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LMH6321: Is the output current shut down when the current is reached to programed current limit value by Rext?

Kazuya Nakai59
Guru 20905 points
Part Number: LMH6321

 Hello guys,

 One of my customers is considering using LMH6321 for their new products.

 They have a few questions about the device.

 Could you please give me your reply?

 Q1. Is the output current shut down when the current is reached to programed current limit value by Rext?

       Or the output current sink/source is kept. But the output current is limited to the programed value and the device gets hot when load impedance becomes low?

 Q2. The customer wants LMH6321 with single power supply (+12V only) operation. The device datasheet says "SINGLE SUPPLY OPERATION" section

        that a extra opamp needs to drive LMH6321 GND pin to take a voltage more than one VBE (∼0.7V) between V- and GND.

        In case of this, is the extra opamp sink current drivability needed more than programed current limit value?

 Your reply would be much appreciated.

 Best regards,

 Kazuya. 

  • 0
    TI__Expert 3620 points

    Hi Kazuya,

    The output current limiter works in conjunction with the short circuit protection. Basically the output current can be set from 10mA to 300mA, and the short circuit protection will tolerate up to 700mA dependent on temperature.  The device is designed to sustain continuous output within the programmable current limit of 300mA. The specifics are a bit complex, so I will refer to the relevant section (pages 17-18) of the datasheet:

    As for your second question, the GND pin is not a source/sink for output drive currents. It is a mid-supply reference for the V/I converter, and should only experience the input bias current and ESD protection for A1.

    Best regards,

    Sam