D12S400-A Datasheet, PDF (7/12 Pages) Delta Electronics, Inc. – Delphi D12S400 Non-Isolated Point of Load DC/DC Modules

DESIGN CONSIDERATIONS
The D12S400 uses a voltage mode controlled buck topology.
The output can be trimmed in the range of 0.8375Vdc to
5.0Vdc by an external resistor from Trim(+) pin to Trim(-).
The converter can be turned ON/OFF by remote control with
positive on/off (ENABLE pin) logic. The converter DC output is
disabled when the signal is driven low. When this pin is floating
the module will turn on.
The converter can protect itself by entering hiccup mode
against over current and short circuit condition. Also, the
converter will shut down when an over voltage protection is
detected.
Safety Considerations
It is recommended that the user to provide a very fast-acting
type fuse in the input line for safety. The output voltage set
point and the output current in the application could define the
amperage rating of the fuse.
FEATURES DESCRIPTIONS
Enable (On/Off)
D12S400 has positive on/off logic, pulling the pin low will turn
off the unit. With the active high function, the output is
guaranteed to turn on if the ENABLE pin is driven above
4.5V. The output will turn off if the ENABLE pin voltage is
pulled below 0.5V. The D12S400 is turned on if the ENABLE
pin is floating.
The ENABLE input can be driven in a variety of way as
shown in Figures 25.
Unit
Vin
Enable
Vout
Trim
GND
GND
Figure 25: Enable Input drive circuit
Over-Current and Short-Circuit Protection
The D12S400 has non-latching over-current and short circuit
protection circuitry. When over current condition occurs, the
module goes into the non-latching hiccup mode. When the
over-current condition is removed, the module will resume
normal operation.
An over current condition is detected by measuring the
voltage drop across the Rds(on) of low side MOSFET.
Rds(on) is affected by temperature, therefore ambient
temperature will affect the current limit inception point.
Output Over Voltage Protection (OVP)
The converter will shut down when an output over voltage
protection is detected. Once the OVP condition is detected,
controller will latch off and can only reset by input voltage or
ON/OFF.
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