MAX1725/MAX1726 12V, Ultra-Low IQ, Low-Dropout 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. 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 protection, short-circuit protection, and thermal protection. o 2µA Supply Current The MAX1725 provides an adjustable 1.5V to 5V output using an external resistor-divider. The MAX1726 provides factory preset 1.8V, 2.5V, 3.3V, or 5V output voltages (see the Ordering Information). Both devices are available in a tiny 5-pin SOT23 package. o Tiny 5-Pin SOT23 Package o Reverse-Battery Protection o +2.5V to +12V Input Voltage Range o Fixed 1.8V, 2.5V, 3.3V, and 5V Output Voltages (MAX1726) o Adjustable 1.5V to 5V Output Voltages (MAX1725) o 20mA Guaranteed Output Current o 1.5% Output Voltage Accuracy o Small 1µF Output Capacitor o Short-Circuit Protection o Thermal Protection Ordering Information PART ________________________Applications TEMP RANGE PIN- TOP PACKAGE MARK MAX1725EUK+T -40°C to +85°C 5 SOT23 Smoke Detectors MAX1726EUK18+T -40°C to +85°C 5 SOT23 ADNL Remote Transmitters MAX1726EUK25+T -40°C to +85°C 5 SOT23 ADNM Smart Battery Packs MAX1726EUK25/V+T -40°C to +85°C 5 SOT23 AFMN MAX1726EUK33+T -40°C to +85°C 5 SOT23 ADNN MAX1726EUK50+T -40°C to +85°C 5 SOT23 ADNO Industrial Control Systems Microcontroller Power ADNK +Denotes a lead(Pb)-free/RoHS-compliant package. /V denotes an automotive-qualified part. Note: See the Selector Guide for the output options as they relate to the part number suffix. Real-Time Clock Backup Power PDAs and Handy-Terminals Battery-Powered Alarms Typical Operating Circuit Selector Guide PART VIN 2.5V TO 12V IN OUT MAX1726 ON OFF SHDN GND OUTPUT 1.5V TO 5V OUTPUT VOLTAGE (V) MAX1725EUK+T Adj 1.5 to 5.0 MAX1726EUK18+T Fixed 1.8 MAX1726EUK25+T Fixed 2.5 MAX1726EUK25/V+T Fixed 2.5 MAX1726EUK33+T Fixed 3.3 MAX1726EUK50+T Fixed 5.0 Pin Configuration appears at end of data sheet. For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com. 19-1680; Rev 2; 11/12 MAX1725/MAX1726 12V, Ultra-Low IQ, Low-Dropout Linear Regulators ABSOLUTE MAXIMUM RATINGS IN to GND ................................................................-14V to +14V SHDN to GND ..............................................-0.3V to (VIN + 0.3V) (-0.3V to + 0.3V when VIN < 0V) OUT, FB (MAX1725 only) to GND...................-0.3V to +6V when VIN >5.7V; -0.3V to (VIN + 0.3V) when 0V < VIN < 5.7V; -0.3V to +0.3V when VIN < 0V OUT Continuous Current...................................................200mA OUT Short Circuit...........................................................Indefinite Continuous Power Dissipation (TA = +70°C) 5-Pin SOT23 (derate 7.1mW/°C above +70°C)............571mW 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 Soldering Temperature (reflow) .......................................+260°C 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. PACKAGE THERMAL CHARACTERISTICS (Note 1) Junction-to-Ambient Thermal Resistance (θJA)...............140°C/W Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial. ELECTRICAL CHARACTERISTICS (Circuit of Figure 1, VIN = VOUT + 1V, SHDN = IN, IOUT = 1mA, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS Input Voltage Range VIN (Note 3) Supply Current IIN VIN = 12V Shutdown Supply Current OUT Voltage Range FB Voltage IIN(SHDN) VOUT VFB 2 V SHDN = 0V, VIN = 12V, VOUT = 0V MAX1725 only 0.7 1.5 MAX1725 only (Note 4) MAX UNITS 12 V 4.5 µA 2 µA 5 V 1.245 V -1.5 1.5 TA = 0°C to +85°C -2 +2 TA = -40°C to +85°C -3 +3 % Line Regulation ∆VLNR VIN = 2.5V or (VOUT + 0.5V) to 12V 0.01 0.3 %/V Load Regulation ∆VLDR IOUT = 1mA to 20mA, VIN = (VOUT + 1V) or 3V (min) 0.015 0.15 %/mA Maximum OUT Current IOUT VIN = (VOUT + 1V) or 3V (Note 5) Dropout Voltage (Note 5) ∆VDO IOUT = 20mA for VOUT ≥ 2.5V, IOUT = 10mA for VOUT < 2.5V, not applicable for VOUT < 1.9V Foldback Current Limit SHDN Input Threshold SHDN Input Bias Current FB Input Bias Current (MAX1725 only) ISC VIH VIL I SHDN IFB 20 300 VIN = 12V, VOUT = 0V VFB = 1.25V mA 600 40 0.5 TA = +25°C -50 TA = +85°C TA = +25°C TA = +85°C +50 0.1 -20 2 mV mA 2 VIN = 2.5V to 12V V SHDN = 0V to 12V 80 +20 1.5 10 V nA nA IN Reverse Leakage Current VIN = -12V, V SHDN = 0V 0.01 Thermal-Shutdown Threshold Temperature rising 150 °C 15 °C Thermal-Shutdown Hysteresis 2 TYP 2.5 TA = +25°C OUT Voltage Accuracy (Note 4) MIN µA Maxim Integrated MAX1725/MAX1726 12V, Ultra-Low IQ, Low-Dropout Linear Regulators ELECTRICAL CHARACTERISTICS (continued) (Circuit of Figure 1, VIN = VOUT + 1V, SHDN = IN, IOUT = 1mA, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS OUT Line-Transient Overshoot/Undershoot ∆VIN = ±0.25V, tR = tF = 5µs 15 mV OUT Load-Transient Overshoot/Undershoot IOUT from 1mA to 10mA, tR = tF = 1µs 200 mV f = 10Hz to 100kHz 350 µVRMS OUT Noise Note 2: Note 3: Note 4: Note 5: en Limits are 100% production tested at +25°C. All temperature limits are guaranteed by design. Guaranteed by OUT line-regulation testing. OUT accuracy from nominal voltage. The MAX1725 is tested at VOUT = 1.5V, 2.5V, and 5V. When VOUT falls to 4% below its value at VIN = VOUT + 1V. Typical Operating Characteristics (VOUT = +3.3V, IOUT = 1mA, TA = +25°C, unless otherwise noted.) 2 3 2 5 6 7 8 9 10 11 2 0 0 12 3 1 0 4 VIN = 5V 4 1 0 MAX1725/26 toc03 MAX1725/26 toc02 VIN = 5V 4 1 5 10 15 20 -40 -20 0 20 40 60 TEMPERATURE (°C) OUTPUT VOLTAGE vs. INPUT VOLTAGE OUTPUT VOLTAGE vs. LOAD CURRENT NORMALIZED OUTPUT VOLTAGE vs. TEMPERATURE -0.4 ILOAD = 1mA -0.6 -0.8 -1.0 ILOAD = 20mA -1.2 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.4 4 5 6 7 8 9 INPUT VOLTAGE (V) Maxim Integrated 10 11 12 0.30 80 MAX1725/26 toc06 NOMINAL OUTPUT = 3.3V VIN = 4.5V 0.6 NORMALIZED OUTPUT VOLTAGE (%) -0.2 0.8 OUTPUT VOLTAGE (% DEVIATION) NOMINAL OUTPUT = 3.3V MAX1725/26 toc05 LOAD CURRENT (mA) MAX1725/26 toc04 INPUT VOLTAGE (V) 0 OUTPUT VOLTAGE (%DEVIATION) 5 SUPPLY CURRENT (µA) 3 5 SUPPLY CURRENT (µA) MAX1725/26 toc01 SUPPLY CURRENT (µA) 4 SUPPLY CURRENT vs. TEMPERATURE SUPPLY CURRENT vs. LOAD CURRENT SUPPLY CURRENT vs. INPUT VOLTAGE 5 0.20 0.10 IOUT = 1mA 0 -0.10 -0.20 -0.30 0 2 4 6 8 10 12 14 16 18 20 LOAD CURRENT (mA) -40 -20 0 20 40 60 80 TEMPERATURE (°C) 3 MAX1725/MAX1726 12V, Ultra-Low IQ, Low-Dropout Linear Regulators Typical Operating Characteristics (continued) (VOUT = +3.3V, IOUT = 1mA, TA = +25°C, unless otherwise noted.) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY TA = +25°C 150 VIN = 5V VOUT = 3.3V RL = 3.3kΩ COUT = 1µF 70 60 PSRR (dB) VIN 200mV/div 50 40 30 100 VOUT 20mV/div 20 TA = -40°C 50 10 0 0 0 5 10 15 0.01 20 0.1 1 10 100µs/div 100 FREQUENCY (kHz) LOAD CURRENT (mA) TURN-ON/TURN-OFF RESPONSE COUT = 1µF IOUT = 1mA - 20mA IOUT 20mA/div MAX1725/26 toc10 LOAD TRANSIENT COUT = 1µF IOUT = 1mA VSHDN 2V/div VOUT 100mV/div VOUT 1V/div 400µs/div Pin Description PIN NAME FUNCTION MAX1725 MAX1726 4 COUT = 1µF IOUT = 1mA MAX1725/26 toc11 DROPOUT VOLTAGE (mV) 200 LINE-TRANSIENT RESPONSE 1 1 IN Supply Voltage Input 2 2 GND Ground 3 3 OUT Voltage Output 4 — FB — 4 GND Ground 5 5 SHDN Active-Low Shutdown Input 4ms Detailed Description The MAX1725/MAX1726 are low-dropout, low-quiescentcurrent linear regulators designed primarily for batterypowered 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). Feedback Voltage Input Maxim Integrated MAX1725/26 toc09 TA = +85°C 250 80 MAX1725/26 toc07 300 MAX1725/26 toc08 DROPOUT VOLTAGE vs. LOAD CURRENT MAX1725/MAX1726 12V, Ultra-Low IQ, Low-Dropout Linear Regulators The error amplifier compares 1.245V to the selected feedback voltage and amplifies the difference. If the feedback voltage is lower than 1.245V, the pass-transistor 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- INPUT 2.5V TO 12V CIN 1µF OUTPUT 1.5V TO 5V IN OUT R1 MAX1725 ON OFF SHDN COUT 1µF FB GND R2 1.2MΩ Figure 1. Typical Application Circuit sistor 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 (MAX1726) or an external resistor network connected to FB (MAX1725). Additional features include an output current limiter, reverse-battery protection, a thermal sensor, and shutdown logic. 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 problems, and consume only 2µA of quiescent current throughout their load range (see the Typical Operating Characteristics). IN OUT MAX1725 MAX1726 BIAS CIRCUITRY THERMAL SHUTDOWN 1.245V (MAX1726 ONLY) SHDN FB (MAX1725 ONLY) GND Figure 2. Functional Diagram Maxim Integrated 5 MAX1725/MAX1726 12V, Ultra-Low IQ, Low-Dropout Linear Regulators Shutdown To enter shutdown, drive the SHDN pin below 0.5V. When the MAX1725/MAX1726 are shut down, the output 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. Thermal-Overload Protection Thermal-overload protection limits total power dissipation in the MAX1725/MAX1726. When the junction temperature exceeds T J = +150°C, the thermal sensor 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 temperature cools by 15°C, resulting in a pulsed output during continuous thermal-overload conditions. 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 temperature rating of TJ = +150°C. 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. Reverse-Battery Protection The MAX1725/MAX1726 have a unique protection scheme that limits the reverse supply current to less than 10µA when VIN is forced below ground. The circuitry 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. Applications Information Capacitor Selection and Regulator Stability For general purposes, use a 1µF capacitor on the MAX1725/MAX1726 input and output. Larger input capacitor values and lower ESR provide better supply- 6 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 several inches from the power source. For stable operation R1 ⎞ ⎛ VOUT = VFB ⎜1 + ⎟ ⎝ R2 ⎠ over the full temperature range, use a minimum of 1µF on the output. ⎛V ⎞ R1 = R2 ⎜ OUT − 1⎟ V ⎝ FB ⎠ Output-Voltage Selection For fixed 1.8V, 2.5V, 3.3V, or 5V output voltages, use the MAX1726. 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: where typically VFB = 1.245V. To simplify resistor selection: Choose R2 = 1.2MΩ for best accuracy. Power-Supply Rejection and Operation from Sources Other than Batteries The MAX1725/MAX1726 are designed to deliver low dropout voltages and low quiescent currents in batterypowered systems. Power-supply rejection is 60dB at low frequencies and rolls off above 100Hz. At high frequencies, 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). When operating from sources other than batteries, improve supply-noise rejection and transient response by increasing the value of the input and output capacitors, and by using passive filtering techniques (see the Supply and Load Transient Response graph in the Typical Operating Characteristics). Maxim Integrated MAX1725/MAX1726 12V, Ultra-Low IQ, Low-Dropout Linear Regulators Chip Information Package Information Pin Configuration For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. TRANSISTOR COUNT: 112 TOP VIEW + IN 1 GND 2 Maxim Integrated SHDN 4 FB (GND) PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 5 SOT23 U5+1 21-0057 90-0174 MAX1725 MAX1726 OUT 3 ( ) ARE FOR MAX1726 ONLY. 5 PACKAGE TYPE SOT23 7 MAX1725/MAX1726 12V, Ultra-Low IQ, Low-Dropout Linear Regulators Revision History REVISION NUMBER REVISION DATE 2 11/12 DESCRIPTION Added MAX1726EUK26/V+ and “+” lead(Pb)-free designations to Ordering Information PAGES CHANGED 1 Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. 8 ________________________________Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 © 2012 Maxim Integrated Products, Inc. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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