Micrel, Inc.

MIC23050

January 2010

8

M9999-012010-D

Functional Description

VIN

VIN provides power to the MOSFETs for the switch mode

regulator section and to the analog supply circuitry. Due to

the high switching speeds, it is recommended that a 2.2µF

or greater capacitor be placed close to VIN and the power

ground (PGND) pin for bypassing. Refer to the layout

recommendations for details.

EN

The enable pin (EN) controls the on and off state of the

device. A logic high on the enable pin activates the

regulator, while a logic low deactivates it. MIC23050

features built-in soft-start circuitry that reduces in-rush

current and prevents the output voltage from overshooting

at start up. Do not leave this pin floating.

SW

The switch (SW) pin connects directly to the inductor and

provides the switching current necessary to operate in

PWM mode. Due to the high speed switching on this pin,

the switch node should be routed away from sensitive

nodes such as the CFF pin.

SNS

An inductor is connected from the SW pin to the SNS pin.

The SNS pin is the output pin of the device and a minimum

of 2.2µF bypass capacitor should be connected in shunt.

In order to reduce parasitic inductance it is good practice

to place the output bypass capacitor as close to the

inductor as possible.

CFF

The CFF pin is connected to the SNS pin of MIC23050

with a feed-forward capacitor of 560pF. The CFF pin itself

the device and provides the control path to control the

noise and should be place away from the SW pin. Refer to

the layout recommendations for details.

PGND

Power ground (PGND) is the ground path for the high

current PWM mode. The current loop for the power ground

should be as small as possible and separate from the

Analog ground (AGND) loop. Refer to the layout

recommendations for more details.

AGND

Signal ground (AGND) is the ground path for the biasing

and control circuitry. The current loop for the signal ground

should be separate from the Power ground (PGND) loop.

Refer to the layout recommendations for more details.