MP1586 – 3A, 28V, 50kHz TO 400kHz STEP-DOWN CONVERTER
BLOCK DIAGRAM
V
VIN
IN
+
--
+
--
5V
2.6V
REFERENCE UVLO/
INTERNAL
REGULATORS
EN
THERMAL
SHUTDOWN
BST
SW
SW
--
+
I
SW
1.5ms SS
SS
V
OUT
I
Level
Shift
SW
FB
Gm Error Amp
--
+
COMP
SS
0V8
OSCILLATOR
CLK
V
OUT
FREQ
GND
COMP
Figure 1—Function Block Diagram
OPERATION
The MP1586 is a non-synchronous, step-down
switching regulator with an integrated high-side
high voltage power MOSFET. It provides a
highly efficient solution with current mode
control for fast loop response and easy
compensation. It features a wide input voltage
range, internal soft-start control and precision
current limiting. Its very low operational
quiescent current makes it suitable for battery
powered applications.
PWM Control
At moderate to high output current, the MP1586
operates in a fixed frequency, peak current
control mode to regulate the output voltage. A
PWM cycle is initiated by the internal clock. The
power MOSFET is turned on and remains on
until its current reaches the value set by the
COMP voltage. When the power switch is off, it
remains off for at least 100ns before the next
cycle starts. If, in one PWM period, the current
in the power MOSFET does not reach the
COMP set current value, the power MOSFET
remains on, saving a turn-off operation.
MP1586 Rev. 0.91
1/8/2010
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