current sense

[electros6]

Hi guys ,
           I am working on a project where I want to implement high side current sense on a 48V dc supply rail. Please guide me

[TerminalJack505]

I'd use one of the ICs dedicated for this.  TI's INA169, for example.

[tszaboo]

Self advertising:
http://nandblog.com/current-shunt-monitors/
I suggest the INA19x series.

[Andreas]

LTC6101 or LTC6101HV

With best regards

Andreas

[tree]

MAX4372.

I used that to build a battery monitor when I was an intern at NASA. One of the high ranking EEs advised that we use that chip because it's a legacy component (i.e. flew successfully on previous missions)

[tszaboo]

MAX4372.

... is a 28V part, which will fry with 48V.

[tree]

MAX4372.

... is a 28V part, which will fry with 48V.

I thought he meant he has to monitor current on a 48V rail. (i.e. not necessarily running the chip on 48V)

EDIT: Never mind. common mode is limited to 28V.

[SeanB]

http://www.analog.com/en/circuits-from-the-lab/CN0218/vc.html

Just released as a current monitor with a 500V CMMR range.....

Even has a video on the channel.

[nctnico]

This is a very expensive solution. Its better to use a hall sensor from Allegro if you need high voltage isolation. The Adum5xxx parts look nice though. I've used one to isolate a circuit to meaure the mains voltage.

[fcb]

To some extent it will depend on what bandwidth, accuracy, current & calibration you want.

The gold standard would of-course be a differential amplifier across a nice little low-tempco 4 terminal shunt. Perhaps you can afford a little current drain from both sides, in which case you could use potential dividers to make that 48v a bit easier to interface to.

However at 48v (4 lead-acids, telecoms 36-72v, mic phantom powering, PoE, PSU, traction...?) we would need to know a little bit more to really advise.

*NOTE/RANT* - when I started out in electronics MAXIM used to send out these little blue & white pamphlet/magazines (perhaps they still do?).  I often used to design using stuff from them - same goes from National/TI/ST, even when the BOM wasn't an issue, the sourcing of these parts was always a headache.  Nowadays I'm loathed to change from designing in LM358/NE5532/TL072/LM339/ULN2803A, etc unless absolutely necessary.

**THAT SAID** - I love the Allegro ACS parts that nctnico talks of.  Just finished a design job with them in - real pleasure to do.