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3.12
Power Good
When the input voltage fails, the Power Good function pro-
vides a time delay before the Main DC Output is switched
off. This time delay can be used to monitor the PWR_
GOOD signal for a warning or to save key data.
The PWR_GOOD signal is provided on J3 Pin 9 (PWR_
GOOD).
The function uses the open collector circuit as shown in Fig.
12, p. 9.
Power Supply Unit
3.3V_µC
1 kΩ
Fig. 12: PWR_GOOD (Power Good) - Circuit diagram
As soon as AC input voltage and DC output voltage are
in the predefined range, the PWR_GOOD signal is set to
HIGH.
When the input voltage is removed and remains absent
for at least 10 ms, the PWR_GOOD signal is set to LOW.
Another 10 ms later (minimum interval), the Main DC Out-
put is switched off. See Fig. 13, p. 9.
AC Input
Main DC Output
PWR_GOOD
Fig. 13: PWR_GOOD (Power Good) - Signal sequence
Pull the PWR_GOOD signal to +5VSB (J3 Pin 1, J3 Pin 2
or J3 Pin 8) (or another voltage in the customer system) by
a resistor. The resistor is needed to limit the collector cur-
rent.
The maximum voltage for PWR_GOOD is 30 V, the maxi-
mum sink current is 1 mA.
IMA-x1000-xx-Series_Application_Note_V4.0_XX_EN_2019-08-19
PWR_GOOD
J3
5VSB_RTN
≥20 ms
10 ms
≥10 ms
3.13
Output voltage ripple and noise
Ripple and noise are measured at 20 MHz by using a
twisted pair of load wires terminated with a 0.1 µF film
capacitor and a 10 µF tantalum capacitor.
NOTE: The output ripple cannot be measured accurately if
the probe ground lead from the oscilloscope is too long.
Power supply unit
Fig. 14: Ripple measurement setup
3.14
Remote +V_SENSE, -V_SENSE
NOTICE
Do not short or reversely connect +V_SENSE and
-V_SENSE. Doing this can cause damage to the
power supply.
J3 Pin 13 (+V_SENSE) and J3 Pin 14 (-V_SENSE) can be
used to compensate voltage drop on output cable.
There is a voltage drop on the output cable that connects
the Power Supply Unit with the load. The voltage drop is
particularly high with heavy loads.
The Remote SENSE circuit can compensate a voltage drop
of maximum 200 mV on the output cable. The 200 mV drop
is the total combined voltage drop across both DC return
and DC Output+.
To use this function, the twisted pair of the V_SENSE sig-
nals and the input of the load have to be connected.
Electrical functions
Load
Probe
Scope 20 MHz
9
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