MIL-PRF-49404A(CR)
4.5 Methods of inspection.
4.5.1 Output voltage and output current. Output voltage and current shall be measured to
verify that the regulator is capable of supplying 60 detectors at 6 mA each or a total of 0.36
amperes. A resistive load of 8.25 ohms, ±1% shall simulate the detector load. The loaded output
voltage shall be measured at nominal input (+9.6 and +4.8 Vdc), high input (+11.0 and +5.5
Vdc), and low input (+8.0 and +4.0 Vdc) voltage conditions. Failure to meet the requirements of
3.5.1 shall constitute failure of this test.
4.5.2 Ripple rejection. With the regulator loaded (4.5.1), ripple rejection shall be
measured by modulating the input supply with a sinusoidal signal which provides a variable
input ripple. An oscilloscope shall be used to observe the ripple inserted on the input and the
ripple appearing on the output. Ripple rejection is defined as:
Ripple Rejection = 20 log [Input voltage ripple/Output voltage ripple]
Ripple rejection shall be measured from 30 Hz to 20 KHz. ( At the following frequencies:
30 Hz, 100 Hz, 1 kHz, 10 kHz, 20 kHz.) The input voltages shall be set at a minimum and
maximum (3.5.1) for separate tests. Failure to meet requirements of 3.5.2 shall constitute failure
of this test.
4.5.3. Output impedance. Output impedance shall be measured using a varying load
network with a modulated input and an oscilloscope to measure the AC output current and
voltage. Output impedance shall be measured at the following frequencies: 30 Hz, 100 Hz, 1
KHz, 10 KHz, and 20 KHz. Output impedance shall be defined as the ratio of the peak-to-peak
output current change induced by the varying load network. Failure to meet the requirements of
3.5.3 shall constitute failure of this test.
4.5.4 Output noise. Output noise voltage may be determined by measuring wideband rms
noise voltage at the regulator output with a true-rms voltmeter using the test setup and test
methods of 4.5.1. Since the noise output of the regulator is very low, it may fall under the
minimum threshold level of a true-rms voltmeter. The measurement may then be performed
using a low-noise amplifier, with a single RC roll-off, connected at the +3 Vdc output of the
regulator.
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