What is Set Up, Rise, Hold Up Time

    Set up time (ton): The time from power on to 90% of rated output voltage, or from AC powered on to operation of S.P.S. Rise time (tr): The time it takes for output voltage to rise from 10% to 90% of rated value. It is usually within 50ms. Longer period than that might lead to [...]

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    How to Calculate Maximum Output Current/Power

    Maximum output power equals to Vout × Iout. Iout should be decreased to keep output power within rated value when Vout is increased. For instance, a model with rated voltage of 5V and maximum output current of 10A, the maximum allowed output current would be 9A while output voltage is set at 5.5V. Please note [...]

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    Output Voltage/Tolerance/ Adjustment Range

    The measurement of output voltage is defined to be at the output terminal of S.P.S. If voltage is measured at the load end, the measurement would deviate due to voltage drop on wiring. The voltage tolerance is the biggest voltage variation measured during simultaneous line and load change. In general, the tolerance accounts for line [...]

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    Leakage Current

    Leakage current is the current flowing from the protective earth (PE) conductor, such as metal enclosure, of equipments to frame ground (FG). Due to EMI requirements in S.P.S., there are Y capacitors (C2 and C3 in Figure 2.2) connected in between AC L/N and PE conductor. A low current will flow through the Y-caps to [...]

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    What is Inrush Current – Details explained

    When AC is initially powered ON, a peak current is required to charge the empty bulk capacitor. This momentary peak is also called the inrush current. The magnitude of the inrush current varies according to the type of current limiting circuit used. S.P.S. commonly uses a thermistor to limit inrush current. The high resistance of [...]

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    Over Temperature Protection (O.T.P.)

    This protection is to prevent internal components of S.P.S. from overheating and damage, or to prevent decrease in lifetime due to high ambient temperature, overloading, or malfunction of S.P.S. (e.g. damaged cooling fan). The fault conditions needs to be cleared then S.P.S. would recover automatically or restarts by manual re-power on after internal temperature drops [...]

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    Over Current Protection (O.C.P.)/ Overload Protection (O.L.P.)

    When the output power or current reaches the range of O.L.P. /O.C.P. (typically 105%~150% of rated power/current), the S.P.S. would be protected by decreasing or cutoff of output power. The protection modes for over current/overload are categorized into the following types: Protection Types: (1) Foldback Current Limiting Output current is folded back to 20% or [...]

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    Over Voltage Protection (O.V.P.)

    When output voltage functions abnormality (e.g. lost of regulation), it could exceed the rated value. In consequence of that, O.V.P. is triggered to protect end equipments from damage. The protection modes for over voltage are categorized into the following types: Protection Types: Shut Off S.P.S. restarts by manual AC re-power on of after fault condition [...]

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    What is Power Supply Ripple Noise – Details Explained

    An AC waveform can be identified on the DC output of a S.P.S., which is shown in Figure 2.4. There are two AC components, also known as Ripple and Noise (R&N), on the DC output. The first one, coming from sine wave rectification, is at a low frequency which is 2 times of the input [...]

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