Hi.
This is to be the description of an IC I wanted to be able to use in boards operated by batteries, Li-Ion in this case. Maybe there is something ready from TI?
* 8 pins:
- 1,2: VCC and GND.
- 3,4,5,6: SPI or I2C or 1-wire serial interface.
- 7,8: connection for shunt resistor that monitors current.
* VCC and GND supplies the IC which is ultra-low power. There is an internal resistor divider which draws an ultra small current from VCC/battery, this is used to measure battery voltage.
* Shunt resistor between 1 to 10mR, differential mode current sensing. Maybe this shunt could be inside the IC.
* The MCU of the system could through the serial interface read and maybe set parameters/status/flags/values of battery voltage, current, power and energy, among others, from the IC.
* The IC could have an internal high-side transistor, to obtain other functionalities like protections against over-voltage/current/power, thus giving the possibility of eliminating the need of having those protection PCBs/modules that usually comes integrated inside the battery package/polymer. When I mentioned before about "set parameters" through the serial interface, I wanted to mean for example, that the high-side transistor could be configured to act as a protection to all the circuits that are connected to the output, while the MCU could detect faults according to the parameters that were set.
* The single PN IC could monitor only one cell, or 1 or 2 cells with automatic detection of number of cells, that would be great.
* Estimate battery charge percentage, MCU reads via serial.
* I did forgot about the temperature monitoring, but if the shunt is internal to the IC, one pin less is required so you can add this function (picture of the post).
* For the IC to make all that and still be ultra-low power its very hard, correct? The IC could be configured via the serial port by the MCU to enter in sleep/standby mode to reduce the ICC consumpion from the battery, for example in periods where the MCU of the board is in sleep mode, so that the processing/sampling rate of the IC would be reduced considerably.
* SPI possibility because there is no pull-ups which draws currents for logic level 0, otherwise if only I2C and 1-wire possibilities the IC could have only 6 pins like a SOT23-6.
-----> The shunt and the transistor could be both at low-side, no problem. If it works only for 1-cell it would be great also, because there would be many applications where the IC would fit. And the package could be bigger also, like a SOIC-8 sized, for higher current applications. 2 packages being available, one for low/medium current capability and another for higher capability.
Regards.
