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LP87702-Q1: LP87702 - Input circuit: One or Two?

Kevin Kreger
Expert 1020 points
Part Number: LP87702-Q1
Other Parts Discussed in Thread: LP87702, BQ24075T

The datasheet for the LP87702-Q1 Evaluation Board Schematic (below) shows two input circuits for VIN_B0 and VIN_B1 even though the input voltage VIN is the same for both.

However, the data sheet for the part shows a single circuit connected to both VIN_B0 and VIN_B1. We would like to use a single circuit to reduce part count,

but we have no idea why the EVM and Data Sheet have conflicting circuits. 

  • 0
    TI__Intellectual 950 points
    Hi Kevin,

    Typical application figure 81. in the datasheet is simplified and thats why it looks a bit different. LP87702 will need independent input capacitors close to VIN_Bx pin as evaluation module shows. We also recommended to use 10uF input capacitor for BOOST input pin as well, even it is not shown in the simplified datasheet figure, but will found from the evaluation module schematics.

    Direct answer to question "one or two" is two

    Tuomo
  • 0 in reply to Tuomo Alatalo
    Expert 1020 points

    Hi Tuomo,

    Thanks for the prompt and very helpful reply. We have reviewed the circuit to ensure all have 10uF as shown.

    I understand the simplification on the datasheet now as well. Note that we also are not having the PI filter

    to the left of the 10uF caps as we are battery operated and in close communication with the output of the

    BQ24075T as shown on the schematic below. If you think this is not advisable then please reply

    Otherwise, I think if you don't have anything to add then we can consider this solved.

    Best,

    Kevin

  • 0 in reply to Kevin Kreger
    TI__Intellectual 950 points

    Hi Kevin,

    You should be good with the 10uF input capacitors as it is our minimum recommendation in datasheet

    Tuomo