Micrel, Inc.

MIC26601

July 2011

3

M9999-071311-A

Pin Description (Continued)

Pin Number

Pin Name

Pin Function

22

CS

Current Sense (Input): The CS pin senses current by monitoring the voltage across the low-side

MOSFET during the OFF-time. The current sensing is necessary for short circuit protection. In order

to sense the current accurately, connect the low-side MOSFET drain to SW using a Kelvin

connection. The CS pin is also the high-side MOSFET’s output driver return.

23

SGND

Signal ground. SGND must be connected directly to the ground planes. Do not route the SGND pin to

the PGND Pad on the top layer (see PCB Layout Guidelines for details).

24

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 adjust the desired output

voltage.

25

PG

Power Good (Output): Open Drain Output. The PG pin is externally tied with a resistor to VDD. A high

26

EN

Enable (Input): A logic level control of the output. The EN pin is CMOS-compatible. Logic high =

enable, logic low = shutdown. In the off state, supply current of the device is greatly reduced (typically

5µA). The EN pin should not be left open.

27

VIN

Power Supply Voltage (Input): Requires bypass capacitor to SGND.

28

VDD

5V Internal Linear Regulator (Output): VDD supply is the power MOSFET gate drive supply voltage

should be tied to PVIN pins. A 1.0µF ceramic capacitor from the VDD pin to PGND pins must be place

next to the IC.