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dc2024afa
DEMO MANUAL DC2024A
Quick start proceDure
A common sneak path for current is the third wire
grounds used on power cords of test equipment in use.
Using ground lifting connectors at the wall outlet won’t
necessarily alleviate these effects since most equipment
has line bypassing capacitors between the mains voltage
and local chassis ground.Isolating test equipment using
line isolation transformers with low primary to secondary
capacitance is recommended.Probe ground leads may
intercept induced fields from the high current paths and
should be minimized or avoided
Another method to remove these artifacts is the use of
a differential scope probe connected between the signal
to be observed and a ground connection located close to
the point of measurement.
Also be careful to not allow an open ground from the
power supply or load to cause return current through the
grounds of the various devices connected to the demo
board. This may present a fire hazard or cause damage
to the test equipment.
The DC2024A is set up to operate in a 12V system at
current levels up to 100A. At 100A, the MOSFETs are
dissipating 3.75W each and additional air flow may be
needed to keep them within safe thermal operating limits
for continuous operation.If additional current is required
without sufficient air flow,multiple MOSFETs should be
connected in parallel with the existing MOSFETs to lower
the I2R losses.
Jumper Positions
JUMPER NAME POSITION
JP1 CLK EXT
JP2 ON INTVCC
JP3 ADR0 NC
JP4 ADR1 NC
JP5 ADR2 NC
JP6 WRITE PROTECT LOCK
Powering Up
Connect power supply capable of 120A at 0V to 20V to
the 12V input as shown in Figure 1. Verify cabling shown
in extra bold lines is capable of carrying 100A safely.The
GND connection does not handle high current so no high
current cabling is required.
Generally, an electronic load will be used.If this is true,
use it in the constant resistance mode.Use in constant
current will prevent start up because of current foldback
in the LTC4282. Current foldback is used to minimize
dissipation in the MOSFETs used as pass devices with
the LTC4282. To effect this,current is initially limited to
approximately 1/3 of full limit until the output voltage is
above 10V. If a constant current load is used and set to
100A, the LTC4282 will not start up and a current fault
will be reported.
UV/OV Thresholds
With no load on the output,slowly increase the voltage
on the input to the board.Observe the input voltage when
LED D2 (OUT) illuminates.This voltage should be between
10.7Vand 11.4V.Continueincreasing thevoltage untilD2is
extinguished.Thisshould occur between14.4V and 15.3V.
Output Voltage Slew Rate
With no load connected,observe the output voltage
between turret 12VOUT (E5), and GND.Apply 12V to the
12VIN connector.The output voltage should slew from 0V
to 12V in 10ms to 25ms.
Output Current Limit
Turn off power supply and connect electronic load to the
DC2024 as shown in Figure 1. Disable electronic load.
Adjust power supply to 12V and verify its current level is
set to >120A.
Slowly increase conductance of the electronic load while
monitoring current.As the load increases to around 100A,
the output voltage and current will fall to zero.Note the
current where this occurs. This should be 95A to 105A.
Ability to Charge Output Capacitor
Turn off power supply and disconnect electronic load.
Replace load with a 10,000µF capacitor rated at 15V or
greater. Turn on power supply and observe that the output
voltage rises to 12V indicating the DC2024 has connected
tothe load andsuccessfully chargedtheoutput capacitance.
Monitor the current during the period when the capacitor
is charging, it should be a maximum of 12A.
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