sangeet

0 Sangeet Dandona over 8 years ago in reply to Sangeet Dandona

Prodigy 110 points

Hi Michael,

I updated the design so that the MODE pin is tied low to keep it in PWM/PFM mode and the HOLD pins are now tied high to VSYS to keep the dcdc/LDO on after PB_IN returns high. Is this the correct approach for keeping the PMIC on?

Thanks,

Sangeet