BQ24075: Pin settings

Hi Zeming,

Zeming Kong said:

1. It is used for a max. 630mA battery, so ISET = 630mA, ILIM = system consumption current + 630mA?

Yes, this is correct. The ILIM setting should be programmed for an input current that can handle at least the programmed fast charge current and the system load. 

Zeming Kong said:

2. Can we connect TS to the battery NTC pin directly? this battery has a 10k internal NTC resistor.

Yes, if the battery already has an NTC resistor, the TS pin can be directly connected to the NTC. The TS thresholds will depend on the beta value of the resistor. You can use Linear Charger NTC Calculator to verify the temperature thresholds.

Zeming Kong said:

3. How to set the TMR? Will the default settings be enough?

The TMR pin is to configure the safety timers (pre-charge and fast charge) with a resistor.. The default setting is 5 hours for the fast charge timer and 30 minutes for the pre-charge timer. Whether this is enough will depend on the battery capacity

Zeming Kong said:

If we don't need SYSOFF and CE pins, can we connect them to GND directly?

Yes, if no control is needed, this can be connected to ground directly.

Best Regards,

Anthony Pham

Hi Zeming,

In the functional block diagram, we show a Q1 FET for functionality. In actuality, it is a pair of back to back FETS to prevent any current and voltage going back to the IN. If IN is not present and the system is powered by the BAT, there will be 0 V present on the IN pin.