Category: Application Circuit

This current shunt monitor circuit allows a current measurement to be made by measuring the voltage drop across a shunt resistor in the “high side” of a power supply. The INA193 is capable of operating with a common- mode voltage of up to +80V and its CMV range is not a function of
its supply voltage.  The INA193 provides a differential voltage gain of 20V/V and its recommended full- scale input  voltage is 100mV.  An INA194 provides a gain of 50V/V and an INA195 provides a gain of 100V/V. R1 & R2 together with C2, C3, & C4 provide differential and common-mode filtering and are recommended for switching power supplies. The two resistors should be carefully matched (1% tolerance) as well as capacitors C3 & C4 (5% or better tolerance). Resistors of 100 ohms will give a gain error of slightly under 2%. (Circuit is created by Neil P. Albaugh,  TI – Tucson)

Current Shunt Amplifier circuit:

Online Simulation of the Current Shunt Amplifier Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or  watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

Proportional- Integral Temperature Control

A high- accuracy temperature control amplifier can be realized with a proportional- integral amplifier response; the integrator function drives the steady- state error to zero.

An autozero instrumentation amplifier INA326 achieves very low offset and drift as well as virtually eliminating the loop error due to 1/f noise.

R6 is used simply to provide a feedback path during a DC analysis. This circuit requires an overall feedback path (TEC, etc) to achieve a steady-state operating point.

This amplifier allows temperature control loop stability within in a few tens of milli- degrees. Bypass capacitors are not shown. This circuit can be used with a DRV593 or an OPA569 TEC driver circuit. (Circuit is created by Neil P. Albaugh  TI – Tucson)

     Proportional- Integral Temperature Control circuit:

Online Simulation of the Proportional- Integral Temperature Control Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud  and analyze the circuit yourself, or  watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

Online Simulation of the Universal Voltage Reference Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud and analyze the circuit.

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

Online Simulation of the Differential Amplifier CMRR Trim Circuit

Adding a negative- resistance circuit (U2) to the REF pin allows the CMRR of a differential amplifier or instrumentation amplifier to be trimmed. This is done by applying a sine wave of 20Vp-p to the inputs of U1 and adjusting the potentiometer P1 for a minimum signal at the amplifier output.

By using an AC source the DC input offset errors do not effect this trim.

At 50% rotation of P1 the resistance of R8 cancels the resistance of R5, appearing as a virtual ground to the REF pin. As P1 is adjusted from end to end, R5 is “undercancelled”or “overcancelled” by R8 and the resistance presented to the REF pin goes from a real, positive resistance to a negative resistance. This allows the internal resistor network of U1to be trimmed for maximum CMRR. ( Circuit is created by Neil P. Albaugh  TI – Tucson )

Differential Amplifier CMRR Trim Circuit

Online Simulation of the Differential Amplifier CMRR Trim Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud and analyze the circuit.

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

Cload Compensation

Driving a capacitive load directly with an op amp is an invitation to instability or oscillation. The amplifier’s output resistance and the load capacitance form a pole  in the feedback circuit. This inserts additional phase shift which will reduce the loop phase margin– perhaps to zero.

The effects of reduced phase margin can be  seen in the waveform ringing and gain peaking plots below. By isolating the capacitance with a small resistor (R1) and providing local high-frequency feedback (C2),  very little phase margin is lost. The voltage drop across R1 is sensed by a DC feedback connection (R2) to the circuit output and thereby reduced to virtually zero.
Note the improvement gained by compensating for a Cload!  (Circuit is created by Neil P. Albaugh,  TI – Tucson)

Online Simulation of the Cload Compensation Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud and analyze the circuit.

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com