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MAX8860EUA18+

P1-P3P4-P6P7-P8
MAX8860
Low-Dropout, 300mA
Linear Regulator in µMAX
4 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(V
IN
= V
OUT
+ 0.5V, C
IN
= C
OUT
= 2.2µF, C
CC
= 33nF, T
A
= +25°C, unless otherwise noted.)
0
60
40
20
100
80
180
160
140
120
200
0123456
NO LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX8860 toc04
INPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
20
60
40
120
100
80
160
0
140
180
0 10050 150 200 250 300
DROPOUT VOLTAGE vs. LOAD CURRENT
MAX8860 toc05
LOAD CURRENT (mA)
DROPOUT VOLTAGE (mV)
T
A
= +85°C
T
A
= +25°C
T
A
= -40°C
0
50
150
100
200
250
0 10050 150 200 250 300
FAULT DETECT THRESHOLD
vs. LOAD CURRENT
MAX8860 toc06
LOAD CURRENT (mA)
FAULT DETECT THRESHOLD (mV)
FAULT = HIGH
FAULT = LOW
-70
-50
-60
-30
-40
-10
-20
0
0.01 10.1 10 100 1000
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX8860 toc07
FREQUENCY (kHz)
PSRR (dB)
200mA
I
LOAD
0
LOAD-TRANSIENT RESPONSE
MAX8860 toc10
400µs/div
V
OUT
20mV/div
V
IN
= V
OUT
+ 200mV
0.1 101 100 1000
OUTPUT NOISE SPECTRAL DENSITY
MAX8860 toc08
FREQUENCY (kHz)
NOISE (µV/√Hz)
0.01
0.1
1.0
10
C
OUT
= 2.2µF
C
OUT
= 10µF
I
LOAD
= 10mA
V
OUT
500µV/div
OUTPUT NOISE
(10Hz TO 1MHz)
MAX8860 toc09
1ms/div
I
LOAD
= 200mA
+4.3V
LINE-TRANSIENT RESPONSE
MAX8860 toc12
500µs/div
V
OUT
2mV/div
V
IN
+3.3V
I
LOAD
= 200mA
MAX8860
Low-Dropout, 300mA
Linear Regulator in µMAX
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(V
IN
= V
OUT
+ 0.5V, C
IN
= C
OUT
= 2.2µF, C
CC
= 33nF, T
A
= +25°C, unless otherwise noted.)
NAME FUNCTION
1, 4 OUT Regulator Output. Bypass with 2.2µF, low-ESR capacitor to GND for stable operation.
PIN
Pin Description
4V
2V
0
4V
3V
2V
1V
0
POWER-UP RESPONSE
MAX8860 toc13
5ms/div
FAULT
V
OUT
V
IN
4V
2V
0
4V
3V
2V
1V
0
POWER-DOWN RESPONSE
MAX8860 toc14
2ms/div
V
OUT
V
IN
FAULT
4V
2V
0
3V
2V
1V
0
SHUTDOWN/POWER-UP
MAX8860 toc15
400µs/div
V
OUT
SHDN
2 IN Supply Input. Connect to power source (2.5V to 6.5V). Bypass with 2.2µF capacitor to GND.
3 GND Ground
5 SET
Output Voltage Set. Connect to GND for internally set threshold. Connect to resistor-divider for adjustable
output voltages. See the Output Voltage Selection section for more information.
6 CC Compensation Capacitor. Connect a 0.033µF capacitor from CC to GND.
7
SHDN Shutdown Input. Connect to IN for normal operation. Drive SHDN low to turn off the regulator.
8
FAULT
Fault Output. A high-impedance, open-drain output. When the MAX8860 is out of regulation, FAULT goes
low. In shutdown, the FAULT pin is high impedance. Connect to GND if unused.
Detailed Description
The MAX8860 is a low-dropout, low-quiescent-current
linear regulator designed primarily for battery-powered
applications. It supplies 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), 3.0V
(MAX8860EUA30), or 3.3V (MAX8860EUA33) for load
currents up to 300mA. The devices with 2.77V and
2.82V nominal outputs are designed to guarantee mini-
mum output voltages of 2.70V and 2.75V, respectively.
The device consists of a 1.25V reference, error amplifi-
er, MOSFET driver, P-channel pass transistor, Dual
Mode comparator, fault detector, and internal-feedback
voltage divider (Figure 1).
The 1.25V bandgap reference is connected to the error
amplifier’s inverting input. The error amplifier compares
this reference to the selected feedback voltage and
amplifies the difference. The MOSFET driver reads the
error signal and applies the appropriate drive to the P-
channel pass transistor. If the feedback voltage is lower
than the reference voltage, the pass-transistor gate is
pulled lower, allowing more current to pass and
increasing the output voltage. If the feedback voltage
is higher than the reference voltage, the pass-transistor
gate is driven higher, allowing less current to pass to
the output. The output voltage is fed back through
either an internal resistor voltage divider connected to
OUT, or an external resistor network connected to SET.
The Dual Mode comparator examines V
SET
and selects
the feedback path. If V
SET
is below 60mV, internal
feedback is used and the output voltage is regulated to
the preset output voltage. Additional blocks include an
output current limiter, reverse battery protection, a ther-
mal sensor, a fault detector, and shutdown logic.
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
P1-P3P4-P6P7-P8

MAX8860EUA18+

Mfr. #:
Buy MAX8860EUA18+
Manufacturer:
Maxim Integrated
Description:
LDO Voltage Regulators 300mA Linear Regulator
Lifecycle:
New from this manufacturer.
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