LMH6321: What is default output current when VCL is left floating

One more question: Can Vprog be tied to V+ ?

V+ in my case is +2.5V

Hello Shubhangi,

  To clarify, are you wondering what the output current is when Vcl is left floating?

  For your second question, are you using single supply configuration?

Thank you,

Sima

Hi Sima,

Yes question is correct.

I am using dual supply +/-2.5V configuration.

Thanks,
Shubhangi

Hello Shubhangi,

   If Vcl is floating, the output current will be the maximum of the device: 700mA. At elevated temperatures this current will decrease. It is not recommended to operate the device at its maximum continuously and it is highly recommended to drive the pin. 

   For dual supply configuration: you may ground the GND pin and drive the CL pin (VCL or VPROG) with the correct voltage based on Rext. You must be careful in choosing Rext, as you should not violate the maximum CL to GND voltage of +/- 1.2V. 

      Iext = Vprog/Rext (current into pin)

    Through the VCL pin, IOUT is programmable from 10 mA to 300 mA by setting Iext (current into VCL pin) from 25 μA to 750 µA by means of a fixed Rext of 10 kΩ and making Vprog variable from 0.25 V to 7.5 V. 

    Therefore two items to watch out for when setting this pin:

1. Current into VCL pin (Iext) should be between 25 μA to 750 µA
2. VCL to GND should not exceed +/-1.2V (Directly at the VCL pin not the same as Vprog which is the voltage at the node prior to Rext)

    Both can be controlled by tunning Rext value. 

Thank you,
Sima

Hi Sima,

is 700mA short circuit current or continuous output current? Wouldn't the output current depend on kind of load connected?

My another question still remains- if I use Vprog=+2.5V and Rext=10k, will it work? what will be value of Vcl in this case?

Thanks,
Shubhangi

Hello Shubhangi,

1. Yes correct. The 700mA when Vcl pin would be short circuit current, and the final continuous current will depend on the kind of load as you said. However, if you put a heavy load, then it will be 700mA and not be limited by the device, and this would not be recommended for continuous use. If you do not see this will be an issue in your design, then you may continue with this configuration. 
   
   
2. If you use Vprog=+2.5V and Rext=10k, then your Iext will equal 250μA. This will work, and Vcl will be equal to 0V. This is because the voltage is "converted" to a useable current Iext. This current is the output from the V/I converter. Confirmed by looking at the system block diagram: 
   
   

            The noninverting pin is connected to ground at the internal amplifier, therefore inverting pin is equal to 0V at that node.

Thank you,
Sima