Power Supply Rejection Ratio
Measurement
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Using the Bode 100 and the Picotest J2120A Line Injector
小学生垃圾分类
目前最赚钱的行业Voltage
Regulator
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Table of Contents
1 Executive Summary (3)
2 Measurement Task (4)
3 Measurement Setup & Results (5)
3岁宝宝咳嗽3.1 Measurement Setup (5)
3.2 Device Setup (7)
3.3 Calibration (8)
3.4 Measurement (8)
4 Conclusion (9)
1 Executive Summary
This application note shows how the Power Supply Rejection Ratio, or PSRR of a linear voltage regulator (LM317) can be measured using the Bode 100 and additional accessories.
The same techniques can be ud to measure switching regulators as well.
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The measurements are performed on the PICOTEST Voltage Regulator Test Standard (VRTS) testing board1 using the PICOTEST J2120A Line Injector.
2 Measurement Task
The PSRR of the LM317 linear voltage regulator is measured with the Bode 100 and the PICOTEST J2120A line injector.
A capacitor is then connected to the output of the regulator and the PSRR is again measured from 10 Hz to 10 MHz.
The PICOTEST VRTS kit is ud as the basis for the testing. The VRTS can be ud to help perform most of the common voltage regulator measurements using the Bode 100 in conjunction with the PICOTEST Signal Injectors. The VRTS kit includes the regulators and capacitors ud for the measurements in this application note.
Voltage Regulator Test Standard board, Source (1)
3 Measurement Setup & Results
The PSRR describes how a signal on the DC input voltage of the regulator system is
transmitted to the regulated output. The PSRR is generally measured in dB and defined to be:
Where and are the AC ripple of the input and output voltage, respectively.
Depending on the definition the PSRR can be a negative or positive number. Using the above definition, the PSRR generally is a negative number.
3.1 Measurement Setup
The PSRR can be measured by applying a sinusoidal ripple on the supply voltage and measuring the gain from input to output of the regulator.
The PICOTEST J2120A Line Injector allows you to add the sinusoidal output voltage of the Bode 100 to the DC-supply voltage of the regulator. The PSRR is then measured by connecting two voltage probes to the input and output of the regulator. In this ca two 1:1 voltage probes are ud.
The following figure shows the principle measurement tup:珠心算怎么学
PSRR measurement tup, Source (1)
GND
PSRR
