Author Topic: What DCDC VRegs have a constant current limit feature? Its hard to search for it  (Read 720 times)

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Offline PsiTopic starter

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I'm looking for a little monolithic DCDC VReg chip but I'm having trouble finding an all-in-one IC solution that fits my requirements.
Anyone know a chip that has the following specs?

- My main requirement, (the one causing issues), is a built-in constant current regulation feature.
I want it do CC mode at around 3A with the output going down to a few volts in CC mode.
I have found some chips that have CC mode, but they sense current in the ground line. For my application input and output ground must be common.
- Built-in switching mosfet
- Input 12/24v system, so needs to be spec'ed to run up to 32V
- Output regulated to 15V (if Vin high enough)
- Step-down (or could be step-up/down)
- Ideally automotive rated spec
- Price per chip can be high-ish, if needed. $8 each at 100pcs is not out of the question.

Any recommendations welcome.
« Last Edit: November 02, 2020, 10:58:18 am by Psi »
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Offline daqq

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Could this work?

https://www.analog.com/media/en/technical-documentation/data-sheets/3477fd.pdf

edit: See page 14 for higher voltage operation.
« Last Edit: November 02, 2020, 10:51:43 am by daqq »
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Offline PsiTopic starter

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Could this work?

https://www.analog.com/media/en/technical-documentation/data-sheets/3477fd.pdf

edit: See page 14 for higher voltage operation.

Sadly the circuit on page 14 that allows higher voltage operation removes the common ground between input and output.
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Offline tom66

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You could implement this function by driving the FB line of many conventional DC-DC converters with an external op-amp.  That op-amp could use a high side current sensor (e.g. Zetex ZXCT10xx) to monitor output current.  If you use a diode to OR your feedback signal, then you could have CV/CC operation.

I appreciate this is more complex than an off-the-shelf solution but it may end up giving you the most availability.
 

Offline PsiTopic starter

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You could implement this function by driving the FB line of many conventional DC-DC converters with an external op-amp.  That op-amp could use a high side current sensor (e.g. Zetex ZXCT10xx) to monitor output current.  If you use a diode to OR your feedback signal, then you could have CV/CC operation.

I appreciate this is more complex than an off-the-shelf solution but it may end up giving you the most availability.

yes, this is my fallback option.
I just really want something that's ready to go and am willing to pay a bit more for it.

For this project being able to take the example schematic from the datasheet and know it will work first time will be a big time saver. It will require less testing and validation.
« Last Edit: November 02, 2020, 11:07:45 am by Psi »
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