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dc1899af
DEMO MANUAL DC1899A
Figure 4. Short-Circuit Test (2A/Div)
Power-Up into Output Short
Short the output to ground with a wire. Place the current
probe on this wire. Turn on the rail and record the current
shape. The maximum current should be in the 11.6A to
16.9A range. The LTC4228-1 latches off after overcurrent
condition, but the LTC4228-2 automatically retries after
200ms to 450ms.
IDEAL DIODE FUNCTIONALITY TEST
Use an individual 12V power supply for each rail; connect
the two outputs together at a common load. Adjust each
input voltage to 12V with maximum possible accuracy.
In this test, both rails are active and small variations in
the input voltage will force one channel off and the other
channel on. Place a voltmeter between IN1 and IN2 turrets
to measure the difference between two input voltages.
Activate both rails and keep a load around 1A to 3A. Ad-
just the input voltage level of one supply such that IN1 is
QUICK START PROCEDURE
40mV more positive than IN2. Verify that only channel 1
is drawing current. Repeat this test with IN1 at –40mV
with respect to IN2. In this case channel only channel 2
is drawing current.
PRIORITIZER FUNCTIONALITY TEST
The DC1899A is assembled with components to implement
a power prioritizer with channel 1 having the higher priority.
Place JP7 PPR_SEL (power priority select) jumper in
position ON2 and JP5 RON2_SEL (ON2 select) in posi-
tion OFF.
Apply independent supply voltages (12V) to both inputs.
Channel 1 will be connected to load. Reduce channel 1
input voltage until it reaches an undervoltage condition
and D6 (PWRGD2) lights. At the same time channel 2
power supply will deliver power to the load.
dn1899a F04
CURRENT PROFILE DURING
SHORT-CIRCUIT TURN-ON
