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LTC4006 - Dynamically adjust charging current?

Question asked by PWise on Mar 30, 2018
Latest reply on Apr 2, 2018 by Zack

I'm trying to adapt an existing product design that uses an LTC4006-2, to allow the charge current to be adjusted (downward) dynamically via a control signal from a local MCU.  If I had the opportunity, I would redesign the whole thing and use something like an LTC4100, but I don't have than option right now.

 

The datasheet spells out how to set the current and it is pretty straight forward, but it's intended to be a fixed setting.  My circuit is currently configured for 3A.  However, I have the need to sometimes force the current to something less (say 1.5A).  I'm not necessarily talking about slewing the the charge rate, rather one, maybe two additional settings that are something lower than the 3A.

 

One idea I had is to apply a PWM to the NTC pin.  I don't use that signal for an actual thermistor connection from the battery but I do have it tied to my MCU in such a way that I can suspend the charge state when I want to.  My other thought was to perhaps control a switch that adds a small offset to the CSP pin.

 

Looking for thoughts/ideas.

 

Thanks,

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