Micrel, Inc.

MIC2103/04

August 2012

3

M9999-080712-A

Pin Description (Continued)

Pin Number

Pin Name

Pin Function

9, 11

NC

No connection.

10

BST

Voltage Supply Pin input for the high-side N-channel MOSFET driver, which can be powered by a

bootstrapped circuit connected between VDD and SW, using a Schottky diode and a 0.1μF

ceramic capacitor. Adding a small resistor at BST pin can slow down the turn-on speed of the

high-side MOSFET.

12

AGND

Signal ground for VDD and the control circuitry, which is connected to Thermal Pad electronically.

The signal ground return path should be separate from the power ground (PGND) return path.

13

FB

Feedback input. Input to the transconductance amplifier of the control loop. The FB pin is

regulated to 0.8V. A resistor divider connecting the feedback to the output is used to set the

desired output voltage.

14

PG

Power Good output. Open Drain Output, an external pull-up resistor to VDD or external power

rails is required.

15

EN

Enable input. A logic signal to enable or disable the buck converter operation. The EN pin is

CMOS compatible. Logic high enables the device, logic low shutdowns the regulator. In the

16

VIN

Supply voltage. The VIN operating voltage range is from 4.5V to 75V. A 1μF ceramic capacitor

from VIN to AGND is required for decoupling.

EP

ePad

Exposed Pad. Connect the EPAD to PGND plain on the PCB to improve the thermal

performance.