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LMH6321MR

Hi,

We are using a LMH6321MR voltage follower at the output of a DAC. The voltage at the buffer's input remains constant with or without any load. When a load of 2K Ohm is connected to the output of the buffer (pin 6) and removed there is a variation of 21mV at the output. For eg. the voltage is 10.0260V but when the load is removed it falls to 10.0050V (The voltage remains at 10.0399V at the input pin 3 of LMH632MR with or without load). The EF and CL pins are pulled up to +15 and +5 respectively.

This is causing a problem because the specification says the variation of voltage with or without load should not be more than 1.2mV. Is there any solution for this problem or any other component that can match the requirement.

Please suggest any tweaks or any other component.

 

  • Hello Sathya,

    Can you please provide a schematic?

    Specifically: What value pullup resistors are you using on EF and CL?

    Are you running single or split supply? What is the GND pin connected to? What is V- connected to?

    Do you have a series output resistor? Do you have a 100 ohm resistor on the input? (As mentioned in the Apps section).

    Have you looked for high-frequency oscillations with a scope? Is the buffer getting overly warm?

    Your layout should follow proper high-speed layout precautions, as the buffer has both high currents and high slew-rates, which can oscillate due to improper bypassing or layout. Good ground planes are a must.

    Regards,

  • Hello Paul,

    Here is the schematic.Please have a look. The input is DC ~= 10V. There is no heating of IC observed.

    The voltage does not remain constant at Analog_Voltage_OUT3 when a load of 2K Ohm is connected and removed.  Will it cause a problem if 10K ohm is connected at the input as shown above?