LM4861 VIH and VIL for Shutdown input

Hi David,

Unfortunately it is not certain in this device documentation if the gate used in the shutdown control is CMOS or TTL, so I would recommend to use voltages for VIH at least 2/3*VDD and VIL up to 0.8V. In addition, it is recommended to switch between actual GND and VDD to control shutdown pin.
I will try to get specific data for this device although the people who developed this device are no longer in TI.

Best regards,
-Ivan Salazar
Texas Instruments

HI Ivan;

Please let me know when you confirm CMOS or TTL input, as the customer's VDD is +5V and he has designed with a 1.8V logic level and needs to confirm the Vih/Vil levels. 

I ordered a sample of the LM4861 and configured it per the typical audio amplifier application circuit in Figure 2 on page 2 of the datasheet.

 

The threshold of the SHUTDOWN pin input is Vdd/2. Levels above Vdd/2 will result in the amp entering Shutdown mode.  The shutdown feature turns the amplifier off when a logic high is placed on the

shutdown pin.

 

With a VDD=5V, the Shutdown goes active above 2.5V, and goes in-active below 2.5V.

With a VDD=4V, the Shutdown goes active above 2.0V, and goes in-active below 2.0V.

With a VDD=3.3V, the Shutdown goes active above 1.65V, and goes in-active below 1.65V.

With a VDD=3V, the Shutdown goes active above 1.5V, and goes in-active below 1.5V.

 

Can you confirm this is the desired operation?

Hi David,

I'm about to perform the same test as soon as I have the samples. But this is what I would expect, too.

Best regards,
-Ivan Salazar
Texas Instruments