MP2324 – 24V, 2A SYNC STEP-DOWN CONVERTER
PIN FUNCTIONS
Package
Pin #
Name Description
Power Good Output. The output of this pin is an open drain. It’s pulled up to Vcc by
external resistor when the output voltage exceeds 90% of the normal voltage. There is a
1
PG
IN
40μs delay between FB≥90% to the PG pin goes high.
Supply Voltage. The IN pin supplies power for internal MOSFET and regulator. The
MP2324 operates from a +4.5V to +24V input rail. Requires a low-ESR, and low
inductance capacitor (C1) to decouple the input rail. Place the input capacitor very close to
this pin and connect it with wide PCB traces and multiple vias.
2
Switch Output. Connect to the inductor and bootstrap capacitor. This pin is driven up to
VIN by the high-side switch during the PWM duty cycle ON time. The inductor current
drives the SW pin negative during the OFF time. The ON resistance of the low-side switch
and the internal body diode fixes the negative voltage. Connect using wide PCB traces and
multiple vias.
3
4
SW
System Ground. This pin is the reference ground of the regulated output voltage.
For this reason care must be taken in PCB layout. Suggested to be connected to GND with
copper and vias.
GND
Bootstrap. A capacitor and a 20Ω resistor connected between SW and BST pins are
required to form a floating supply across the high-side switch driver.
5
6
7
BST
EN/SYNC
VCC
EN=1 to enable the MP2324. External clock can be applied to EN pin for changing
switching frequency. For automatic start-up, connect EN pin to VIN with a 100kΩ resistor.
Bias Supply. Decouple with 0.1μF-0.22μF cap. And the capacitance should be no more
than 0.22μF
Feedback. An external resistor divider from the output to GND, tapped to the FB pin, sets
the output voltage. To prevent current limit run away during a short circuit fault condition
the frequency fold-back comparator lowers the oscillator frequency when the FB voltage is
below 400mV.
8
FB
MP2324 Rev. 1.0
12/4/2013
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