TM
MP1423 – 3A, 23V, 385KHz STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
Soft-Start
SS
1.5A Resistive Load
Efficiency Curve
C
Open, V = 10V, V = 3.3V,
IN OUT
V
= 7V
IN
100
90
80
70
60
50
V
=5.0V
IN
V
EN
5V/div.
V
=2.5V
IN
V
OUT
2V/div.
V
=3.3V
IN
I
L
1A/div.
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5
MP1423-TPC02
LOAD CURRENT (A)
MP1423-TPC01
V
V
EN
EN
5V/div.
5V/div.
V
V
OUT
OUT
2V/div.
2V/div.
I
L
I
L
1A/div.
1A/div.
1ms/div.
MP1423-TPC03
MP1423-TPC04
PIN FUNCTIONS
Pin # Name Description
High-Side Gate Drive Bootstrap Input. BS supplies the drive for the high-side N-Channel
MOSFET switch. Connect a 4.7nF or greater capacitor from SW to BS to power the high side
switch.
Power Input. IN supplies the power to the IC, as well as the step-down converter switches.
Drive IN with a 6V to 23V power source. Bypass IN to GND with a suitably large capacitor to
eliminate noise on the input to the IC. See Input Capacitor
1
2
BS
IN
Power Switching Output. SW is the switching node that supplies power to the output. Connect
the output LC filter from SW to the output load. Note that a capacitor is required from SW to BS
to power the high-side switch.
3
4
5
SW
GND Ground. (Note: For the SOIC8N package, connect the exposed pad on backside to Pin 4).
Feedback Input. FB senses the output voltage to regulate said voltage. Drive FB with a
resistive voltage divider from the output voltage. The feedback threshold is 1.222V. See
FB
Setting the Output Voltage
MP1423 Rev. 1.1
1/6/2006
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3
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