6

Date: 5/25/04

SPX2810 1A Low Dropout Linear Regulator

© Copyright 2004 Sipex Corporation

Figure 11. 12.5V Regulator with Shutdown

Figure 10. Improving Ripple Rejection

Figure 12. Recommended Connections for Best Results

Output Voltage

The output of the adjustable regulator can be set to any voltage between 1.25V and 10V. The value

of V

V

A small correction to this formula is required depending on the values of resistors R1 and R2, since

adjustable pin current (approx 50

µA) flows through R2. When I

becomes

V

Layout Considerations

Parasitic line resistance can degrade load regulation. In order not to affect the behavior of the regulator,

it is best to connect R

connected to the negative side of the load.

SPX2810

V

IN

Connect R

2

to Load

Case of Regulator

Resistance

V

OUT

ADJ

SPX2810

V

IN

10µF

1k

Ω

1%

330Ω

1%

+

+

4.7µF

5V

ADJ

IN

OUT

(Note A)

1k

1k

TTL

Input

2N3904

DROPOUT (MAX)

Note A: V

IN(MIN)

= (Intended V

OUT

) + (V

)

SPX2810

V

IN

R

1

R

2

10µF

10µF*

1kΩ,

330Ω

1%

+

+

4.7µF

C

1

*C

1

improves ripple rejection.

Z

C

should be ~ R1 at ripple frequency

5V

ADJ

IN

OUT

(Note A)

V

OUT

Note A: V

1%