MIC2178

Micrel

MIC2178

2

June 1998

Pin Description

Pin Number

Pin Name

Pin Function

1, 2, 9

VIN

Supply Voltage (Input): Requires bypass capacitor to PGND. All three pins

must be connected to V

3, 8

SW

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

be externally connected together.

4, 5, 6, 7

PGND

Power Ground: Connect all pins to central ground point.

10

PWM

PWM/Skip-Mode Control (Input): Logic-level input. Controls regulator

operating mode. Logic low enables PWM mode. Logic high enables skip

mode. Do not allow pin to float.

11

PWRGD

Error Flag (Output): Open-drain output. Active low when FB input is 10%

below the reference voltage (V

12

FB

Feedback (Input): Connect to output voltage divider resistors.

13

COMP

Compensation: Output of internal error amplifier. Connect capacitor or

series RC network to compensate the regulator control loop.

14, 15, 16, 17

SGND

Signal Ground: Connect all pins to ground, PGND*.

18

SYNC

Frequency Synchronization (Input): Optional. Connect an external clock

signal to synchronize the oscillator. Leading edge of signal above 1.7V

terminates switching cycle. Connect to SGND if not used.

19

BIAS

Internal 3.3V Bias Supply: 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

PWM

14

13

12

11 PWRGD

FB

COMP

SGND

20-Lead Wide Power SOIC

Ordering Information

Part Number

Voltage

Temperature Range

Package

MIC2178BWM

Adjustable

–40

°C to +85°C

20-lead Wide SOIC

MIC2178-3.3BWM

3.3V

–40

°C to +85°C

20-lead Wide SOIC

MIC2178-5.0BWM

5.0V

–40

°C to +85°C

20-lead Wide SOIC