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LM359 for non-inverting Amplifier

Nat Wong
Genius 3070 points
Other Parts Discussed in Thread: LM359

Dear Sirs

I use LM359  for non-inverting Amplifier using for the following circuit (figure 1). (power supply Vcc is 5V)

1.What is pin ISET(OUT),  ISET(IN) and COMPA  function?

2.(figure 2) Ch1 is Vin, Why Vout (ch2) have 5V bias voltage?  Thanks

fig1

fig2

BRS

Nat

  • 0
    TI__Genius 13935 points
    Hello Nat,

    I think the answers to your questions are on pages 8, 9 and 10 of the datasheet.
    The LM359 has additional functions compared to a standard op amp. The extra pins you reference are related to programmable supply current.

    In the schematic you show there is no DC path for the non-inverting input bias current. That is probably what is causing the output voltage to have the 5V bias. The datasheet, on page 9 shows some options for setting the input bias currents.

    Another option would be to use two resistors on the non inverting input to bias it's DC value to one that works for your application (2.5V would be a good start).

    Regards,
    Loren