stability and optimum transient response. Surface-mount
ceramic capacitors have very low ESR and are com-
monly available in values up to 10µF. Connect C
IN
and
C
OUT
as close to the MAX8887/MAX8888 as possible to
minimize the impact of PC board trace inductance.
Noise, PSRR, and Transient Response
The MAX8887/MAX8888 are designed to operate with
low dropout voltages and low quiescent currents in bat-
tery-powered systems while still maintaining excellent
noise, transient response, and AC rejection. See the
Typical Operating Characteristics
for a plot of power-
supply rejection ratio (PSRR) versus frequency. When
operating from noisy sources, improved supply-noise
rejection and transient response can be achieved by
increasing the values of the input and output bypass
capacitors and through passive filtering techniques.
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differen-
tial (dropout voltage) determines the lowest usable sup-
ply voltage at which the output is regulated. In
battery-powered systems, this determines the useful
end-of-life battery voltage. The MAX8887/MAX8888 use
a p-channel MOSFET pass transistor. Its dropout volt-
age is a function of drain-to-source on-resistance
(R
DS(ON)
) multiplied by the load current (see the
Typical Operating Characteristics
).
V
DROPOUT
= V
IN
- V
OUT
= R
DS(ON)
✕
I
OUT
MAX8887/MAX8888
Low-Dropout, 300mA Linear Regulators in SOT23
_______________________________________________________________________________________ 7
vs. INPUT VOLTAGE
