MP8904 –500mA LINEAR REGULATOR
MP8904 Rev. 1.02 www.MonolithicPower.com 8
6/6/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 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
FBOUT
V
VV
2R1R
where V
FB
= 0.5V is the OUT feedback
threshold voltage.
Example: For a 2.5V output and R2=10k
k40
5.0
5.05.2
k101R
Use a standard 40k (1%) resistor for R1.
Table 1 lists selected R1 values for typical
output voltages (R2 = 10k).
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 10k). 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)
V
OUT
(V) 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
V
IN
PG
Figure 2: Typical Application Circuit
