MP4459 – 1.5A, 4MHz, 36V STEP-DOWN CONVERTER
MP4459 Rev. 1.03 www.MonolithicPower.com 4
4/9/2014 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2014 MPS. All Rights Reserved.
PIN FUNCTIONS
Pin # Name Description
1, 2 SW
Switch Node. This is the output from the high-side switch. A low V
f
Schottky rectifier to ground
is required. The rectifier must be close to the SW pins to reduce switching spikes.
3 EN
Enable Input. Pulling this pin below the specified threshold shuts the chip down. Pulling it up
above the specified threshold or leaving it floating enables the chip.
4 COMP
Compensation. This node is the output of the GM error amplifier. Control loop frequency
compensation is applied to this pin.
5 FB
Feedback. This is the input to the error amplifier. An external resistive divider connected
between the output and GND is compared to the internal +0.8V reference to set the regulation
voltage.
6 GND
Ground. It should be connected as close as possible to the output capacitor avoiding the high
current switch paths.
7 FREQ
Switching Frequency Program Input. Connect a resistor from this pin to ground to set the
switching frequency.
8, 9 VIN
Input Supply. This supplies power to all the internal control circuitry, both BS regulators and
the high-side switch. A decoupling capacitor to ground must e placed close to this pin to
minimize switching spikes.
10 BST
Bootstrap. This is the positive power supply for the internal floating high-side MOSFET driver.
Connect a bypass capacitor between this pin and SW pin.
