AD8591_Single-supply operation and shutdown fuction.

Hi Josh,

1. Can I know what application are you using AD8591 and why you want to use V+ : 0V, V- : -5V?

It is possible to use the supplies that you mentioned as long as the difference between the V+ and V- is from 2.5V to 6V.

2. AD8591 is a CMOS amplifier, the input for the Shutdown function is a CMOS input and it cannot be left floating.

In the simplified schematic on page11, the Shutdown inverter is connected to the input of PMOS which turns ON for a LOW input.This means that to get a LOW input at the gate of the PMOS, the Shutdown input should be HIGH.

Therefore, it is best to tie LOW the Shutdown pin preferably w/ a resistor 10k to 1 Meg to ground when Shutdown is not used.

Arthur

Hi Arthur,

1. AD8591 will be used for gate bias circuit of GaN TR. Gate bias of GaN TR needs negative voltage.

   Shutdown fuction will be applied for GaN TR on/off.

2. If supply voltage is V+:0V, V-: -5V and shutdown fuction is not used, How do we handle Shutdown Pin? high(0V:GND) or low(-5V)?

we are looking forward to your advice.

thanks,

Best regards,

Josh  

Hi Josh,

2. Connect the shutdown pin to high(0V:GND) to disable shutdown function.