OPA549: some questions

Hello Sho,

Please see the answers I have provided.

1.Is the E/S pin input and output pin? If yes, please tel me the condition of input and output.

The E/S pin has two different functions. It can be used as an enable/shutdown pin, an input function, or as a thermal shutdown flag, an output function. The enable shutdown function is explained on datasheet page 9, the ENABLE/STATUS (E/S) PIN section. The thermal flag function is explained on page 10, Thermal Shutdown Status section.

2.As conditions for shutdown, "CURRENT LIMIT" and "THERMAL SHUTDOWN "and" E / S pin to Low Level "?

The voltage levels associated with E/S input function, or Thermal Shutdown Status Output function, are provided in the Electrical Characteristics table on page 3, under the OUTPUT ENABLE/STATUS (E/S) PIN title.

3.Please tell me the condition to re-enable about "current limit".

The current limit is a hard limit that is set by the R_CL resistance value explained in the Resistor-Controlled Current Limit section of the datasheet, on page 9. If the output current remains lower than the current limit setting, the output will not go into the current limit mode. If exceeded, the output current will be limited at the set value.

4.Now E/S pi n is open, Ref pin is 0V, Vss=±5V, Vout=±2.5V, Iout=2A, Ilim pin =22k ohm and 0.01uF.
I measured the E/S pin. I think E/S=2.4~3.5V,but the voltage is 2V.
Please tell me the E/S voltage value.

The (Ref) + 2.4 V is applicable to the stated condition where Vs = +/-30 V. The E/S pin will pull up to that voltage level as a minimum, under that supply condition. In your case, the supply is much lower, +/-5 V. We do not specify the level it will pull up to under that supply condition, but +2 V is a reasonable level. For best noise immunity it is better to connect the E/S pin to a level of (Ref) + 2.4 V, or higher.

Regards, Thomas

Precision Amplifiers Applications Engineering