MP3421—5.5A, 600KHZ HIGH EFFICIENCY, SYNCHRONOUS, STEP-UP CONVERTER WITH OUTPUT DISCONNECT IN 2X2MM QFN PACKAGE
MP3421 Rev. 1.0 www.MonolithicPower.com 9
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PIN FUNCTIONS
Pin # Name Pin Function
1, 2, 13 PGND Power Ground.
3, 14 SW
Power-Switch Output. SW is the internal NMOS switch and synchronous switch connection
node . Connect the power inductor between SW and input power. Keep these PCB trace
lengths as short and wide as possible to reduce EMI and voltage spikes.
4, 5, 6 OUT
Output. OUT is the internal synchronous rectifier MOSFET drain. Bias is derived from OUT
when V
OUT
is higher than V
IN
. PCB trace length from OUT to the output filter capacitor(s)
should be as short and wide as possible. Due to the output disconnect feature, OUT is
completely disconnected from IN when EN is low.
7 NC No Connect. Reserved for factory use only. Float or connect NC to GND in the application.
8 EN Enable Control Input.
9 IN
Power-Supply Input. The startup bias is derived from IN. It must be locally bypassed. Once
OUT exceeds IN, bias comes from OUT. Once started, operation is completely independent
from IN.
10 INA Power-Supply Input (for factory use only). INA must be connected to IN in the application.
11 AGND Analog Signal Ground.
12 FB
Feedback Input to Error Amplifier. Connect resistor divider tap to FB. The output voltage
can be adjusted from 2.5V to 5.5V
