TM
MP28372 — DUAL 1.5A, 23V, 1.4MHz STEP-DOWN CONVERTER
PIN FUNCTIONS (SOIC16)
Pin #
Name Description
Soft-Start Control for Channel A. 9kꢀ output resistance from the pin. Set RC time constant
with external capacitor for soft start ramp time. Ramp Time = 2.2 x 9kꢀ x C.
1
2
3
SSA
BSA
INA
High-Side Driver Boost Pin. Connect a 10nF capacitor from this pin to SWA.
Supply Voltage Channel A. The MP28372 operates from a +4.75V to +23V unregulated input.
Input Ceramic Capacitors should be close to this pin.
4
5
SWA
Switch Channel A. This connects the inductor to either INA through M1A or to PGA through M2A.
GNDA Ground A.
Feedback Voltage for Channel B. This pin is the feedback voltage. The output voltage is ratio scaled
6
7
FBB
through a voltage divider, and the center point of the divider is connected to this pin. The voltage is
compared to the on board 0.92V reference.
Compensation Channel B. This is the output of the transconductance error amplifier. A series
COMPB RC is placed on this pin for proper control loop compensation. Please refer to more in the
datasheet.
Enable/UVLO Channel B. A voltage greater than 2.62V enables operation. Leave ENB
unconnected for automatic startup. An Under Voltage Lockout (UVLO) function can be
implemented by the addition of a resistor divider from VIN to GND. For complete low current
8
ENB
shutdown the ENB pin voltage needs to be less than 700mV.
Soft-Start Control for Channel B. 9kꢀ output resistance from the pin. Set RC time constant
with external capacitor for soft start ramp time. Ramp Time = 2.2x9kꢀxC.
9
SSB
10
11
BSB
INB
High-Side Driver Boost Pin. Connect a 10nF capacitor from this pin to SWB.
Supply Voltage Channel B. The MP28372 operates from a +4.75V to +23V unregulated input.
Input Ceramic Capacitors should be close to this pin.
12
13
SWB
Switch Channel B. This connects the inductor to either INB through M1B or to PGB through M2B.
GNDB Ground B.
Feedback Voltage for Channel A. This pin is the feedback voltage. The output voltage is ratio scaled
14
15
FBA
through a voltage divider, and the center point of the divider is connected to this pin. The voltage is
compared to the on board 0.92V reference.
Compensation Channel A. This is the output of the transconductance error amplifier. A series
COMPA RC is placed on this pin for proper control loop compensation. Please refer to more in the
datasheet.
Enable/UVLO Channel A. A voltage greater than 2.62V enables operation. Leave ENA
unconnected for automatic startup. An Under Voltage Lockout (UVLO) function can be
implemented by the addition of a resistor divider from VIN to GND. For complete low current
16
ENA
shutdown the ENA pin voltage needs to be less than 700mV.
MP28372 Rev. 1.4
12/10/2007
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5
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