max8877euk39t Maxim Integrated Products, Inc., max8877euk39t Datasheet - Page 6

• Manufacturer Part Number: max8877euk39t
• Description: Low-noise, Low-dropout, 150ma Linear Regulators With 2982 Pinout
• Manufacturer: Maxim Integrated Products, Inc.

The MAX8877/MAX8878 are low-noise, low-dropout,
low-quiescent-current linear regulators designed pri-
marily for battery-powered applications. The parts are
available with preset output voltages ranging from 1.5V
to 5V, in 100mV increments. These devices can supply
loads up to 150mA. As illustrated in Figure 1, the
MAX8877/MAX8878 consist of a 1.25V reference, error
amplifier, P-channel pass transistor, and internal feed-
back 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
Low-Noise, Low-Dropout, 150mA Linear
Regulators with '2982 Pinout
Figure 1. Functional Diagram
6
_______________Detailed Description
______________________________________________________________Pin Description
_______________________________________________________________________________________
PIN
1
2
3
4
5
* AUTO-DISCHARGE, MAX8878 ONLY
SHDN
GND
MAX8878
MAX8877
IN
NAME
SHDN
GND
OUT
PROTECTION
BP
IN
REVERSE
BATTERY
Regulator Input. Supply voltage can range from 2.5V to 6.5V. Bypass with a 1µF capacitor to GND
(see Capacitor Selection and Regulator Stability section).
Ground. This pin also functions as a heatsink. Solder to a large pad or the circuit-board ground
plane to maximize power dissipation.
Active-Low Shutdown Input. A logic low reduces the supply current to 10nA. On the MAX8878, a
logic low also causes the output voltage to discharge to GND. Connect to IN for normal operation.
Reference-Noise Bypass. Bypass with a low-leakage, 0.01µF ceramic capacitor for reduced noise at
the output.
Regulator Output. Sources up to 150mA. Bypass with a 1µF (<0.2Ω typical ESR) capacitor to GND
for V
OUT
≥ 2.5V and 3.3µF for V
SHUTDOWN
POWER-ON
CONTROL
THERMAL
SENSOR
AND
1.25V
REF
OUT
< 2.5V.
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 is fed back through an internal resistor voltage
divider connected to the OUT pin.
An external bypass capacitor connected to the BP pin
reduces noise at the output. Additional blocks include a
current limiter, reverse battery protection, thermal sen-
sor, and shutdown logic. The MAX8878 also includes
an auto-discharge function, which actively discharges
the output voltage to ground when the device is placed
in shutdown mode.
ERROR
AMP
FUNCTION
MOS DRIVER
WITH I
LIMIT
*
N
P
OUT
BP