Datasheet

MAX8860
Low-Dropout, 300mA
Linear Regulator in µMAX
6 _______________________________________________________________________________________
Internal P-Channel Pass Transistor
The MAX8860 features a 0.5Ω typical P-channel
MOSFET pass transistor. This provides several advan-
tages over similar designs using PNP pass transistors,
including longer battery life. PNP-based regulators
waste considerable amounts of current in dropout when
the pass transistor saturates. They also use high base-
drive currents under large loads. The P-channel
MOSFET requires no base-drive current, which reduces
quiescent current considerably. The MAX8860 con-
sumes less than 165µA of quiescent current whether in
dropout, light-load, or heavy-load applications (see the
Typical Operating Characteristics).
Output Voltage Selection
The MAX8860 features Dual Mode operation: it operates
in either a preset voltage mode or an adjustable mode.
In preset voltage mode, internal, trimmed feedback
resistors set the output voltage to an adjustable 1.25V to
6.5V output voltage or a fixed-voltage output of 1.8V
(MAX8860EUA18), 2.5V (MAX8860EUA25), 2.77V
(MAX8860EUA27), 2.82V (MAX8860EUA28), 3V
(MAX8860EUA30), or 3.3V (MAX8860EUA33). Select
this mode by connecting SET to ground. In adjustable
mode, select an output between 1.25V and 6.5V using
two external resistors connected as a voltage divider to
SET (Figure 2). Calculate the output voltage with the fol-
lowing equation:
where V
SET
= 1.25V. To simplify resistor selection, use
the following equation:
R1 R2
V
V
1
OUT
SET
=−






VV
R
R
OUT SET
=+






1
1
2
SHUTDOWN
LOGIC
ERROR
AMP
1.25V
REF
P
OUT
CC
SET
FAULT
DUAL-MODE
COMPARATOR
60mV
GND
IN
SHDN
MAX8860
THERMAL
SENSOR
FAULT
DETECT
REVERSE
BATTERY
PROTECTION
MOS DRIVER
WITH I
LIMIT
Figure 1. Functional Diagram
Figure 2. Adjustable Output Using External Feedback
Resistors
MAX8860
OUT
SET
FAULT
GND
IN
SHDN
CC
C
OUT
2.2µF
C
IN
2.2µF
33nF
BATTERY
OUTPUT
VOLTAGE
R1
R2
100kΩ