NCP1597AMNTWG ONSEMI [ON Semiconductor], NCP1597AMNTWG Datasheet - Page 10

• Manufacturer Part Number: NCP1597AMNTWG
• Description: 1 MHz, 2.0 A Synchronous Buck Regulator
• Manufacturer: ONSEMI [ON Semiconductor]

Undervoltage Lockout (UVLO)
from switching when the input voltage is too low to power
the internal power supplies and reference. Hysteresis must
be incorporated in the UVLO comparator to prevent IxR
drops in the wiring or PCB traces from causing ON/OFF
cycling of the controller during heavy loading at power up
or power down.
Overcurrent Protection (OCP)
compares to a voltage level representing the overcurrent
threshold limit. If the current through the high side FET
exceeds the overcurrent threshold limit for seven
consecutive switching cycles, overcurrent protection is
triggered.
engages. First, hiccup mode, turns off both FETs and
discharges the internal compensation network at the output
of the OTA. Next, the IC waits typically 2 ms and then resets
the overcurrent counter. After this reset, the circuit attempts
another normal soft−start. During soft−start, the overcurrent
protection threshold is increased to prevent false
The under voltage lockout feature prevents the controller
NCP1597A detects high side switch current and then
Once the overcurrent protection occurs, hiccup mode
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PROTECTIONS
10
overcurrent detection while charging the output capacitors.
Hiccup mode reduces input supply current and power
dissipation during a short circuit. It also allows for much
improved system up−time, allowing auto−restart upon
removal of a temporary short−circuit.
Pre−Bias Startup
switching when it’s output capacitors are charged anywhere
from slightly above 0 V to just below the regulation voltage.
This situation occurs for a number of reasons: the
converter’s output capacitors may have residual charge on
them or the converter’s output may be held up by a low
current standby power supply. NCP1597A supports
pre−bias start up by holding Low side FETs off till soft start
ramp reaches the FB Pin voltage.
Thermal Shutdown
internal thermal monitoring circuit. If the junction
temperature exceeds the thermal shutdown threshold both
the upper and lower MOSFETs will be shut OFF.
In some applications the controller will be required to start
The NCP1597A protects itself from over heating with an