TM
MP2305 – 2A, 23V SYNCHRONOUS RECTIFIED, STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS (continued)
VIN = 12V, TA = +25°C, unless otherwise noted.
Parameter
Symbol Condition
Min
Typ
Max
Units
Input Under Voltage Lockout
Threshold
VIN Rising
3.80
4.10
4.40
V
Input Under Voltage Lockout
Threshold Hysteresis
210
mV
Soft-Start Current
Soft-Start Period
VSS = 0V
CSS = 0.1µF
6
15
160
µA
ms
°C
Thermal Shutdown (4)
Note:
4) Guaranteed by design, not tested.
PIN FUNCTIONS
Pin # Name Description
High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET
switch. Connect a 0.01µF or greater capacitor from SW to BS to power the high side switch.
1
2
BS
IN
Power Input. IN supplies the power to the IC, as well as the step-down converter switches.
Drive IN with a 4.75V 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.
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.
Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a
resistive voltage divider from the output voltage. The feedback threshold is 0.923V. See
FB
Setting the Output Voltage.
Compensation Node. COMP is used to compensate the regulation control loop. Connect a
series RC network from COMP to GND to compensate the regulation control loop. In some
cases, an additional capacitor from COMP to GND is required. See Compensation
Components.
6
COMP
Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on
the regulator, drive it low to turn it off. Pull up with 100kΩ resistor for automatic startup.
7
8
EN
SS
Soft-Start Control Input. SS controls the soft start period. Connect a capacitor from SS to GND
to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 15ms. To disable the
soft-start feature, leave SS unconnected.
MP2305 Rev. 1.7
4/17/2006
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3
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