ADR425 equiv with sink capabilities.

Sep 19, 2006 3 Replies
F

In a attempt to be clever I used this ref for making a floating negative ref voltage, without checking further than some datasheet internal drawing showing the output driver as an opamp.



Yes, I should have known better, but now I've something like:



.---------------. V+ -----|Vcc Vout |--------. | | | | | === | | GND | | | | | 0V | '---------------' | | +---------------> -Vref | .-. | | | | '-' | V-


with a ref. that can't sink the output current, so it doesn't work.



Anyone knowing a pin compatible substitution for the ADR425 (5V-MSOP8) able to sink current. This will avoid me a new PCB run.



Thanks, Fred.
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J

Similar to the data sheet Figure 47:

.---------------. V+ -----|Vcc Vout |-----. .-------. | | | | | | | --------- === | | \\ - + / GND | | \\ / | | \\ / | 0V | \\ / '---------------' | | | | | +---------------+-----> OUT

Of course it takes a really good OpAmp to maintain the accuracy :-(

...Jim Thompson

| James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
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F

Jim Thompson a écrit :

Indeed, but I was trying to avoid that :-)

Thanks, Fred.
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T

In article , Fred Bartoli

Could you hack an ADR550 in there, as a two-terminal shunt reference between GND and -Vref?

Tony Williams.
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