MAX8881EUT33-T [MAXIM]
12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK; 12V ，超低IQ，低压差线性稳压器，带有POK
| 型号： | MAX8881EUT33-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 12V, Ultra-Low-IQ, Low-Dropout Linear Regulators with POK |
| 文件： | 总8页 (文件大小：229K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1679; Rev 0; 4/00
12V, Ultra-Low-I , Low-Dropout
Q
Linear Regulators with POK
General Description
Features
The MAX8880/MAX8881 are ultra-low supply current,
low-dropout linear regulators, capable of delivering up
to 200mA. They are designed for battery-powered
applications where reverse battery protection and long
battery life are critical.
ꢀ 3.5µA Supply Current at 12V
ꢀ Reverse Battery Protection
ꢀ 2.5V to 12V Input Voltage Range
ꢀ
1.5ꢀ ꢁutput Voltage Accuracy
These regulators’ low 3.5µA supply current extends
battery life in applications with long standby periods.
Unlike PNP-based designs, a 2Ω PMOS device main-
tains ultra-low supply current throughout the entire
operating range and in dropout. The parts are internally
protected from output short circuits, reverse battery
connection, and thermal overload. An internal power-
OK (POK) comparator indicates when the output is out
of regulation.
ꢀ 200mA max ꢁutput Current
ꢀ 2Ω PMꢁS ꢁutput Device
ꢀ Short-Circuit and Thermal ꢁverload Protection
ꢀ PꢁK ꢁutput for ꢁut-of-Regulation Indicator
ꢀ Fixed 1.8V, 2.5V, 3.3V, and 5V (MAX8881)
Adjustable from 1.25V to 5V (MAX8880)
The MAX8880 output is adjustable from 1.25V to 5V
using an external resistor-divider. The MAX8881 pro-
vides only factory-preset output voltages of 1.8V, 2.5V,
3.3V, or 5V (see Ordering Information). Both devices
are available in miniature 6-pin SOT23 packages.
ꢀ Tiny 6-Pin SꢁT23 Package
________________________Applications
Smoke Detectors
PDAs
Handy Terminals
Battery-Powered Alarms
Remote Transmitters
Smart Battery Packs
CMOS Backup Power
Real-Time Clocks
Typical Operating Circuit
Pin Configuration
V
OUT
1.25V TO 5V
V
IN
TOP VIEW
IN
OUT
FB
2.5V TO 12V
UP TO 200mA
4.7µF
1µF
IN
GND
OUT
1
2
3
6
5
4
POK
SHDN
FB
MAX8881
MAX8880
MAX8881
REGULATION OK
ON
SHDN
POK
OFF
GND
SꢁT23-6
Ordering Information
PART
ꢁUTPUT
Adjustable
1.8V
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
6 SOT23-6
TꢁP MARK
AAHR
MAX8880EUT-T
MAX8881EUT18-T
MAX8881EUT25-T
MAX8881EUT33-T
MAX8881EUT50-T
AAHS
2.5V
AAHT
3.3V
AAHU
5.0V
AAHV
________________________________________________________________ Maxim Integrated Products
1
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
12V, Ultra-Low-I , Low-Dropout
Q
Linear Regulators with POK
ABSꢁLUTE MAXIMUM RATINGS
IN to GND................................................................-14V to +14V
OUT Continuous Current...................................................200mA
OUT Short Circuit...........................................................Indefinite
SHDN to GND.............................................-0.3V to (V + 0.3V),
IN
Continuous Power Dissipation (T = +70°C)
-0.3V to +0.3V when V < 0V
A
IN
6-Pin SOT23 (derate 8.7mW/°C above +70°C)...........696mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature.........................................-65°C to +165°C
Lead Temperature (soldering, 10s) .................................+300°C
OUT, FB to GND...............................-0.3V to +6V when V > 5.7V,
IN
-0.3V to (V + 0.3V) when 0V ≤ V ≤ 5.7V,
IN
IN
-0.3V to +0.3V when V < 0V
IN
POK to GND ...........................................................-0.3V to +14V
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V = V
+ 1V, SHDN = IN, C = 4.7µF, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
OUT A A
IN
OUT
PARAMETER
SYMBꢁL
CꢁNDITIꢁNS
MIN
TYP
MAX
12
UNITS
Input Voltage Range
Supply Current
V
2.5
V
µA
µA
V
IN
IN
I
V
V
= 12V
3.5
1.5
10
IN
Shutdown Supply Current
Input Undervoltage Lockout
I
= 0, V = 12V, V
= 0, T = +25°C
3
IN(SHDN)
SHDN
IN
OUT
A
V
2.1
2.4
UVLO
T = +25°C
1.238
1.232
1.219
-1.5
-2
1.257
1.276
1.282
1.295
1.5
A
FB Voltage, Adjustable
Mode
MAX8880,
= 20mA
V
T = 0°C to +85°C
A
V
FB
I
OUT
T = -40°C to +85°C
A
T = +25°C
A
OUT Voltage Accuracy
(Note 2)
MAX8881,
= 20mA
T = 0°C to +85°C
A
2
%
I
OUT
T = -40°C to +85°C
A
-3
3
OUT Voltage Range
V
MAX8880
1.25
5.5
V
%/V
%/mA
mA
OUT
OUT Line Regulation
V
= V
+ 1V to 12V
OUT
0.01
0.006
400
0.05
0.015
IN
OUT Load Regulation (Note 3)
Current Limit (Note 3)
I
= 10µA to 100mA
OUT
I
200
2
OUT
Dropout Voltage (Notes 3, 4)
IN Reverse Leakage Current
Foldback Current Limit
∆V
DO
IN(REV)
I
= 50mA
100
200
1
mV
OUT
I
V
V
= -12V, V
= 0
SHDN
mA
IN
IN
I
= 5V, V
= 0
OUT
250
mA
OUT(SC)
V
IH
SHDN Input Threshold
V
= 2.5V to 12V
V
IN
V
0.5
100
20
IL
SHDN Input Bias Current
FB Input Bias Current
V
= 0 to 12V, T = +25°C
-100
0
nA
nA
SHDN
A
I
FB = 1.25V, T = +25°C, MAX8880 only
2
FB
A
Falling
T
= +25°C
87.5
86
90.5
93.5
95
A
% of
T
A
= -40°C to +85°C
POK Trip Threshold
V
OUT
Hysteresis
1.5
50
POK Off-Current
POK Low Voltage
I
V
= 12V, T = +25°C
100
200
nA
POK
POK
POK
A
V
I
= 1mA
mV
POK
2
_______________________________________________________________________________________
12V, Ultra-Low-I , Low-Dropout
Q
Linear Regulators with POK
ELECTRICAL CHARACTERISTICS (continued)
(V = V
+ 1V, SHDN = IN, C
= 4.7µF, T = -40°C to +85°C, unless otherwise noted. Typical values are at T = +25°C.) (Note 1)
A A
IN
OUT
OUT
PARAMETER
SYMBꢁL
CꢁNDITIꢁNS
(Hysteresis = 15°C)
f = 10Hz to 100kHz, I
MIN
TYP
160
300
MAX
UNITS
Thermal Shutdown Threshold
OUT Noise
T
°C
TSD
OUT(NOISE)
V
= 1mA
µV
RMS
OUT
Note 1: All devices are 100% production tested at T = +25°C. All temperature limits are guaranteed by design.
A
Note 2: Output accuracy with respect to nominal preset voltages. FB = OUT.
Note 3: This specification is valid for V > 3V.
IN
Note 4: The dropout voltage is defined as V - V
, when V
is 100mV below the value of V
for V = V
+ 1V.
IN
OUT
OUT
OUT
IN
OUT
Typical Operating Characteristics
(V = 5V, V
IN
= 3.3V, I
= 30mA, C
= 4.7µF, T = +25°C, unless otherwise noted. See Figure 1.)
OUT
OUT
OUT
A
DROPOUT VOLTAGE
vs. LOAD CURRENT
SUPPLY CURRENT
vs. TEMPERATURE
SUPPLY CURRENT
vs. INPUT VOLTAGE
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
500
450
400
350
300
250
200
150
100
50
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
V
= 1.8V
OUT
I
= 30 mA
OUT
T
A
= +85°C
NO LOAD
T
A
= +25°C
T
A
= -40°C
0
0
0
-40
-15
10
35
60
85
0
50
100
150
200
2
4
6
8
10
12
TEMPERATURE (°C)
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
OUTPUT NOISE SPECTRAL DENSITY
vs. FREQUENCY
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
OUTPUT NOISE
vs. LOAD CURRENT
70
10
1
400
350
300
250
200
150
100
50
C
= 1.0µF
OUT
60
50
40
30
20
10
0
C
OUT
= 4.7µF
0.10
0.01
V
OUT
= 1.8V
20
0
0.1
1
10
100
1k
10k
10
100
1k
10k
100k
0
40
60
80
100
FREQUENCY (Hz)
LOAD CURRENT (mA)
FREQUENCY (Hz)
_______________________________________________________________________________________
3
12V, Ultra-Low-I , Low-Dropout
Q
Linear Regulators with POK
Typical Operating Characteristics (continued)
(V = 5V, V
IN
= 3.3V, I
= 30mA, C
= 4.7µF, T = +25°C, unless otherwise noted. See Figure 1.)
OUT
OUT
OUT
A
SUPPLY CURRENT
vs. LOAD CURRENT
OUTPUT VOLTAGE ERROR
vs. LOAD CURRENT
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
3.8
3.7
3.6
3.5
3.4
3.3
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
0
0
50
100
150
200
0
2
4
6
8
10
12
14
50
100
150
200
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
CHANGE FROM NOMINAL OUTPUT
VOLTAGE vs. TEMPERATURE
REGION OF STABLE C
ESR
OUT
vs. OUTPUT CURRENT
LINE-TRANSIENT RESPONSE
MAX8880/1-12
100
0.20
0.15
0.10
0.05
0
9.75V
9V
10
1
C
= 10µF
C
OUT
-0.05
-0.10
-0.15
-0.20
= 4.7µF
OUT
STABLE REGION
0.1
100
150
200
-40
-15
10
35
60
85
0
50
200µs/div
= V , 500mV/div, AC COUPLED
TEMPERATURE (°C)
OUTPUT CURRENT (mA)
C
C
H1
H2
IN
= V , 20mV/div, AC COUPLED
OUT
V
= 5V, I = 5mA
OUT
OUT
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
LOAD-TRANSIENT RESPONSE
TURN-ON RESPONSE
MAX8880/1-14
MAX8880/1-13
MAX8880/1-15
32.5mA
1.25mA
32.5mA
1.25mA
4V
1.8V
400µs/div
= I , 12.5mA/div
400µs/div
= I , 12.5mA/div
100µs/div
C
C
V
C
C
C
V
= SHDN, 2V/div
OUT
= 4.0V
H1 OUT
H1 OUT
= V , 100mV/div, AC COUPLED
H1
H2
IN
= V , 100mV/div, AC COUPLED
C
H2
V
= V , 1V/div
H2
OUT
OUT
= 5.2V, V
= 5V
= 5V, V = 9V
IN
OUT(NOMINAL)
OUT(NOMINAL)
IN
4
_______________________________________________________________________________________
12V, Ultra-Low-I , Low-Dropout
Q
Linear Regulators with POK
Pin Description
PIN
NAME
FUNCTIꢁN
1
IN
Input Voltage. Bypass with a 1µF capacitor to GND.
2
3
GND
OUT
Ground
Output Voltage. Bypass with a 4.7µF capacitor (<0.5Ω ESR) to GND for load currents up to
200mA. For load currents up to 40mA, 1µF is acceptable.
Feedback Set Point, 1.25V (MAX8880 only). Output sense, connect to OUT externally
(MAX8881EUT_ _ only).
4
5
6
FB
ON/OFF Control. Regulator is ON when V
> 2V. If unused, connect to IN. If reverse
SHDN
SHDN
POK
battery protection of the SHDN input is desired, connect a 100kΩ resistor in series with SHDN.
POK Output, Open Drain. Low when OUT is out of regulation or in shutdown. Connect POK to
IN through a high-value resistor for a simple error indicator.
than the reference voltage, the pass-transistor gate is
Detailed Description
pulled lower, allowing more current to pass, 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 out-
put. The output voltage is fed back through either an
internal resistor voltage divider by externally connect-
ing FB to OUT (MAX8881EUT_ _), or an external resis-
tor network connected to FB (MAX8880). Additional
blocks include an output current limiter, reverse battery
protection, a thermal sensor, shutdown logic, and a
POK comparator to indicate when the output is out of
regulation (Figure 2).
The MAX8880/MAX8881 are low-dropout, low-quies-
cent current linear regulators designed primarily for
battery-powered applications (Figure 1). The MAX8880
provides an adjustable output voltage from 1.25V to 5V
using an external resistor-divider. The MAX8881 is
available in factory preset output voltages of 1.8V, 2.5V,
3.3V, and 5V. Both devices have a +1.25V reference,
error amplifier, MOSFET driver, and P-channel pass
transistor (Figure 2).
Low-Dropout Regulator
The 1.25V reference is connected to the error amplifi-
er’s inverting input. The error amplifier compares this
reference with 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
Internal P-Channel Pass Transistor
The MAX8880/MAX8881 feature a 2Ω P-channel MOS-
FET pass transistor. This provides advantages over
similar designs using PNP pass transistors, including
longer battery life. The P-channel MOSFET requires no
base drive, which reduces quiescent current consider-
ably. PNP-based regulators waste considerable current
in dropout when the pass transistor saturates. They
also use high base-drive currents under large loads.
The MAX8880/MAX8881 do not suffer from these prob-
lems and consume only 3.5µA of supply current (see
Typical Operating Characteristics).
V
IN
VOUT
2.5V TO 12V
IN
OUT
FB
C2
4.7µF
C1
1µF
R2*
100k
MAX8881
Dropout Voltage
A regulator’s minimum input-output differential (or
dropout voltage) determines the lowest usable supply
voltage. In battery-powered systems, this determines
the useful end-of-life battery voltage. Because the
MAX8880/MAX8881 use a P-channel MOSFET pass
REGULATION OK
SHDN
POK
GND
transistor, their dropout voltage is R
(2Ω) multi-
DS(ON)
plied by the load current (see Electrical Characteristics).
*OPTIONAL
Figure 1. Standard Application Circuit
_______________________________________________________________________________________
5
12V, Ultra-Low-I , Low-Dropout
Q
Linear Regulators with POK
REVERSE
BATTERY
PROTECTION
IN
SHDN
P
MOS DRIVER
WITH I
LIMIT
ERROR
AMP
OUT
FB
SHUTDOWN
LOGIC
MAX8881
POK
POK
1.25V
REF
91%
REF
THERMAL
SENSOR
GND
Figure 2. Functional Diagram
Current Limiting
The MAX8880/MAX8881 include a current limiter. When
the output is shorted to ground, drive to the output
PMOS is limited. The output can be shorted to ground
without damage to the part.
V
IN
V
OUT
1.25V TO 5.5V
2.5V TO 12V
IN
UP TO 200mA
OUT
C1
C2
R3
R4
1µF
4.7µF
Thermal Overload Protection
Thermal overload protection limits total power dissipa-
tion in the MAX8880/MAX8881. When the internal junc-
MAX8880
FB
tion temperature exceeds T = +160°C, the thermal
J
REGULATION OK
SHDN
sensor signals the shutdown logic, turning off the pass
transistor and allowing the IC to cool. The thermal sen-
sor turns the pass transistor on again after the IC’s
junction temperature cools by 15°C, resulting in a
pulsed output during continuous thermal-overload con-
ditions.
POK
GND
Thermal-overload protection is designed to protect the
MAX8880/MAX8881 in the event of fault conditions. For
continuous operation, do not exceed the absolute maxi-
Figure 3. Adjustable Output Using External Feedback Resistors
Reverse Battery Protection
The MAX8880/MAX8881 have a unique protection
scheme that limits the reverse supply current to less
mum junction temperature rating of T
= +150°C.
J(MAX)
Operating Region and Power Dissipation
The MAX8880/MAX8881’s maximum power dissipation
depends on the thermal resistance of the case and cir-
cuit board, the temperature difference between the die
junction and ambient air, and the rate of airflow. The
than 1mA when V is forced below ground. The circuit
IN
monitors the polarity of IN, disconnecting the internal
circuitry and parasitic diodes when the battery is
reversed. This feature prevents the device from electri-
cal stress and damage when the battery is connected
backwards. If reverse battery protection is needed,
drive SHDN through a 100kΩ resistor.
power dissipation in the device is P = I
OUT
(V
-
IN
OUT
V
). The maximum power dissipation allowed is:
6
_______________________________________________________________________________________
12V, Ultra-Low-I , Low-Dropout
Q
Linear Regulators with POK
output to 5V. Connect the MAX8881’s FB to OUT for
T
− T
A
(
)
J(MAX)
proper operation.
P
=
MAX
θ
(
+ θ
CA
)
JC
The MAX8880 features an adjustable output voltage
from 1.25V to 5.5V, using two external resistors con-
nected as a voltage-divider to FB (Figure 3).
where T
= +150°C, T is the ambient tempera-
A
J(MAX)
ture, θ is the thermal resistance from the junction to
JC
The output voltage is set by the following equation:
the case (115°C/W), and θ
is the thermal resistance
CA
from the case through the PC board, copper traces,
and other materials to the surrounding air.
R3
R4
V
= V 1 +
FB
OUT
POK Output
The open-drain POK output is useful as a simple error
flag, as well as a delayed reset output. POK sinks cur-
rent when the output voltage is 10% below the regula-
tion point. Connect POK to OUT through a high-value
resistor for a simple error flag indicator. Connect a
capacitor in parallel with the resistor to produce a
delayed POK signal (delay set by the RC time con-
stant). POK is low during out of regulation or in shut-
down and is high impedance during normal operation.
where typically V = 1.257V. Choose R4 = 1.2MΩ to
FB
optimize quiescent current, accuracy, and high-fre-
quency power-supply rejection. To simplify resistor
selection:
V
V
OUT
R3 = R4
−1
FB
The total current through the external resistive feedback
and load resistors should be greater than 1µA. Since the
V
tolerance is typically less than 1.5%, the output
FB
Applications Information
can be set using fixed resistors instead of trim pots.
Capacitor Selection and Regulator
Stability
Power-Supply Rejection and Operation
from Sources Other than Batteries
The MAX8880/MAX8881 are designed to be stable with
an output filter capacitor as low as 1µF and an ESR as
high as 1Ω. For general purposes, use a 1µF capacitor
on the device’s input and a 4.7µF capacitor on the out-
put. Larger input capacitor values and lower ESR pro-
vide better supply-noise rejection and transient
response. Use a higher value input capacitor (10µF may
be necessary) if large, fast transients are anticipated
and the device is located several inches from the power
source. Use large output capacitors to improve load-
transient response, stability, and power-supply rejec-
tion. Note that some ceramic dielectric materials (e.g.,
Z5U and Y5V) exhibit a large temperature coefficient for
both capacitance and ESR, and a larger output capaci-
tance may be needed to ensure stability at low tempera-
tures. A 4.7µF output capacitor with X7R or X5R
dielectrics should be sufficient for stable operation over
the full temperature range, with load currents up to
200mA. For load currents up to 40mA, 1µF is accept-
The MAX8880/MAX8881 are designed to deliver low-
dropout voltages and low quiescent currents in battery-
powered systems. Power-supply rejection is -66dB at
low frequencies and rolls off with frequencies above
100Hz. At high frequencies, the output capacitor is the
major contributor to the rejection of power-supply noise
(see Power-Supply Rejection Ratio vs. Frequency in the
Typical Operating Characteristics).
When operating from sources other than batteries,
improve supply-noise rejection and transient response
by increasing the value of the input and output capaci-
tors and by using passive filtering techniques.
The MAX8880/MAX8881 load-transient response
graphs (see Typical Operating Characteristics) show
the output response due to changing load current.
Reduce overshoot by increasing the output capacitor’s
value up to 10µF and by reducing its ESR.
able. A graph of the Region of Stable C
ESR vs.
out
Output Current is shown in the Typical Operating
Characteristics.
Chip Information
TRANSISTOR COUNT: 134
Output Voltage Selection
The MAX8881 features a preset output voltage. Internal
precision feedback resistors set the MAX8881EUT18 out-
put to 1.8V, the MAX8881EUT25 output to 2.5V, the
MAX8881EUT33 output to 3.3V, and the MAX8881EUT50
_______________________________________________________________________________________
7
12V, Ultra-Low-I , Low-Dropout
Q
Linear Regulators with POK
Package Information
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2000 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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