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OPA340: OPA340MDBVTEP

VISHAL THOMAS
Prodigy 10 points
Part Number: OPA340
Other Parts Discussed in Thread: TINA-TI

Hi TI Expert Team,

I am using OPA340 in my design. I have a case where OPA340 need to sink small current in uA. But I couldnt find in Datasheet how much is Sink current capability of OPA340 output. In my Case, the Output Voltage is 5V with series resistor of 5K.

Kindly Advise.

  • 0
    Guru 140200 points

    Hi Vishal,

    from your description it is not clear what you are planning to do. Please give more details and show a schematic.

    By the way, "sinking" means that a current is flowing into the output of OPAmp. Figure 15 of datasheet shows how the output of OPA340 with its output voltage fully driven to the rails will behave when sourcing or sinking current. You can easily see that the OPA340 can not only source but also sink currents of dozens of mA.

    Kai

  • 0
    TI__Guru 64430 points

    Adding to Kai reply, if the 5k load is connected between Vout and ground,  in a single supply application Vout is always above ground and thus it is NOT possible to sink ANY load current- see below.  With Vout at 5V and 5k load grounded, the required souring current would be Iout=5V/5k =1mA -well within minimum +/-20mA capability of OPA340 at ANY specified temperature

    On the other hand, with 5k load connected to Vcc, the output would be required to sink max 1mA for Vout=~5V, which is well within capability of OPA340.

    The actual OPA340 output drive sinking/sourcing capability is shown in Fig 15 for different temperatures. At 25C the short-circuit current is +/-50mA-see below.

  • 0 in reply to kai klaas69
    Prodigy 10 points

    Thanks for the response.  I am sorry if the given datas wasnt clear about the case.

    I am trying to find the value of current limit resistor R19 needed for the Opamp U2 for a pulse of 5V.

    Thank you for the mentioning the Figure 15 where it shows Sink and Source limits are same.

  • 0 in reply to VISHAL THOMAS
    TI__Guru 64430 points

    Vishal,

    You may easily simulate the sinking/sourcing performance of the OPA340 showing output current of +637uA/-342uA - see below. Btw, there is no need to use  in your circuit C2 of 10F cap - see below.

    Below I have attached Tina-TI schematic for your own simulations.

    Vishal OPA340 transient.TSC

  • 0 in reply to Marek Lis
    Prodigy 10 points

    Thanks for the response. 

    This is very helpful and I will make the changes accordingily.

  • 0 in reply to VISHAL THOMAS
    TI__Guru 64430 points

    No problem. Good luck!