Advanced Monolithic Systems, Inc.

6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140

LP2950/LP2951

APPLICATION HINTS (Continued)

OUTPUT

VOLTAGE

ERROR*

INPUT

VOLTAGE

4.75V

5V

1.3V

R

1

ERROR*

ERROR

OUPUT

**SHUTDOWN

INPUT

GND

FB

V

OUT

V

REF

R

2

SD

1.23V

7

4

3

8

1

5

+V

IN

+V

IN

V

OUT

1.2

30V

3.3

µF

.01

µF

+

*

100k

LP2951

FIGURE 1. ERROR Output Timing

FIGURE 2. Adjustable Regulator

as the pull-up voltage (see Figure 2), rather than an external 5V

source, will keep the error flag voltage under 1.2V (typ.) in this

condition. The user may wish to drive down the error flag

voltage using equal value resistors (10 k

suggested), to ensure

a low-level logic signal during any fault condition, while still

allowing a valid high logic level during normal operation.

*See Application Hints.

× (1 + R

**Drive with TTL- high to shut down. Ground or leave if shutdown

feature is not used.

Note: Pins 2 and 6 are left open.

TYPICAL APPLICATIONS

300 mA Regulator with 0.75 Dropout

Wide Input Voltage Range Current Limiter

UNREGULATED

INPUT

LOAD

50mA TO

300mA

GND

FB

OUT

IN

4

7

6

2

1

8

V

TAP

LP2951

2N5432 (2)

SENSE

5V OUTPUT

4.7µF

27kΩ

330Ω

ERROR

ERROR

OUPUT

SHUTDOWN

INPUT

GND

FB

V

OUT

SD

7

4

3

8

1

5

+V

IN

+V

IN

LP2951

*V

ΙΝ

*Minimum Input-Output voltage ranges from 40mV to 400mV, depending on load

current. Current limit is typically 160 mA