FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
The soft-start sequence also occurs upon recovery from any
fault condition.
OVER-TEMPERATURE PROTECTION
To limit its operating temperature, the 34727 shuts down if
the junction temperature of the switching MOSFET
surpasses 140°C. If the junction temperature subsequently
drops to 130°C, the 34727 re-starts.
UNDER-VOLTAGE LOCK-OUT
The UVLO threshold is set to 2.7V for rising VIN, and to
2.5V for falling VIN. For a VOUT of 3.3V, the VOUT value will
track VIN below 3.6V until the 2.5V falling VIN threshold is
reached.
SOFT-START OPERATION
To limit the in-rush current, an internal timer controls the
output voltage ramp after the part is enabled. The start-up
time is internally set to approximately 2.0ms and is
If the UVLO falling threshold is met, the part shuts down
and will power up again with soft-start, when the UVLO rising
threshold is surpassed.
independent of input voltage, output voltage, or load current.
MC34727
Analog Integrated Circuit Device Data
Freescale Semiconductor
13
FREESCALE [ Freescale ]
