MP2227 – 24V, 3A, 1.3MHz SYNCHRONOUS STEP-DOWN CONVERTER
PIN FUNCTIONS
Pin #
1
2
3
4, 5
6,7
8
9
Name
FB
POK
IN
GND
SW
BST
VCC
Description
Feedback. This is the input to the error amplifier. An external resistive divider connected
between the output and GND is compared to the internal 0.8V reference to set the
regulation voltage.
Open Drain Power Good Output. “HIGH” output indicates VOUT is within ±10% window.
“LOW” output indicates VOUT is out of ±10% window. POK is pulled down in shutdown.
Input Supply. This supplies power to the high side switch. A decoupling capacitor to ground
is required close to this pin to reduce switching spikes.
Ground. Connect these pins with larger copper areas to the negative terminals of the input
and output capacitors.
Switch Node Connection to the Inductor. These pins connect to the internal high and low-
side power MOSFET switches. All SW pins must be connected together externally.
Bootstrap. A capacitor between this pin and SW provides a floating supply for the high-side
gate driver.
Bias Supply. Provide 5V to this pin when the input voltage is less than 5V. Otherwise it
does not need external supply. This supplies power to both the internal control circuit and
the gate drivers. A decoupling capacitor to ground is required close to this pin.
Enable and Frequency Synchronization Input Pin. Forcing this pin below 0.4V shuts down
the part. Forcing this pin above 1.6V turns on the part. Applying a 1MHz to 2MHz clock
signal to this pin synchronizes the internal oscillator frequency to the external source. To
enable the device, connect this pin to V
IN
through a 100kΩ resistor. When V
IN
is less than
5V and V
CC
is externally biased, this pin can also be connected to V
CC
through a 100kΩ
resistor.
10
EN/SYNC
MP2227 Rev. 1.1
11/21/2011
www.MonolithicPower.com
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