PMP9766: Cell balancing design if change VIN (Vmain) to 5V

Ken Huang

Prodigy 30 points

Part Number: PMP9766
Other Parts Discussed in Thread: LP2998

Hi Sir,

If adopt PMP9766 module and change VIN (Vmain) to 5V and Vout (Vsys) to close 5V.

Do we need to change the design of cell balancing operation (LP2998 in EVM board)?

Thanks!

over 4 years ago

0 Bjoern Goerner over 4 years ago

TI__Intellectual 1525 points

Hello Ken,

as shown in the LP2998 functional block diagram (LP2998 Datasheet, page 11, chapter 8.2) the device regulates the Voltage at the VTT pin to 1/2 of the voltage applied to the VDDQ pin. Therefore, if you change Vin to 5V, VTT will be regulated to 2.5V and the capacitors will be perfectly balanced without any additional changes.

Best regards,
Björn

0 Ken Huang over 4 years ago in reply to Bjoern Goerner

Prodigy 30 points

Hi Sir,

If we choose the supercap stack up module and which is already including cell balancing mechanism in it.

Could we bypass and no need to design the LP2998 cell balancing circuit on our board?

0 Bjoern Goerner over 4 years ago in reply to Ken Huang

TI__Intellectual 1525 points

Hello Ken,

yes, as long as the capacitor stack has internal balancing which can keep up with the applied charging current, you do not need the LP2998 for balancing.

Best regards,

Björn

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PMP9766: Cell balancing design if change VIN (Vmain) to 5V