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Boost Circuit Design - ADP1621 suitable?

Question asked by GasGas on May 5, 2014
Latest reply on May 6, 2014 by kevintompsett

Good evening.

 

I'm searching for an IC that is able to:

  • provide an output of 6, 9 or 12V (adjustable) @ 1.5A at a maximum duty cycle of 100mS on/5sec off from a high current LIFePO4 cell (2.0 to 3.6VDC).
  • to be put into a standby mode,
  • draws minimal (uA) current in standby.

 

I had hoped the ADP1614 would do the job as it doesn't use many external components but alas, the ADP1621 Boost Designer says no, it can't generate the required current at 12V. The ADP1621 seems as though it may do the job however I'm having trouble determining which components are actually required to make the thing work using the Designer. The circuit diagram in the Designer has a bunch of extra components compared to the sample circuits on the spec sheet so I don't know which components in the BOM are required. For instance there are 3 MOSFETs connected to the gate and two of them have part numbers against them in the BOM - are both of these required? Also it seems a sense resistor is required but I thought the 1621 could operate without one?

 

Essentially I'm aiming to design the simplest circuit possible that can meet the above requirements. I had planned to base the design on figure 40 of the ADP1621 spec and use FETs in series with resistors in parallel with RF2 or a digipot in place of RF2 to control the output voltage.

 

Any help would be greatly appreciated. Thanks in advance.

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