# Dual-supply for MAX4310

I'm reading the datasheet of MAX4310:

https://datasheets.maximintegrated.com/en/ds/MAX4310-MAX4315.pdf

and I'm not sure how to configure the supply rails. The video input signals are AC coupled, hence they span below the GND rail.

I don't want to put a common mode voltage because I have very small free space on the board. At page 11 I read:

Vcc: Positive power supply

Vee: Negative Power Supply. Ground for single-supply operation.

I wonder if I can generate a -3V rail with an LTC1983-3 (http://cds.linear.com/docs/en/datasheet/1983fc.pdf) and then power the MAX4310 using a +5V on Vcc and -3V on Vee.

It hasn't a ground pin, though... how it can sense "where" is the 0V rail?

## 1 Answer

The device is actually single rail but you can drive it with +5/-3V if you so wish. However, if you do, you will need to translate your control signals to also be to those levels.

If your signals are not DC or low frequency, you will probably be better off, less components, with a normal grounded supply and biasing the inputs to half rail and then AC coupling the output again.

• Well, using a LTC1983-5 I can supply it with a ±5V: in this way the output should be centered around 0V as the input is. About control signals: I think you're talking about A0 that should switch between Vcc and Vee. – Mark May 17 '17 at 19:42
• The problem with biasing is if I need to add a DC to a signal that go below 0V I need a negative rail anyway, to drive the op-amps. Don't I? – Mark May 17 '17 at 19:43
• @Mark you say the inputs are AC coupled but do not explain that well in the question. If there is a DC offset on the signal, yes you need to use two rails. But like I say, if you do that you also need to make your control logic signals go to those rails too. – Trevor_G May 17 '17 at 20:06
• I'm sorry. I was saying that my signal are video signals: hence they are 1Vpp. Being AC coupled they swing between -500mV and +500 mV. I've got your point, thank you. – Mark May 17 '17 at 20:10