OPA548

www.ti.com

SBOS070C – OCTOBER 1997 – REVISED JUNE 2015

Feature Description (continued)

8.3.2 Enable/Status (E/S) Pin

The Enable/Status pin provides two functions: forcing this pin LOW disables the output stage, or E/S can be

monitored to determine if the OPA548 is in thermal shutdown. One or both of these functions can be used on the

same device using single or dual supplies. For normal operation (output enabled), the E/S pin can be left open or

pulled HIGH (at least 2.4 V more than the negative rail). A small value capacitor connected between the E/S pin

and V– may be required for noisy applications.

8.3.3 Thermal Shutdown Status

Internal thermal shutdown circuitry shuts down the output when the die temperature reaches approximately

160°C, resetting when the die has cooled to 140°C. The E/S pin can be monitored to determine if shutdown has

occurred. During normal operation the voltage on the E/S pin is typically 3.5 V more than the negative rail. Once

shutdown has occurred, this voltage drops to approximately 350 mV more than the negative rail.

8.4 Device Functional Modes

8.4.1 Output Disable

A unique feature of the OPA548 is its output disable capability. This function not only conserves power during

idle periods (quiescent current drops to approximately 6 mA), but also allows multiplexing in low frequency (f <

20 kHz), multichannel applications. Signals greater than 20 kHz may cause leakage current to increase in

devices that are shutdown. Figure 33 shows the two OPA548s in a switched amplifier configuration. The ON/OFF

state of the two amplifiers is controlled by the voltage on the E/S pin.

To disable the output, the E/S pin is pulled LOW, no greater than 0.8 V more than the negative rail. Typically the

output is shutdown in 1

μs. Figure 23 provides an example of how to implement this function using a single

supply. Figure 24 gives a circuit for dual-supply applications. To return the output to an enabled state, the E/S pin

should be disconnected (open) or pulled to at least (V–) + 2.4 V. It should be noted that pulling the E/S pin HIGH

(output enabled) does not disable internal thermal shutdown.

Figure 23. Output Disable With a Single Supply

Figure 24. Output Disable With Dual Supplies

Copyright © 1997–2015, Texas Instruments Incorporated

Submit Documentation Feedback

13

Product Folder Links: OPA548