INA592: Voltage to Current converter Using INA592

doudu vamshi

Part Number: INA592

INA592 is used for Voltage to Current conveter. My circuit expected to work as

i. Sink mode Configuration: Vin below 1.25V current(0-20mA) should flow and if Vin above 1.25V then 0mA should flow.

above is working fine if My INA592 Supply and Loop Resistor R7 connected to same supply.

But when INA592 Connected to 33V and Loop Resistor R7 connected to 24V with common ground. The circuit is working for Vin from 0-2.5V and current is varying from -20mA to 20mA.

I have attached the schematic and waveform.

1 month ago

0 Robert Clifton56 1 month ago

TI__Mastermind 28280 points

Hi doudu,

Can you please attach the Tina simulation file as well?

doudu vamshi said:
But when INA592 Connected to 33V and Loop Resistor R7 connected to 24V with common ground. The circuit is working for Vin from 0-2.5V and current is varying from -20mA to 20mA.

I'm having a little trouble understanding the problem. Is the issue that from 1.25V and above, it's not clamping the output voltage to 0mA?

Best Regards,

Robert Clifton

0 doudu vamshi 1 month ago in reply to Robert Clifton56

Prodigy 70 points

Yes Robert

0 doudu vamshi 1 month ago in reply to Robert Clifton56

Prodigy 70 points

Sink Mode.TSC

0 doudu vamshi 1 month ago in reply to doudu vamshi

Prodigy 70 points

For your understanding, Please observe the Iout by simulating the waveforms by connecting Vcc=24V and Vcc=33 then compare it.

0 Robert Clifton56 1 month ago in reply to doudu vamshi

TI__Mastermind 28280 points

Hi Doudu,

I wanted to let you know that I'm still looking into this and hope to figure it out within the coming days.

Thank you,

Robert Clifton

0 Robert Clifton56 1 month ago in reply to Robert Clifton56

TI__Mastermind 28280 points

Hi Doudu,

I have found that you need to have V3 and VCC be equal to each other for the clamp to work properly.

This is caused by the fact that the output of the INA592 is able to go beyond the V3 supplies (when set to 24V). This induces current up to about 28mA on the output. Compared that to when you set the supplies equal to each other, no very little current flows once the INA592 is slammed close to the positive supply rail.

7522.Sink Mode.TSC

Best Regards,

Robert Clifton

0 doudu vamshi 1 month ago in reply to Robert Clifton56

Prodigy 70 points

Hi Robert,

That we know earlier only. The output equation if Vout = (V+-V-)*Gain +Vref. Why increasing VCC compared to V3 is effecting the Vout is my question.

My requirement is Vcc is more than V3 only.

0 Robert Clifton56 1 month ago in reply to doudu vamshi

TI__Mastermind 28280 points

Hi Doudu,

I'm sorry I didn't explain it well.

Looking at DC when V2 is a voltage that will cause the output if U1 (INA592) push its output close to its supply rail, if that supply rail is higher than V3, current will flow from VOUT to V3.

See when the supply voltage and V3 match closely, very little current flows:

Versus when they don't match, you can see the current is higher as VOUT is at a higher voltage than V3:

Best Regards,

Robert Clifton

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INA592: Voltage to Current converter Using INA592