MIC2177

Micrel

MIC2177

2

April 1999

Ordering Information

Part

Output

Switching

Temperature

Number

Voltage

Frequency

Range

Package

MIC2177-3.3BWM

3.3V

200kHz

–40

°C to +85°C

20-lead wide SOP

MIC2177-5.0BWM

5.0V

200kHz

–40

°C to +85°C

20-lead wide SOP

MIC2177BWM

adj.

200kHz

–40

°C to +85°C

20-lead wide SOP

Pin Description

Pin Number

Pin Name

Pin Function

1, 2, 9

VIN

Supply Input: Controller and switch supply. Unregulated supply input to

internal regulator, output switches, and control circuitry. Requires bypass

capacitor to PGND. All three pins must be connected to V

3,8

SW

Switch (Output): Internal power MOSFET switch output. Both pins must be

externally connected together.

4,5,6,7

PGND

Power Ground: Output stage ground connections. Connect all pins to a

common ground plane.

10

OUT

Output Voltage Sense (Input): Senses output voltage to determine minimum

switch current for PWM operation. Connect directly to V

11

AUTO

Automatic Mode: Connect 2.2nF timing capacitor for automatic PWM-/skip-

mode switching. Regulator operates exclusively in PWM mode when pin is

pulled low.

12

FB

Feedback (Input): Error amplifier inverting input. For adjustable output

version, connect FB to external resistive divider to set output voltage. For

3.3V and 5V fixed output versions, connect FB directly to output.

13

COMP

Compensation: Internal error amplifier output. Connect to capacitor or series

RC network to compensate the regulator control loop.

14,15,16,17

SGND

Signal Ground: Ground connection of control section. Connect all pins to

common ground plane.

18

SYNC

Frequency Synchronization (Input): Optional clock input. Connect to

external clock signal to synchronize oscillator. Leading edge of signal above

1.7V terminates switching cycle. Connect to SGND if not used.

19

BIAS

Bias Supply: Internal 3.3V bias supply output. Decouple with 0.01

µF

bypass capacitor to SGND. Do not apply any external load.

20

EN

Enable (Input): Logic high enables operation. Logic low shuts down

regulator. Do not allow pin to float.

Pin Configuration

2

VIN

3

SW

4

PGND

5

PGND

6

PGND

7

PGND

1

VIN

8

SW

9

VIN

EN

20

BIAS

19

SYNC

18

SGND

17

SGND

16

SGND

15

10

OUT

14

13

12

11 AUTO

FB

COMP

SGND

20-Lead Wide SOP