FUNCTIONAL DESCRIPTION
INTRODUCTION
FUNCTIONAL DESCRIPTION
INTRODUCTION
The 34727 is a high efficiency, synchronous, buck
regulator, utilizing a voltage mode control architecture with
feed forward. It is capable of providing a 600mA load current
for output voltages of 0.8V to 3.3V, from a single input voltage
rail between 2.7V and 5.5V.
In a buck converter, most of the losses at high output loads
are due to conduction losses in the power train, but at light
output loads, the conduction losses are reduced and most of
the losses become switching losses. Using Freescale’s Z-
mode architecture, the 34727, at light output loads, will
smoothly transition into a lower switching frequency, thus
improving its efficiency.
FUNCTIONAL PIN DESCRIPTION
SUPPLY VOLTAGE INPUT (VIN)
FEEDBACK INPUT (FB)
2.7V to 5.5V DC power input. Bypass with a 4.7µF ceramic
Feedback of the output voltage.
capacitor as close as possible to the VIN and GND pins.
SWITCHING NODE (SW)
GROUND (GND)
This terminal connects to the output inductor. The node
internally connects the drain of both the high side MOSFET
and the low side MOSFET.
Ground.
ENABLE (EN)
NO CONNECTION (NC)
Active high enable input. EN is over-voltage protected to
6.0V, independent of the supply voltage. Drive with a logic
high signal (or connect to VIN) for normal operation. Drive
with a logic low signal, or connect to GND will disable the
34727.
Internally not connected. Connect to GND externally.
MC34727
Analog Integrated Circuit Device Data
Freescale Semiconductor
10
FREESCALE [ Freescale ]
