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TPS63020: Does LDO at the o/p of TPS63020 necessary for powering the RF Modules

Raghavendra Hasigal
Prodigy 105 points
Part Number: TPS63020

Hi There,

During searching for the Buck-Boost for the battery operating design, i have came across TPS63020 chip.

In my design i need to Power nRF BLE module and LORA module with 3.3V. Do i need to add the LDO at the TPS63020 for voltage to be stable ?

Thanks

Raghavendra

  • 0
    TI__Expert 7925 points

    Hi Raghavendra,

    Normally, I would say you don't need an LDO, but you should check the power supply requirements for your RF modules. If you give us the operating conditions (input/output voltage and the output current) we can give you typical output ripple.

    Best regards,
    Milos

  • 0 in reply to Milos
    Prodigy 105 points

    Hi Milos,

                   Thanks for looking into it!  Please have a look on the below mentioned operating conditions.

    Input : 2.5V - 4.2V

    Input Current - 4200mAh Battery

    Output Voltage - 3.3V

    Output Current - 1A ( Normally RF devices consumes 200 - 300 mA, Motor draws some 300 - 400 mA [ yes motor works on 3.3V ]).

    Thanks

    Raghavendra

  • 0 in reply to Raghavendra Hasigal
    TI__Guru 65370 points

    Hello Raghavendra,

    How much ripple is allowed on the RF device? Do you have a maximum limit for the output capacitance? In PWM operation, the ripple can be reduced by adding capacitance.

    Is it possible that the motor starts while the RF is active? Then checking the load transient response would be necessary as well.

  • 0 in reply to Raghavendra Hasigal
    TI__Expert 7925 points

    Hi Raghavendra,

    Under those conditions you can expect around 5 mVpp ripple in PWM mode, and at most 90 mVpp outout voltage ripple in PFM (power save) mode. This is valid for our TPS63020EVM-487, and the output capacitors we have there. If you are using power-save mode, for loads above 150 mA the device will automatically switch to PWM mode, therefore whenever your RF device or the motor are on, the ripple will be minimal.

    As for the load transients, if you turn on/off your loads individually, you can expect the output voltage undershoots/overshoots to be within 100 mV.

    Best regards,
    Milos