MP2639A IB pin - Maximum RIB value / compliance voltage?

Battery Management
1

Hello,

I’m designing a battery charger around the MP2639A and I would like to use the IB (battery current monitor) output together with an MCU ADC.

According to the datasheet:

  • The IB pin is a current output proportional to the battery current.

  • The output voltage is generated by an external resistor RIB​ connected from IB to GND.

  • Equation (1) gives:

VIB = IB * RIB

The reference design uses RIB = 40.2 kΩ, and the Electrical Characteristics specify:

  • IB voltage @ 1 A charge: typ. 0.38 V

  • IB voltage @ 1 A discharge: typ. 0.42 V

However, I cannot find any specification for:

  • Maximum recommended RIB value.

  • Maximum output compliance voltage of the IB current source.

  • Maximum output current or allowable load on the IB pin.

  • Any limitation on the output voltage before the current source saturates.

I would like to increase the ADC input range by using a larger resistor (for example 100 kΩ, 220 kΩ, or even higher), but I don’t know whether the IB output remains linear over that voltage range.

Questions:

  1. What is the maximum recommended value of RIB?

  2. What is the compliance voltage (maximum output voltage) of the IB current source?

  3. Does the IB output remain accurate with larger resistors, or is it only characterized around the 40.2 kΩ reference design?

  4. If I want approximately 2–2.5 V output at around 0.6 A charging current, is increasing RIB an acceptable approach, or should I keep RIB around 40 kΩ and instead use an external op-amp?

Any clarification from the MPS engineering team would be greatly appreciated, as this information does not appear to be specified in the datasheet.

Thank you!