MAX8875 데이터 시트보기 (PDF) - Maxim Integrated
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MAX8875 Datasheet PDF : 9 Pages
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150mA, Low-Dropout Linear Regulator
with Power-OK Output
Pin Description
PIN NAME
FUNCTION
1
IN
Regulator Input. Supply voltage can range from 2.5V to 6.5V. Bypass with 1µF to GND (see the Capacitor
Selection and Regulator Stability section).
2
GND
Ground. This pin also functions as a heatsink. Solder to a large pad or the circuit-board ground plane to
maximize power dissipation.
3
SHDN
Active-Low Shutdown Input. A logic low reduces the supply current to below 1µA. Connect to IN for normal
operation.
4
POK
Power-OK Output. Active-low, open-drain output indicates an out-of-regulation condition. Connect a 100k
pull-up resistor to OUT for logic levels. If not used, leave this pin unconnected.
Regulator Output. Fixed 5.0V, 3.3V, 3.0V, 2.7V, 2.5V, or 1.5V output. Sources up to 150mA. Bypass with 1µF
5
OUT
(<0.2Ω typical ESR) ceramic capacitor to GND for VOUT ≥ 2.5V. Bypass with 3.3µF (<0.2Ω typ ESR) ceramic
capacitor to GND for VOUT = 1.5V.
IN
SHDN
REVERSE-
BATTERY
PROTECTION
MAX8875
SHUTDOWN
LOGIC
ERROR
AMP
MOS DRIVER
WITH ILIMIT
P
OUT
POK
THERMAL
1.25V
95%
POK
SENSOR
REF
REF
GND
Figure 1. Functional Diagram
_______________Detailed Description
The MAX8875 is a low-dropout, low-quiescent-current
linear regulator designed primarily for battery-powered
applications. The device supplies loads up to 150mA
and is available with preset output voltages of 1.5V,
2.5V, 2.7V, 3.0V, 3.3V, or 5.0V. As illustrated in Figure
1, the MAX8875 consists of a 1.25V reference, error
amplifier, P-channel pass transistor, power-OK com-
parator, and internal feedback voltage divider.
The 1.25V bandgap reference is connected to the error
amplifier’s inverting input. The error amplifier compares
this reference with the feedback voltage and amplifies
the difference. If the feedback voltage is lower than the
reference voltage, the pass-transistor gate is pulled
lower, which allows more current to pass to the output
and increases the output voltage. If the feedback volt-
age is too high, the pass-transistor gate is pulled up,
allowing less current to pass to the output. The output
voltage feeds back through an internal resistor voltage
divider connected to the OUT pin.
Additional blocks include a current limiter, reverse-
battery protection, thermal sensor, and shutdown logic.
6 _______________________________________________________________________________________
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