TIPD158: TIPD158

Ankur Dubey

Part Number: TIPD158
Other Parts Discussed in Thread: XTR117

We are implementing the same circuit as given in TIPD158, but facing an issue of transistor's collector and emitter being shorted after giving 24 V loop supply on collector, and thus damaging the transistor and R5 in circuit attached.

the steps and points which we are following in our circuit are as follows-

1) We are giving input to opamp through R2 i.e. 1-3V

2) VReg supply coming through R1 from a regulator of 3.3V output.

3) the components used are

OPAMP- LM324n / OPA192ID

Transistor- TP122/ BC548

PFA the images attached as of implemented circuit as well as from TIPD158

over 5 years ago

0 Garrett Satterfield over 5 years ago

TI__Expert 5820 points

Hi Ankur,

The only way I can see this happening is if the loop is not being correctly regulated and a large current flows causing damage. Does this happen as soon as the power supply is connected? What is the current provided by the supply and voltage at the base of TIP122?

Thanks,
Garrett

0 Garrett Satterfield over 5 years ago in reply to Garrett Satterfield

TI__Expert 5820 points

Hi Ankur,

Any update on this thread?

Thanks,
Garrett

0 Ankur Dubey over 5 years ago in reply to Garrett Satterfield

Intellectual 385 points

yes, we are now using XTR117AIDGQT circuit for current loop transmitter, The problem in that circuit is that, when we are connecting a resistor across Pin 4 and Pin 3 of XTR117 IC we can see the output in 4-20mA.

But as in figure attached, the loop connection with our different board as shown in circuit with blue line, we are not able to see the current output across R7.

0 Garrett Satterfield over 5 years ago in reply to Ankur Dubey

TI__Expert 5820 points

Hello Ankur,

In the configuration you posted above you will not see the loop current flowing through the analog input. The loop current flows from the loop power supply through the transmitter and load resistor. The sense resistor of the analog input should take the place of Rload. Connect X2-3 to GND of the loop power supply and X2-2 pin 4 of XTR117 to pass the loop current through R7.

Thanks,
Garrett

0 Garrett Satterfield over 5 years ago in reply to Garrett Satterfield

TI__Expert 5820 points

Hi Ankur,

Any update on this thread?

Thanks,
Garrett

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TIPD158: TIPD158