MAX1725EUK-T [MAXIM]
12V, Ultra-Low IQ, Low-Dropout Linear Regulators; 12V ，超低IQ，低压差线性稳压器
| 型号： | MAX1725EUK-T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 12V, Ultra-Low IQ, Low-Dropout Linear Regulators |
| 文件： | 总7页 (文件大小：153K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-1680; Rev 1; 2/03
12V, Ultra-Low I , Low-Dropout
Q
Linear Regulators
General Description
Features
The MAX1725/MAX1726 are ultra-low supply current,
low-dropout linear regulators intended for low-power
applications that demand the longest possible battery
life. Unlike inferior PNP-based designs, the MAX1725/
MAX1726s’ PMOS pass elements maintain an ultra-low
2µA supply current throughout their entire operating
range and in dropout. Despite their ultra-low power
consumption, the MAX1725/MAX1726 have tight output
accuracy (1.5%) and require just 1µF output capacitance
to achieve good load-transient response.
ꢀ 2µA Supply Current
ꢀ Reverse-Battery Protection
ꢀ +2.5V to +12V Input Voltage Range
ꢀ Fixed 1.8V, 2.5V, 3.3V, and 5V Output Voltages
(MAX1726)
ꢀ Adjustable 1.5V to 5V Output Voltages (MAX1725)
ꢀ 20mA Guaranteed Output Current
ꢀ 1.5% Output Voltage Accuracy
ꢀ Small 1µF Output Capacitor
ꢀ Short-Circuit Protection
These regulators have a wide input voltage range
(+2.5V to +12V), making them excellent choices for
systems powered from two lithium-ion (Li+) cells and 9V
batteries. Other features include reverse-battery protec-
tion, short-circuit protection, and thermal protection.
ꢀ Thermal Protection
The MAX1725 provides an adjustable 1.5V to 5V output
using an external resistor-divider. The MAX1726 pro-
vides factory preset 1.8V, 2.5V, 3.3V, or 5V output volt-
ages (see the Ordering Information). Both devices are
available in a tiny 5-pin SOT23 package.
ꢀ Tiny 5-Pin SOT23 Package
Ordering Information
________________________Applications
Smoke Detectors
PIN-
PACKAGE
TOP
MARK
PART
TEMP RANGE
Remote Transmitters
MAX1725EUK-T
-40°C to +85°C
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
5 SOT23-5
ADNK
ADNL
ADNM
ADNN
ADNO
Smart Battery Packs
MAX1726EUK18-T -40°C to +85°C
MAX1726EUK25-T -40°C to +85°C
MAX1726EUK33-T -40°C to +85°C
Industrial Control Systems
Microcontroller Power
Real-Time Clock Backup Power
PDAs and Handy-Terminals
Battery-Powered Alarms
MAX1726EUK5-T
-40°C to +85°C
Note: See the Selector Guide for the MAX1725/MAX1726 output
options as they relate to the part number suffix.
Typical Operating Circuit
Selector Guide
OUTPUT VOLTAGE
PART
(V)
V
OUTPUT
1.5V TO 5V
IN
IN
OUT
2.5V TO 12V
MAX1725EUK-T
MAX1726EUK18-T
MAX1726EUK25-T
MAX1726EUK33-T
MAX1726EUK50-T
Adj 1.5 to 5.0
Fixed 1.8
Fixed 2.5
Fixed 3.3
Fixed 5.0
MAX1726
ON
SHDN
GND
OFF
Pin Configuration appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
12V, Ultra-Low I , Low-Dropout
Q
Linear Regulators
ABSOLUTE MAXIMUM RATINGS
IN to GND................................................................-14V to +14V
OUT Short Circuit...........................................................Indefinite
SHDN to GND..............................................-0.3V to (V + 0.3V)
Continuous Power Dissipation (T = +70°C)
5-Pin SOT23-5 (derate 7.1mW/°C above +70°C) ........571mW
IN
A
(-0.3V to + 0.3V when V < 0V)
IN
OUT, FB (MAX1725 only) to GND...................-0.3V to +6V when
θ
...............................................................................+140°C/W
JA
V
>5.7V; -0.3V to (V + 0.3V) when 0V <
Junction Temperature......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
IN
IN
V
IN
< 5.7V; -0.3V to +0.3V when V < 0V
IN
OUT Continuous Current...................................................200mA
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
(Circuit of Figure 1, V = V
+ 1V, SHDN = IN, I
= 1mA, T = -40°C to +85°C, unless otherwise noted. Typical values are at
OUT A
IN
OUT
T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
12
4.5
2
UNITS
Input Voltage Range
Supply Current
V
IN
(Note 2)
= 12V
2.5
V
µA
µA
V
I
V
IN
2
IN
IN(SHDN)
Shutdown Supply Current
OUT Voltage Range
FB Voltage
I
0.7
SHDN = 0V, V = 12V, V
= 0V
OUT
IN
V
OUT
MAX1725 only
1.5
5
V
FB
MAX1725 only (Note 3)
1.245
V
T
T
T
= +25°C
-1.5
-2
1.5
+2
+3
0.3
A
A
A
OUT Voltage Accuracy (Note 3)
= 0°C to +85°C
= -40°C to +85°C
%
-3
Line Regulation
∆V
∆V
V
= 2.5V or (V + 0.5V) to 12V
OUT
0.01
0.015
80
%/V
%/mA
mA
LNR
IN
I
= 1mA to 20mA, V = (V + 1V)
OUT
OUT
IN
Load Regulation
0.15
LDR
or 3V (min)
Maximum OUT Current
Dropout Voltage (Note 4)
Foldback Current Limit
SHDN Input Threshold
I
V
= (V + 1V) or 3V (Note 4)
OUT
20
OUT
IN
I
= 20mA for V
≥ 2.5V, I = 10mA for
OUT
OUT
OUT
∆V
300
40
600
mV
DO
V
< 2.5V, not applicable for V
< 1.9V
OUT
OUT
I
V
= 12V, V = 0V
OUT
mA
SC
IN
IN
V
2
IH
V
V
= 2.5V to 12V
= 0V to 12V
V
V
0.5
IL
T
T
T
T
= +25°C
= +85°C
= +25°C
= +85°C
-50
-20
+50
A
A
A
A
I
nA
nA
SHDN Input Bias Current
SHDN
SHDN
0.1
2
+20
10
FB Input Bias Current
(MAX1725 only)
I
FB
V
V
= 1.25V
FB
1.5
0.01
150
15
IN Reverse Leakage Current
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
= -12V, V
= 0V
µA
°C
°C
IN
SHDN
Temperature rising
2
_______________________________________________________________________________________
12V, Ultra-Low I , Low-Dropout
Q
Linear Regulators
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V = V
+ 1V, SHDN = IN, I
= 1mA, T = -40°C to +85°C, unless otherwise noted. Typical values are at
A
IN
OUT
OUT
T
A
= +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
0.25V, t = t = 5µs
MIN
TYP
MAX
UNITS
OUT Line-Transient
Overshoot/Undershoot
∆V
=
15
mV
IN
R
F
OUT Load-Transient
Overshoot/Undershoot
I
from 1mA to 10mA, t = t = 1µs
200
350
mV
OUT
R
F
OUT Noise
e
n
f = 10Hz to 100kHz
µV
RMS
Note 1: Limits are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 2: Guaranteed by OUT line-regulation testing.
Note 3: OUT accuracy from nominal voltage. The MAX1725 is tested at V
= 1.5V, 2.5V, and 5V.
OUT
Note 4: When V
falls to 4% below its value at V = V
+ 1V.
OUT
IN
OUT
Typical Operating Characteristics
(V
= +3.3V, I
= 1mA, T = +25°C, unless otherwise noted.)
A
OUT
OUT
SUPPLY CURRENT vs. TEMPERATURE
SUPPLY CURRENT vs. LOAD CURRENT
SUPPLY CURRENT vs. INPUT VOLTAGE
5
4
3
2
1
0
5
4
3
2
1
0
5
4
3
2
1
0
V
= 5V
V
= 5V
IN
IN
-40
-20
0
20
40
60
80
4
5
6
7
8
9
10 11 12
0
5
10
15
20
TEMPERATURE (°C)
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
NORMALIZED OUTPUT VOLTAGE
vs. TEMPERATURE
OUTPUT VOLTAGE vs. LOAD CURRENT
OUTPUT VOLTAGE vs. INPUT VOLTAGE
0
-0.2
-0.4
-0.6
-0.8
0.8
0.6
0.4
0.2
0
0.30
0.20
0.10
0
NOMINAL OUTPUT = 3.3V
NOMINAL OUTPUT = 3.3V
V
= 4.5V
IN
I
= 1mA
LOAD
I
= 1mA
OUT
-0.2
-0.10
-0.20
-0.30
-1.0
-1.2
-0.4
-0.6
-0.8
I
= 20mA
9
LOAD
8
-1.4
0
2
4
6
8
10 12 14 16 18 20
4
5
6
7
10 11 12
-40
-20
0
20
40
60
80
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
TEMPERATURE (°C)
_______________________________________________________________________________________
3
12V, Ultra-Low I , Low-Dropout
Q
Linear Regulators
Typical Operating Characteristics (continued)
= 1mA, T = +25°C, unless otherwise noted.)
OUT A
(V
= +3.3V, I
OUT
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
DROPOUT VOLTAGE vs. LOAD CURRENT
LINE-TRANSIENT RESPONSE
80
70
60
50
40
30
20
10
0
300
C
OUT
= 1µF
V
V
L
= 5V
OUT
OUT
= 1mA
IN
I
= 3.3V
T
= +85°C
A
R = 3.3kΩ
250
200
150
100
50
C
= 1µF
OUT
V
IN
T
= +25°C
A
200mV/div
V
OUT
20mV/div
T
= -40°C
A
0
0
5
10
LOAD CURRENT (mA)
15
20
100µs/div
0.01
0.1
1
10
100
FREQUENCY (kHz)
LOAD TRANSIENT
TURN-ON/TURN-OFF RESPONSE
C
= 1µF
C
I
= 1µF
OUT
= 1mA - 20mA
OUT
I
= 1mA
OUT
OUT
I
OUT
20mA/div
V
SHDN
2V/div
V
OUT
100mV/div
V
OUT
1V/div
400µs/div
4ms
Detailed Description
Pin Description
The MAX1725/MAX1726 are low-dropout, low-quiescent-
current linear regulators designed primarily for battery-
powered applications (Figure 1). The MAX1725 provides
an adjustable output voltage from 1.5V to 5V using an
external resistor-divider. The MAX1726 supplies preset
output voltages of 1.8V, 2.5V, 3.3V, or 5V. These devices
consist of a +1.245V error amplifier, MOSFET driver,
and P-channel pass transistor (Figure 2).
PIN
NAME
FUNCTION
MAX1725 MAX1726
1
2
1
2
IN
GND
OUT
FB
Supply Voltage Input
Ground
3
3
Voltage Output
4
—
4
Feedback Voltage Input
Ground
—
5
GND
SHDN
5
Active-Low Shutdown Input
4
_______________________________________________________________________________________
12V, Ultra-Low I , Low-Dropout
Q
Linear Regulators
The error amplifier compares 1.245V to the selected
pass to the output. The output voltage is fed back
through either an internal resistor voltage-divider con-
nected to OUT (MAX1726) or an external resistor net-
work connected to FB (MAX1725). Additional features
include an output current limiter, reverse-battery protec-
tion, a thermal sensor, and shutdown logic.
feedback voltage and amplifies the difference. If the
feedback voltage is lower than 1.245V, the pass-tran-
sistor gate is pulled lower, allowing more current to
pass, and thus increasing the output voltage. If the
feedback voltage is higher than 1.245V, the pass-tran-
sistor gate is driven higher, allowing less current to
Internal P-Channel Pass Transistor
The MAX1725/MAX1726 feature a P-channel MOSFET
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 considerably.
PNP-based regulators waste considerable current in
dropout when the pass transistor saturates; they also
use high base-drive currents under large loads. The
MAX1725/MAX1726 do not suffer from these prob-
lems, and consume only 2µA of quiescent current
throughout their load range (see the Typical Operating
Characteristics).
INPUT
OUTPUT
2.5V TO 12V
1.5V TO 5V
IN
OUT
FB
C
C
IN
OUT
1µF
1µF
R1
MAX1725
ON
SHDN
GND
OFF
R2
1.2MΩ
Shutdown
To enter shutdown, drive the SHDN pin below 0.5V.
When the MAX1725/MAX1726 are shut down, the output
Figure 1. Typical Application Circuit
IN
OUT
MAX1725
MAX1726
1.245V
BIAS
CIRCUITRY
THERMAL
SHUTDOWN
(MAX1726 ONLY)
SHDN
FB (MAX1725 ONLY)
GND
Figure 2. Functional Diagram
_______________________________________________________________________________________
5
12V, Ultra-Low I , Low-Dropout
Q
Linear Regulators
pass transistor shuts off, the output falls to ground, and
supply current drops from 2µA to 0.7µA. Connect SHDN
to IN for normal operation. If reverse-battery protection
is needed, drive SHDN through a 100kΩ resistor.
The MAX1725 features an adjustable output voltage
from 1.5V to 5V, using two external resistors connected
as a voltage-divider to FB (Figure 1). The MAX1725 is
optimized for operation with R2 = 1.2MΩ. The output
voltage is set by the following equation:
Thermal-Overload Protection
Thermal-overload protection limits total power dissipa-
tion in the MAX1725/MAX1726. When the junction tem-
R1
R2
V
= V
1 +
OUT
FB
perature exceeds T = +150°C, the thermal sensor
J
signals the shutdown logic, turning off the pass transistor
and allowing the IC to cool. The thermal sensor turns
the pass transistor on again after the IC’s junction tem-
perature cools by 15°C, resulting in a pulsed output
during continuous thermal-overload conditions.
where typically V = 1.245V. To simplify resistor selec-
FB
tion:
V
V
OUT
R1 = R2
−1
Thermal-overload protection is designed to protect the
devices in the event of fault conditions. For continuous
operation, do not exceed the absolute maximum junction
FB
Choose R2 = 1.2MΩ for best accuracy.
temperature rating of T = +150°C.
J
Power-Supply Rejection and Operation
from Sources Other than Batteries
Foldback Current Limiting
The MAX1725/MAX1726 also include a foldback current
limiter. When the output is shorted to ground, the output
PMOS drive is limited so that the output current does
not exceed 40mA (typ). The output can be shorted to
ground indefinitely without damaging the part.
The MAX1725/MAX1726 are designed to deliver low
dropout voltages and low quiescent currents in battery-
powered systems. Power-supply rejection is 60dB at low
frequencies and rolls off above 100Hz. At high frequen-
cies, the output capacitor is the major contributor to the
rejection of power-supply noise (see the Power-Supply
Rejection Ratio vs. Frequency graph in the Typical
Operating Characteristics).
Reverse-Battery Protection
The MAX1725/MAX1726 have a unique protection
scheme that limits the reverse supply current to less
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 (see the
Supply and Load Transient Response graph in the
Typical Operating Characteristics).
than 10µA when V is forced below ground. The cir-
IN
cuitry monitors the polarity of the input, disconnecting
the internal circuitry and parasitic diodes when the battery
is reversed. This feature prevents the device, battery,
and load from overheating and electrical stress. For
reverse-battery protection, drive SHDN through a
100kΩ resistor.
Chip Information
Applications Information
TRANSISTOR COUNT: 112
Capacitor Selection and
Regulator Stability
Pin Configuration
For general purposes, use a 1µF capacitor on the
MAX1725/MAX1726 input and output. Larger input
capacitor values and lower ESR provide better supply-
noise rejection and transient response. A higher-value
input capacitor (10µF) may be necessary if large, fast
transients are anticipated and the device is located sev-
eral inches from the power source. For stable operation
over the full temperature range, use a minimum of 1µF
on the output.
TOP VIEW
IN
GND
OUT
1
2
3
5
SHDN
MAX1725
MAX1726
4
FB (GND)
Output Voltage Selection
For fixed 1.8V, 2.5V, 3.3V, or 5V output voltages, use
the MAX1726.
SOT23-5
( ) ARE FOR MAX1726 ONLY.
6
_______________________________________________________________________________________
12V, Ultra-Low I , Low-Dropout
Q
Linear Regulators
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________7
© 2003 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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