August 2005

3

MIC5156/5157/5158

MIC5156/5157/5158

Micrel, Inc.

Pin Description MIC5156

Pin Number

Pin Name

Pin Function

1

EN

Enable (Input): TTL high enables regulator; TTL low shuts down regulator.

2

FLAG

than 8% below nominal output. Circuit has 3% hysteresis.

3

GND

Circuit ground.

4

N-channel Gate Drive Supply Voltage: User supplied voltage for driving the

gate of the external MOSFET.

5

Supply Voltage (Input): Supply voltage connection. Connect sense resis-

ground near device.

6

G

Gate (Output): Drives the gate of the external MOSFET.

7

D

Drain and Current Limit (Input): Connect to external MOSFET drain and ex-

drain (no current limit).

8 (3.3V, 5V)

S

Source (Input): Top of internal resistive divider chain. Connect directly to the

load for best load regulation.

8 (adjustable)

EA

Error Amplifier (Input): Connect to external resistive divider.

Pin Description MIC5157, MIC5158

Pin Number

Pin Name

Pin Function

1 (MIC5157)

5V

5V Configuration (Input): Connect to S (source) pin for 5V output.

1 (MIC5158)

EA

Error Amplifier (Input): Connect to external resistive divider to obtain adjust-

able output.

2 (MIC5157)

3.3V

3.3V Configuration (Input): Connect to S (source) pin for 3.3V output.

2 (MIC5158)

5VFB

5V Feedback (Input): Connect to EA for fixed 5V output.

3

FLAG

or more below its nominal value.

4

GND

Circuit ground.

5

Voltage Tripler Output [Filter Capacitor]. Connect a 1 to 10µF capacitor to ground.

6

C2–

Charge Pump Capacitor 2: Second stage of internal voltage tripler. Connect a

0.1µF capacitor from C2+ to C2–.

7

C2+

Charge Pump Capacitor 2: See C2– pin 6.

8

C1+

Charge Pump Capacitor 1: First stage of internal voltage tripler. Connect a

0.1µF capacitor from C1+ to C1–.

9

C1–

Charge Pump Capacitor 1: See C1+ pin 8.

10

Supply Voltage (Input): Supply voltage connection. Connect sense resis-

ground near device.

11

G

Gate (Output): Connect to External MOSFET gate.

12

D

Drain and Current Limit (Input): Connect to external MOSFET drain and ex-

drain (no current limit).

13 (MIC5157)

S

Source and 3.3V/5V Configuration: Top of internal resistor chain. Connect to

source of external MOSFET for 3.3V, 5V, and 12V operation. Also see 3.3V

and 5V pin descriptions.

13 (MIC5158)

S

Source (Input): Top of internal resistor chain. Connect to top of external resis-

tive divider and source of external MOSFET.

14

EN

Enable (Input): TTL high enables regulator; TTL low shuts down regulator.