MP8801

– 150MA, LOW-NOISE, LOW-DROPOUT LINEAR REGULATOR

MP8801 Rev. 2.0

MonolithicPower.com

8

7/19/2021

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© 2021 MPS. All Rights Reserved.

APPLICATION INFORMATION

Setting the Output Voltage

The MP8801

’s fixed output voltage (VOUT) can

be set to 2.5V, 2.85V, or 3.3V, depending on

the internal resistor divider. The fixed output

can be converted to an adjustable output via an

external resistor divider (R1 + R2). To minimize

the impact of the internal resistor divider, the

sum of R1 and R2 should be below 100kΩ. For

an accurate VOUT setting, use a 10kΩ (±1%)

resistor for the low-side resistor (R2). Then the

high-side resistor (R1) can be calculated with

Equation (1):



















FB

FB

OUT

V

V

V

2

R

1

R

(1)

Where VFB is the output feedback voltage

threshold (1.222V).

For example, if VOUT is 2.5V, then R1 can be

calculated with Equation (2):























k

41

.

10

k

10

V

222

.

1

V

222

.

1

V

5

.

2

1

R

(2)

S

elect a standard 10.5kΩ (

1%) resistor for R1.

Table 1 lists the selected R1 values for typical

output voltages.

Table 1: R1 Values for Adjustable VOUT

VOUT (V)

R1 (Ω)

R2 (Ω)

1.25

232

Ω

10k

Ω

1.5

2.26k

Ω

1.8

4.75k

Ω

2

6.34k

Ω

2.5

10.5k

Ω

2.8

13k

Ω

3

14.7k

Ω

3.3

16.9k

Ω

4

22.6k

Ω

5

30.9k

Ω

A capacitor (C2) can be added for improved

transient response (see Figure 3 and Figure 4

on page 9).

Selecting the Input Capacitor

For stable operation, choose a 1µF to 10µF

ceramic capacitor (C1) with X5R or X7R

dielectrics. Place C1 between the IN pin and

ground. A larger-value capacitor improves line

transient response; however, a larger-value

capacitor also has a larger physical size.

Selecting the Output Capacitor

For stable operation, choose a 1µF to 10µF

ceramic capacitor (C3) with X5R or X7R

dielectrics. A larger-value capacitor improves

load transient response and reduces noise;

however, a larger-value capacitor also has a

larger physical size. Output capacitors with

other dielectric types may be used, but are not

recommended as their capacitance can deviate

from the rated value over temperature.

To improve load transient response, add a

small ceramic (X5R, X7R, or Y5V dielectric)

100nF feed-forward capacitor in parallel with R1.

This

capacitor

is

not

required

for

stable

operation.