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Jeanius • Jul 6, 2008

Trouble using ADG436

I'm building a circuit that uses 4 ADG436 SPDT switch IC's (Analog Devices: ADG436: LC2MOS ±15 V Dual SPDT Switch :: Analog Switches :: Switches/Multiplexers), and am having trouble getting the switches to switch. I've got +5V, -5V, and ground correctly connected, an input voltage of +.8V at the D1 terminal, and a 0-5 V digital signal going into IN1. However, when I change the digital signal from 0V to 5V, the outputs (S1A and S1B) do not change.

Has anyone used this, or could someone provide some insight into using this IC?
Read the datasheets,there may be jumping problems..
Jeanius • Jul 8, 2008
I looked through the datasheet, and couldn't find anything I'd violated. I'm not an electrical engineer, so I could be overlooking something, but have troubleshooted the circuit so many times I'm baffled. What would cause jumping?
Buddy i think u shud give +/- 15V power suplly it will work
Jeanius • Jul 10, 2008
Unfortunately, I'm bound to +/- 5V due to the device I'm using (NI DAQ USB-6008), but I think I found out what was causing the problem.

I'm using a DC-DC voltage switching regulator (Data sheet: to obtain -5V. However, I had no connection at pins 1 and 2, which appear to be current drains and low battery detectors. Leaving this open allowed the -5V to discharge slowly to 0V (over the course of a few minutes) after disconnecting all power. After talking with Analog Devices tech support, I learned that providing a negative power supply with no positive power supply would certainly damage the ADG436. That's probably why it won't switch.

My new question, and perhaps I should start a new thread about this, is how I should go about setting up the LBD and LBR pins on the MAX634. My confusion arises from the value of Vlowbatt. I don't know what to set for Vlowbatt in the equation described on page 5 of the data sheet. If anyone could help figure that out, there is a large pile of kudos waiting for you!
Jeanius • Jul 11, 2008
I just got some advice saying that replacing the 1N914 diode specified in the wiring diagram on page 5 of the data sheet with a 1N4148 would provide some improvements, but I'm not sure if it'd solve my problem. Anyone have any ideas on whether or not this is a significant enough of a change?
Just do it and see for yourself,i can tell u only after i get through the datasheets!!

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