MP8904 –500mA LINEAR REGULATOR

MP8904 Rev. 1.02

www.MonolithicPower.com

8

6/6/2012

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© 2012 MPS. All Rights Reserved.

APPLICATION INFORMATION

Setting the Output Voltage

The MP8904 has an adjustable output voltage

set via an external resistor divider (R1 and R2

in Figure 2).



















FB

FB

OUT

V

V

V

2

R

1

R

threshold voltage.

Example: For a 2.5V output and R2=10kΩ

k

40

5

.

0

5

.

0

5

.

2

k

10

1

R





















Use a standard 40kΩ (

1%) resistor for R1.

Table 1 lists selected R1 values for typical

output voltages (R2 = 10kΩ).

Power-Good

The power-good (PG) pin monitors the output

voltage; if the output voltage goes below 10% of

its regulation point, the PG pin goes low. The

PG pin is an open collector output that connects

to a pull-up resistor (typically 10kΩ). Tie the

pull-up resistor to 0V-to-5.5V supply, such as

regulated input voltage.

Table 1: Adjustable Output Voltage Values vs. R1

(R2 =10kΩ)

R1 (Ω)

1.25

15k

1.5

20k

1.8

26k

2

30k

2.5

40k

2.8

46k

3

50k

3.3

56k

4

70k

5

90k

Bypass Capacitors

Bypass the reference voltage can be bypassed

with an external capacitor to reduce noise. Use

a low-ESR ceramic capacitor for the best

performance.

TYPICAL APPLICATION CIRCUIT

MP8904

OUT

FB

GND

8

5

3

1

4

6

IN

EN

PG

1.8V

C3

1nF

PG

Figure 2: Typical Application Circuit