MP8802 – LOW DROPOUT, 250mA LINEAR REGULATOR

MP8802 Rev. 1.3

www.MonolithicPower.com

5

3/6/2006

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© 2006 MPS. All Rights Reserved.

APPLICATION INFORMATION

SETTING THE OUTPUT VOLTAGE

The fixed output voltage of the MP8802DJ is set

to 2.5V, 2.85V or 3.3V, depending on the

internal resistor divider (Figure 1). You can also

adjust the output voltage by using an external

resistor divider (R1 and R2 in Figure 2).

However, the sum of R1 and R2 should not

exceed 100kΩ to minimize the impact of the

internal resistor divider. For accurate output-

voltage setting, it is suggested to use 10kΩ

(

±1%) for the low-side resistor R2 of the voltage

divider, the high side resistor R1 can be

determined by the equation:

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

×

=

FB

FB

OUT

V

V

V

2

R

1

R

voltage equal to 1.222V.

Example: For 2.5V Output

Ω

=

⎟

⎠

⎞

⎜

⎝

⎛

Ω

−

=

k

41

.

10

k

10

V

222

.

1

V

222

.

1

V

5

.

2

1

R

You can select a standard 10.5kΩ (

±1%)

resistor for R1.

The following table lists the selected R1 values

for some typical output voltages:

Table 1—Adjustable Output Voltage R1 Values

R1 (Ω)

1.25

232

1.5

2.26k

1.8

4.75k

2

6.34k

2.5

10.5k

2.8

13k

3

14.7k

3.3

16.9k

4

22.6k

5

30.9k

In Figures 3 and 4, C2 is added for an improved

transient response.