MAX8887 Datasheet, PDF (7/8 Pages) Maxim Integrated Products – Low-Dropout, 300mA Linear Regulators in SOT23

Low-Dropout, 300mA Linear Regulators in SOT23
IN
SHDN
MAX8888
SHUTDOWN
LOGIC
ERROR
AMP
MOS DRIVER
WITH I_LIMIT
P
OUT
POK
THERMAL
1.25V
95%
POK
SENSOR
REF
REF
GND
Figure 1. Functional Diagram
put capacitors with an ESR of 0.1Ω or less to ensure sta-
bility 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
MAXIMUM OUTPUT CURRENT
vs. INPUT VOLTAGE
(POWER DISSIPATION LIMIT)
400
T_A = +85°C
T_A = +70°C
300 ^{MAXIMUM RECOMMENDED OUTPUT CURRENT}
200
100
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
(V_IN - V_OUT) (V)
Figure 2. Power Operating Regions: Maximum Output Current
vs. Input Voltage
Chip Information
TRANSISTOR COUNT: 620
PROCESS: BiCMOS
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