Micrel, Inc.

MIC2238

July 2007

2

M9999-071307

Ordering Information

Part Number

Lead Finish

Junction

Temperature

Range

Package

MIC2238-AAYML

Adjustable

Adjustable

Pb-Free

–40

°C to +125°C

3 × 3 MLF-12L

Fixed output options available. Contact Micrel Marketing for further details.

Pin Configuration

MIC2238-xxYML

12-Lead MLF

(Top View)

Pin Description

Pin Number

Adjustable

Pin Number

Fixed

Pin Name

Pin Name

1

-

FB2

Feedback 2: For adjustable voltage options connect the

external resistor divider network to FB2 to set the output

voltage of regulator 2. Nominal value is 0.8V.

2

2

EN2

Enable 2 input. Logic low powers down regulator 2. Logic

high powers up regulator 2. MIC2238 features built-in soft-

start circuitry that reduces in-rush current and prevents the

output voltage from overshooting at start up.

3

3

AVIN

Analog Supply Voltage: Supply voltage for the analog control

circuitry. Requires bypass capacitor to GND.

4

4

SW2

Switch node for regulator 2, connected to external inductor.

5

5

AGND

Analog (signal) ground.

6

6

PGND

Power ground.

7

7

/FPWM

Forced PWM Mode Bar. Grounding this pin forces the device

to stay in constant frequency PWM mode only. Pulling this

pin high enables automatic Trickle mode operation.

8

8

SW1

Switch node for regulator 1, connected to external inductor.

9

9

VIN

Supply Voltage: Supply voltage for the internal switches and

drivers.

10

10

PGOOD

Power Good Output. This output is pulled down unless the

regulator 1 output voltage is within +6.25% and -8.5% of

regulation. After the output voltage is in regulation, the output

starts to go high with an internal 5µA current source. A delay

time could be programmed by tying a capacitor to this pin.