Author: Michael Koltai

DAC Interface Circuit

This “DAC Interface”  circuit is a precision buffer amplifier for a DAC output. It is scaled to provide a 10V output @ 10mA with a +1V input voltage. This type of current source can be very useful in industrial interface applications.

A R-R output op amp with an input common-mode range that includes its negative supply rail, such as an OPA251, is required for single- supply operation.

An external NPN transistor  is used to off- load the circuit power dissipation from the precision op amp U1. Re- scaling this circuit with other transistors can result in output current capability of a many amps. (Circuit is created by Neil P. Albaugh  TI – Tucson)

DAC Interface Circuit:

Online Simulation of the DAC Interface 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

Comparator With AC Hysteresis

Using AC hysteresis solves the threshold offset problem caused by conventional DC hysteresis. Place a small capacitor to feed back the output edge transition into the comparator non- inverting input to provide momentary positive feedback. This sharpens the comparator response as well as reducing the tendency to “chatter” at the switching point. If the RC time constant of R1C1 is << the waveform period, the comparator trip point hysteresis will have settled back to 0V by the time the next threshold- crossing takes place. (Circuit is created by Neil P. Albaugh  TI- Tucson)

Comparator With AC Hysteresis circuit:

Online Simulation of a Comparator with AC Hysteresis 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

Zoom amplifier circuit

This “unusual zoom amplifier circuit” allows you to “zero out” a DC voltage and then amplify a small AC signal which is superimposed on the much larger DC level. When switch SW1 is closed, both INA128 inputs see the same AC + DC level and its high common- mode rejection results in zero volts output. When SW1 is opened, the DC level is stored on C1 but now the AC signal is applied to only the inverting input where it is amplified by a factor of 1000x. The droop rate of C1 depends on the leakage of SW1 and the input bias current of U1.Using a glass reed relay and an INA116 (Ib = 5fA typ), extremely low droop rate can be achieved. A high insulation resistance dielectric capacitor is necessary– teflon, polystyrene, etc. (Circuit is created by Neil P. Albaugh  TI- Tucson)

Zoom amplifier circuit:

Online Simulation of a Zoom  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

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