MPQ8632 HIGH EFFICIENCY 18V SYNCHRONOUS STEP-DOWN CONVERTER FAMILY FOR 4A TO 20A
MPQ8632GVE-15, MPQ8632GVE-20
PIN #
Name Description
Enable. Digital input that turns the regulator on or off. Drive EN high to turn on the
1
EN
regulator; drive it low to turn it off. Connect EN to IN through a pull-up resistor or a
resistive voltage divider for automatic startup. Do not float this pin.
Frequency Set. Require a resistor connected between FREQ and IN to set the
switching frequency. The input voltage and the resistor connected to the FREQ pin
determine the ON time. The connection to the IN pin provides line feed-forward and
stabilizes the frequency during input voltage’s variation.
2
3
FREQ
Feedback. Connect to the tap of an external resistor divider from the output to GND
to set the output voltage. Place the resistor divider as close to FB pin as possible.
Avoid using vias on the FB traces.
FB
SS
Soft-Start. Connect an external capacitor to program the soft start time for the switch
mode regulator.
4
5
AGND Analog Ground. The control circuit reference.
Power-Good. The output is an open drain signal. Requires a pull-up resistor to a DC
6
PG
voltage to indicate HIGH if the output voltage exceeds 91% of the nominal voltage.
There is a delay from FB ≥ 91% to when PG goes high.
Internal 4.8V LDO Output. Powers the driver and control circuits. 5V external bias
can disable the internal LDO. Decouple with a ≥1µF ceramic capacitor as close to the
pin as possible. For best results, use X7R or X5R dielectric ceramic capacitors for
their stable temperature characteristics.
7
8
VCC
BST
Bootstrap. Require a capacitor connected between SW and BST pins to form a
floating supply across the high-side switch driver.
Switch Output. Connect to the inductor and bootstrap capacitor. The high-side switch
drives these pins up to VIN during the PWM duty cycle’s ON time. The inductor
current drives the SW pin negative during the OFF-time. The low-side switch’s ON-
resistance and the internal Schottky diode holds the negative voltage. Connect all
SW pins using wide PCB traces.
15-18,
25-29
SW
System Ground. Reference ground of the regulated output voltage. PCB layout
requires extra care. Connect using wide PCB traces.
10-14, 19-23
9, 24
PGND
IN
Supply Voltage. Supplies power to the internal MOSFET and regulator. The
MPQ8632GVE operate from a 4.5V-to-18V input rail. If 5V external bias is tied to
VCC pin, the input voltage can be low as 2.5V. Requires an input decoupling
capacitor. Connect using wide PCB traces and multiple vias.
MPQ8632 Rev.1.24
8/28/2013
www.MonolithicPower.com
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