XTR111: Output current

Liu Yang

Part Number: XTR111
Other Parts Discussed in Thread: INA592, TINA-TI, BUF634A

Hi team,

Can this output 200mA current
According to the formula, the maximum voltage we provide is 5V, which is output from DAC
The set pin of XTR111 is connected to 1200ohm resistor.

Beat Regards,
Tom Liu

over 3 years ago

0 kai klaas69 over 3 years ago

Guru 140200 points

Hi Liu,

10 x 5V / 1200R = 41.67mA.

Keep in mind that according to datasheet the XTR111 is only capable of delivering currents from 0mA to 36mA.

Kai

0 Iwata Etsuji over 3 years ago in reply to kai klaas69

TI__Expert 6330 points

Hi Liu,

As Kai pointed out, it is difficult to recommend for you to use XTR111 in your expected output.

While, how about the discrete constant current output circuit, such as the application note in below link.

http://www.ti.com/lit/an/snoa474a/snoa474a.pdf

I will attach an example for 200mA output circuit in TINA-TI simulation file with INA592.

HowlandCurrentPump-VCCS592+BUF.TSC

If you could see this simulation, you might consider replace BUF634A with NMOS or NPN BJT.
When you will consider such replacement, please take care about the phase margin and note that gate/base resistor and some snubber could help to improve the phase margin due to gate/base caps as the cap load for INA592.

Thank you and Best regards,
Iwata Etsuji

0 hechengwang over 3 years ago in reply to kai klaas69

Prodigy 60 points

thank you very much，i am so idiot ,i am very frustrated that i am a blind with eyes!!!!!

Say one more word,is that the peripheral circuit right or wrong ,can it work normally???

0 hechengwang over 3 years ago in reply to Iwata Etsuji

Prodigy 60 points

thank you ，could you make a simulation model of xtr111?

0 Iwata Etsuji over 3 years ago in reply to hechengwang

TI__Expert 6330 points

Hi hechengwang,

As you pointed out, there is no TINA model on the XTR111 product folder, unfortunately.

However, its "unofficial"(theoretical) TINA simulation model is available on this E2E, as you can see in the below link.

https://e2e.ti.com/support/amplifiers/f/14/t/170869

I hope it could help to validate your schematic.

Thank you and Best regards,
Iwata Etsuji

0 hechengwang over 3 years ago in reply to Iwata Etsuji

Prodigy 60 points

thank you ,dear Iwata Etsuji.

Used the circuit simulation you made,It is indeed an adjustable constant current source circuit

Therefore, I modified your simulation circuit according to my own circuit,but it's not a constant current source circuit.
why?Could you correct it for me,thank you very much.

my.XTR111_User.TSC

0 kai klaas69 over 3 years ago in reply to hechengwang

Guru 140200 points

Hi Hechengwang,

this is the simulation of your circuit. Please note that I changed the burden resistance (load) to 100R:

hechen_xtr111.TSC

Kai

0 hechengwang over 3 years ago in reply to kai klaas69

Prodigy 60 points

thank you very much， now I know how to use this chip 。the input voltage,output resistance,output current,and RSET resistance should all be considered.

The capacitance doesn't seem to be working。Even if I remove all the capacitances, it doesn't affect the output。What is the appropriate value of the capacitance If i use capacitors。

0 Iwata Etsuji over 3 years ago in reply to hechengwang

TI__Expert 6330 points

Hi hechengwang,

Honestly speaking, the appropriate value of the output cap for XTR111 is depending on the system requirements such as noise immunity, radiation noise, intrinsic safety, et cetera.

While, you can also refer it to the subsection "DYNAMIC PERFORMANCE" in the XTR111 data sheet, especially its Fig.39 and 40.
And you can see some comments on the output cap in the TI design.

https://www.ti.com/tool/TIDA-00760

https://www.ti.com/tool/TIDA-01536

Thank you and Best regards,
Iwata Etsuji