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| university:courses:electronics:electronics-lab-nr [21 Dec 2017 06:18] – Trecia Agoylo | university:courses:electronics:electronics-lab-nr [11 Jan 2021 11:02] (current) – Fixed bad link for OP482 Ioana Chelaru |
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| ====Testing supply headroom==== | ====Testing supply headroom==== |
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| To test the headroom requirements for +V<sub>DD</sub>, disconnect the fixed positive power supply from +V<sub>DD</sub> and remove any supply decoupling capacitors. Be sure to turn off the power supplies before making any changes or additions to your breadboard. Now connect +V<sub>DD</sub> to AWG 1. Set AWG 1 to trapezium (trapezoid) waveform at 100 Hz. Set the amplitude to 5V with a 2.5V offset for a 0 to +5V swing. Connect scope channel 1 to the output of AWG1 and connect scope channel 2 to -V<sub>REF</sub> of the first example circuit at pin 14 of the OP482. Use the oscilloscope instrument in the XY mode, scope channel for X and scope channel 2 for Y. Start AWG 1 and turn on the fixed negative 5V power supply. Record the minimum +V<sub>DD</sub> voltage where -V<sub>REF</sub> starts to remain constant at -1.25V. | To test the headroom requirements for +V<sub>DD</sub>, disconnect the fixed positive power supply from +V<sub>DD</sub> and remove any supply decoupling capacitors. Be sure to turn off the power supplies before making any changes or additions to your breadboard. Now connect +V<sub>DD</sub> to AWG 1. Set AWG 1 to trapezium (trapezoid) waveform at 100 Hz. Set the amplitude to 5V peak-to-peak with a 2.5V offset for a 0 to +5V swing. Connect scope channel 1 to the output of AWG1 and connect scope channel 2 to -V<sub>REF</sub> of the first example circuit at pin 14 of the OP482. Use the oscilloscope instrument in the XY mode, scope channel for X and scope channel 2 for Y. Start AWG 1 and turn on the fixed negative 5V power supply. Record the minimum +V<sub>DD</sub> voltage where -V<sub>REF</sub> starts to remain constant at -1.25V. |
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| To test the headroom requirements for -V<sub>SS</sub>, reconnect +V<sub>DD</sub> to the fixed positive power supply. Disconnect the fixed negative power supply from -V<sub>SS</sub> and remove any supply decoupling capacitors. Now connect -V<sub>SS</sub> to AWG 1. Set the amplitude to 5V with a -2.5V offset for a 0 to -5V swing. Start AWG 1 and turn on the fixed positive 5V power supply. Repeat your measurements of pins 14 of the OP482 recording the lowest value for -V<sub>SS</sub> where the reference voltage is constant. | To test the headroom requirements for -V<sub>SS</sub>, reconnect +V<sub>DD</sub> to the fixed positive power supply. Disconnect the fixed negative power supply from -V<sub>SS</sub> and remove any supply decoupling capacitors. Now connect -V<sub>SS</sub> to AWG 1. Set the amplitude to 5V peak-to-peak with a -2.5V offset for a 0 to -5V swing. Start AWG 1 and turn on the fixed positive 5V power supply. Repeat your measurements of pins 14 of the OP482 recording the lowest value for -V<sub>SS</sub> where the reference voltage is constant. |
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| =====Directions Step 3:===== | =====Directions Step 3:===== |
| Repeat the supply headroom tests you did in Step 2 for this configuration. Are there any differences? | Repeat the supply headroom tests you did in Step 2 for this configuration. Are there any differences? |
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| | <WRAP round download> |
| | **Resources:** |
| | * Fritzing files: [[downgit>education_tools/tree/master/m2k/fritzing/neg_voltage_ref_bb | neg_voltage_ref_bb]] |
| | * LTspice files: [[downgit>education_tools/tree/master/m2k/ltspice/neg_voltage_ref_ltspice | neg_voltage_ref_ltspice]] |
| | </WRAP> |
| ====For further reading:==== | ====For further reading:==== |
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| [5] [[university:courses:electronics:electronics-lab-7|Activity 7. Zero gain amplifier (BJT)]]\\ | [5] [[university:courses:electronics:electronics-lab-7|Activity 7. Zero gain amplifier (BJT)]]\\ |
| [6] [[university:courses:electronics:electronics-lab-8|Activity 8. Stabilized current source (BJT)]]\\ | [6] [[university:courses:electronics:electronics-lab-8|Activity 8. Stabilized current source (BJT)]]\\ |
| [[http://www.analog.com/static/imported-files/data_sheets/OP282_OP482.pdf]] OP482 datasheet | [[adi>OP482]] datasheet |
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| Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]] | Return to Lab Activity [[university:courses:electronics:labs|Table of Contents]] |
