Bidirectional buck boost dc dc converter for charging and discharging the batteries

Current control is done with a current output DAC feeding the desired IMON pin on the 8708. The 8708-1 will duplicate so actual current will be 2X.

See 8708-1 datasheet and DC2719A demoboard.

The above control design with Microcontroller. Can it possible with DC2719A

External control of current and voltage on the DC2719A can be done. Using PWM to control the voltage and current can be done but must be filtered well so the output has very little ripple. Recommended method for voltage control is to feed the FB pin by a voltage output DAC through a resistor. Recommended current control is with a current output DAC to the IMON pin. Of course a micro can control the DACs.

External control of current and voltage on the DC2719A can be done. Using PWM to control the voltage and current can be done but must be filtered well so the output has very little ripple. Recommended method for voltage control is to feed the FB pin by a voltage output DAC through a resistor. Recommended current control is with a current output DAC to the IMON pin. Of course a micro can control the DACs.

I understand what you said but can you please explain me how can I acheive this. I dnt have much experience in electronics.

Micro controls DAC (digital to analog converter), DAC output to FB pin or IMON pin. A micro needs to support the serial communication of the DAC selected. Select a voltage output DAC to feed the LT8708 FB pin through a resistor to control output voltage. Select a current output DAC to feed the desired IMON pin on the 8708 to control current.

If you prefer to use a PWM output then an RC filter or op-amp integrator will be needed to remove the ripple.

Hi CharlieADI I have a few follow up questions to your response above:

1) Why is a voltage output DAC recommended for the FB for voltage regulation? Should it instead be the LTC7106 which is a current output DAC?

2) I want to have 2 DACs - one for dynamic voltage control and one for dynamic current control. Do you control if you're in CC or CV mode by adjusting the one you want to control to it's desired value and then increase the value of the other variable to ensure that it is not the limiting variable in the control. i.e. I want to be in CC mode, so set current to what I want and then set voltage setpoint plenty high to sure it never limits?

3) My application is NiCd batteries. I want to build generic hardware capable of a wide range of voltage and current and then use a microcontroller to adjust the DACs. Each customer or battery would get its own charging profile and this would define a unique part number based on software. I am guessing that 250W is a practical limit for each phase of the buck-boost. For the batteries I want to charge, I would need 5 to 6 phases. Will one LT8708 work well with 5 LT8708-1s. And what is the current output accuracy that I can achieve?

Thanks,

Brian