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[DPRG] Current Monitoring, boring and with PWM

Subject: [DPRG] Current Monitoring, boring and with PWM
From: DeltaGraph at aol.com DeltaGraph at aol.com
Date: Thu Feb 10 19:38:59 CST 2005

Ed,

For current sensing, the part I used is a INA139 (40 Volt Max)
Also INA169.  (That is starting with the Letter "I" )

High-Side Current Shunt Monitor

Sot 23-5 package is kinda tiny.
If you are not making a PC board you may want to get some of those surface 
mount to .100" SIP modules. If not that then tacking wire-wrap wire to the pins 
may work.

I used some surface mount .005 ohm shunts that I bought  from digikey.

I probably have some of the INA169s floating around.
Problem is they are so tiny that they could be almost anywhere.
I really need to get serious about organizing the tiny flea sized parts.

Check out TI.com (Burr-Brown product)
I think I bought some from digi-key, but they don't have any in stock right 
now.
Maybe TI would give you some samples.
They run about $1.50 each.

Also -

Check out LT1787 on digi-key.
$5 8-pin part from Linear Technology. (I think SOIC only ) 
Has ability to add a cap to low pass filter your input. That might come in 
handy.
That part was in stock.

Maybe if your operating voltage is low you could use a stock op-amp to the 
job, but there must be some complexities involved at measuring tiny voltage 
drops right on the top supply rail. Also don't know if you created a supply rail 
for the op-amp above your device's supply voltage  how that would work out. 
Someone has the answers.

Ron
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