bqSWITCHER charge control

Q: bqSWITCHER charge control

I am looking at the BQ24100 and need the ability of the local processor to control the actual charger current.  I will determine required max current in the processor by monitoring other things in the system, and will need at least 50mA steps in the control (max current is 1.5A). In the past they have used programmable resistors or subsituted a voltage source driving a resistor into the equivalent of the Iset pin, but have not done so with this part. 

Are there other ways to implement charger current control?  A digital pot is too expensive.  Would a voltage driving a resistor into Iset work, or are there other cheap methods?

I was also thinking of suggesting a part such as the BQ24113, which is system-controlled. 


Q: Re: bqSWITCHER charge control

The programmable resistors or subsituted a voltage source driving a ressitor into the Iset pin should work on this part. Also, a voltage driving a resistor into Iset woks.  I think it is cheapest methods.

Even system-controlled (host control) IC still need to do same work to achieve that charge current control.

There is another option: using SMBus charger IC (bq24745 or bq24765). But the host also need support SMBus. So, this solution may cost more.