19-1860; Rev 1; 3/01 500mA Low-Dropout Linear Regulator in SOT23 Features ♦ Guaranteed 500mA Output Current ♦ Low 120mV Dropout at 500mA ♦ ±1% Output Voltage Accuracy Preset at 1.5V, 1.8V, 2.0V, 2.5V, 3.3V, 5V Adjustable from 1.25V to 5.0V ♦ Power OK Output ♦ Low 125µA Ground Current ♦ 0.1µA Shutdown Current ♦ Thermal Overload Protection ♦ Output Current Limit ♦ Tiny 800mW 6-Pin SOT23 Package Ordering Information PART* MAX1818EUAT_ _ Applications Notebook Computers Cellular and Cordless Telephones TEMP RANGE PIN-PACKAGE -40°C to +85°C 6 SOT23-6 *Insert the desired two-digit suffix (see Selector Guide) into the blanks to complete the part number. Note: The MAX1818 requires a special solder temperature profile described in the Absolute Maximum Ratings section. Selector Guide Personal Digital Assistants (PDAs) Palmtop Computers PART AND SUFFIX Base Stations SOT23 TOP MARK VOUT USB Hubs MAX1818EUT15 1.5V or Adj AASO Docking Stations MAX1818EUT18 1.8V or Adj AANU MAX1818EUT20 2.0V or Adj AANV MAX1818EUT25 2.5V or Adj AANF MAX1818EUT33 3.3V or Adj AANG MAX1818EUT50 5.0V or Adj AANH Pin Configuration TOP VIEW Typical Operating Circuit VIN = 2.5V TO 5.5V IN NC IN 1 POK 2 MAX1818 6 OUT 5 SET 4 GND VOUT OUT COUT 3.3µF CIN 1µF MAX1818 RPOK 100k ON SHDN 3 SOT23 SHDN POK SET GND OFF TO µC ________________________________________________________________ Maxim Integrated Products 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. 1 MAX1818 General Description The MAX1818 low-dropout linear regulator operates from a +2.5V to +5.5V supply and delivers a guaranteed 500mA load current with low 120mV dropout. The high-accuracy (±1%) output voltage is preset at an internally trimmed voltage (see Selector Guide) or can be adjusted from 1.25V to 5.0V with an external resistive divider. An internal PMOS pass transistor allows the low 125µA supply current to remain independent of load, making this device ideal for portable battery-operated equipment such as personal digital assistants (PDAs), cellular phones, cordless phones, base stations, and notebook computers. Other features include an active-low open-drain reset output that indicates when the output is out of regulation, a 0.1µA shutdown, short-circuit protection, and thermal shutdown protection. The device is available in a miniature 800mW 6-pin SOT23 package. MAX1818 500mA Low-Dropout Linear Regulator in SOT23 ABSOLUTE MAXIMUM RATINGS IN, SHDN, POK, SET to GND ...................................-0.3V to +6V OUT to GND ................................................-0.3V to (VIN + 0.3V) Output Short-Circuit Duration ...............................................1min Continuous Power Dissipation (TA = +70°C) (Note 1) 6-Pin SOT23 (derate 10mW/°C above +70°C)..............800mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) (Note 2) ...................+300°C Note 1: Thermal properties are specified with product mounted on PC board with one square-inch of copper area and still air. With minimal copper, the SOT23 package dissipates 712mW at +70°C. With a quarter square inch of copper, it will dissipate 790mW at +70°C. Copper should be equally shared between the IN, OUT, and GND pins. Note 2: This device is constructed using a unique set of packaging techniques that imposes a limit on the thermal profile to which the device can be exposed during board-level solder attach and rework. The limit permits only the use of the solder profiles recommended in the industry standard specification, IPC JEDEC-J-STD-020A, paragraph 7.6, Table 3 for the IR/VPR and convection reflow. Preheating is required. Hand or wave soldering is not allowed. 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 (VIN = VOUT + 500mV or VIN = +2.5V, whichever is greater; SHDN = IN, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3) PARAMETER Input Voltage Input Undervoltage Lock-Out Output Voltage Accuracy (Preset Mode) SYMBOL CONDITIONS VIN VUVLO VOUT Guaranteed Output Current (RMS) IOUT Short-Circuit Current Limit ILIM Ground-Pin Current Dropout Voltage (Note 4) Line Regulation IQ VIN - VOUT ∆VLNR IOUT = 100mA, VOUT < 2.0V -1.5 +1.5 IOUT = 100mA, TA = -40°C to +85°C -2.5 +2.5 -3 +3 1.25 5 TA = 0°C to +85°C 1.225 TA = -40°C to +85°C 1.213 1.250 V 1.275 V VIN ≥ 2.7V 500 VOUT = 0, VIN ≥ 2.7V 0.55 VSET = 1.25V mA 0.8 1.8 A 150 mV +100 nA 1.6 100 -100 IOUT = 100µA 125 IOUT = 500mA 140 IOUT = 500mA % 1.288 A 250 VOUT = 5V 100 220 VOUT = 3.3V 120 215 VOUT = 2.5V 210 360 0 +0.15 VIN from (VOUT + 100mV) to 5.5V, ILOAD = 5mA -0.15 Dual Mode is a trademark of Maxim Integrated Products 2 V +1 50 ISET 2.3 -1 SET Dual Mode™ Threshold SET Input Bias Current V 2.0 VOUT > 96% of nominal value, VIN ≥ 2.7V In-Regulation Current Limit UNITS 5.5 IOUT = 100mA, TA = +25°C, VOUT ≥ 2.0V VIN = 2.7V, IOUT = 100mA, VOUT set to 2.0V 2.15 MAX Rising, 75mV hysteresis Adjustable Output Voltage Range VSET TYP 2.5 IOUT = 1mA to 500mA, VIN > VOUT + 0.5V, TA = -40°C to +85°C SET Voltage Threshold (Adjustable Mode) MIN _______________________________________________________________________________________ µA mV %/V 500mA Low-Dropout Linear Regulator in SOT23 (VIN = VOUT + 500mV or VIN = +2.5V, whichever is greater; SHDN = IN, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3) PARAMETER SYMBOL ∆VLDR Load Regulation Output Voltage Noise CONDITIONS MIN TYP MAX IOUT = 1mA to 500mA 0.4 1.0 10Hz to 1MHz, COUT = 3.3µF (ESR < 0.1Ω) 115 UNITS % µVRMS SHUTDOWN Shutdown Supply Current SHDN Input Threshold SHDN Input Bias Current IOFF SHDN = GND, VIN = 5.5V VIH 2.5V < VIN < 5.5V VIL 2.5V < VIN < 5.5V I SHDN 0.1 15 µA 1.6 V 0.6 SHDN = IN or GND, TA = +25°C 1 TA = +85°C 5 25 nA POK OUTPUT POK Output Low Voltage VOL POK sinking 1mA Operating Voltage Range for Valid POK 0.01 POK sinking 100µA 1.0 POK Output High Leakage Current POK = 5.5V, TA = +25°C 1 TA = +85°C 5 POK Threshold Rising edge, referred to VOUT(NOMINAL) 90 0.1 V 5.5 V 25 93 nA 96 % THERMAL PROTECTION TSHDN 170 °C ∆TSHDN 20 °C Thermal Shutdown Temperature Thermal Shutdown Hysteresis Note 3: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design. Note 4: The Dropout Voltage is defined as VIN - VOUT, when VOUT is 100mV below the value of VOUT measured for VIN = VOUT(NOM) + 500mV. Since the minimum input voltage is 2.5V, this specification is only meaningful when VOUT(NOM) > 2.5V. For VOUT(NOM) between 2.5V and 3.5V, use the following equations: Typical Dropout = -93mV/V ✕ VOUT(NOM) + 445mV; Guaranteed Maximum Dropout = -137mV/V ✕ VOUT(NOM) +7004mV. For VOUT(NOM) > 3.5V, Typical Dropout = 120mV; Maximum Dropout = 220mV. Typical Operating Characteristics (VIN = (VOUT + 500mV) or +2.5V, whichever is greater; SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA = +25°C, unless otherwise noted.) 175 150 125 100 3.3V OUTPUT 1.8V OUTPUT 2.5V OUTPUT 75 50 145 130 2.5V OUTPUT 115 1.8V OUTPUT 3.3V OUTPUT 100 85 70 0 INPUT VOLTAGE (V) 5.0V OUTPUT 150 140 1.5V OUTPUT 130 110 40 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 ILOAD = 150mA 160 120 55 25 170 GROUND PIN CURRENT (µA) 200 160 MAX1818 toc02 ILOAD = 150mA GROUND PIN CURRENT (µA) GROUND PIN CURRENT (µA) 225 MAX1818 toc01 250 GROUND PIN CURRENT vs. TEMPERATURE GROUND PIN CURRENT vs. LOAD CURRENT MAX1818 toc03 GROUND PIN CURRENT vs. INPUT VOLTAGE 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 LOAD CURRENT (A) -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX1818 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VIN = (VOUT + 500mV) or +2.5V, whichever is greater; SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA = +25°C, unless otherwise noted.) OUTPUT VOLTAGE ACCURACY vs. LOAD CURRENT 90 TA = +25°C 60 TA = -40°C 30 0 0.1 0.2 0.3 0.4 2.5V OUTPUT 1.8V OUTPUT 0 0.5 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 LOAD CURRENT (A) LOAD CURRENT (A) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY LINE TRANSIENT 80 70 COUT = 3.3µF 60 VOUT = 1.5V TO 5.0V -40 -15 10 ILOAD = 150mA 35 60 85 TEMPERATURE (°C) VOUT VOUT = 3.3V LOAD-TRANSIENT RESPONSE MAX1818 toc09 VIN = 3.3V VOUT = 2.5V IOUT 500mA 100mA RLOAD = 100Ω 50 MAX1818 toc06 3.0 2.5 2.0 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 MAX1818 toc08 MAX1818 toc07 0 3.3V OUTPUT 2.5V 10mV/div DROPOUT VOLTAGE (mV) 120 OUTPUT VOLTAGE ACCURACY (%) TA = +85°C 150 3.0 2.5 2.0 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 OUTPUT VOLTAGE ACCURACY vs. TEMPERATURE MAX1818 toc05 VOUT = 3.3V OUTPUT VOLTAGE ACCURACY (%) 180 MAX1818 toc04 DROPOUT VOLTAGE vs. LOAD CURRENT PSRR (dB) 3.5V 500mV/div 30 VIN 20 20mV/div 40 VOUT 10 0 0.01 0.1 1 10 100 100µs/div 1000 40µs/div FREQUENCY (kHz) LOAD-TRANSIENT RESPONSE NEAR DROPOUT POWER-ON RESET MAX1818 toc11 MAX1818 toc10 VOUT 100mV/div VIN = VOUT + 100mV VOUT = 3.3V VPOK 0 VOUT 200mA IOUT MAX1818 500mA Low-Dropout Linear Regulator in SOT23 2V/div 0 VIN 0 0 10µs/div 4 10ms/div _______________________________________________________________________________________ 500mA Low-Dropout Linear Regulator in SOT23 SHORT-CIRCUIT CURRENT LIMIT vs. SUPPLY VOLTAGE SHUTDOWN WAVEFORM MAX1818 toc12 0 VOUT 0 2V/div 0 POK MAX1818 toc13 SHORT-CIRCUIT CURRENT LIMIT (A) SHUTDOWN VOLTAGE 1.11 VOUT(NOM) = +2V 1.10 1.09 1.08 1.07 1.06 1.05 1.04 1.03 1.02 1.01 1.00 2.5 200µs/div 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) Pin Description PIN NAME FUNCTION 1 IN Regulator Input. Supply voltage can range from 2.5V to 5.5V. Bypass with a 1µF capacitor to GND (see Capacitor Selection and Regulator Stability). 2 POK Open-Drain POK Output. POK remains low while the output voltage (VOUT) is below the POK threshold. Connect a 100kΩ pull-up resistor from POK to OUT to obtain an output voltage. 3 SHDN Active-Low Shutdown Input. A logic low reduces supply current below 15µA. In shutdown, the POK output is low, and OUT is high impedance. Connect to IN for normal operation. 4 GND Ground 5 SET Voltage-Setting Input. Connect to GND for preset output. Connect to a resistive voltage-divider between OUT and GND to set the output voltage between 1.25V and 5.0V. 6 OUT Regulator Output. Sources up to 500mA. Bypass with a 3.3µF low-ESR capacitor to GND. Use a 4.7µF capacitor for output voltages below 2V. Detailed Description The MAX1818 is a low-dropout, low-quiescent-current linear regulator designed primarily for battery-powered applications. The device supplies loads up to 500mA and is available with preset output voltages. As illustrated in Figure 1, the MAX1818 consists of a 1.25V reference, error amplifier, P-channel pass transistor, and internal feedback voltage-divider. The 1.25V reference is connected to the which compares this reference with the age and amplifies the difference. If the age is lower than the reference error amplifier, feedback voltfeedback voltvoltage, the pass-transistor gate is pulled lower, which allows more current to pass to the output and increases the output voltage. If the feedback voltage is too high, the passtransistor gate is pulled up, allowing less current to pass to the output. The output voltage is fed back through either an internal resistive divider connected to OUT or an external resistor network connected to SET. The Dual Mode comparator examines VSET and selects the feedback path. If VSET is below 50mV, the internal feedback path is used and the output is regulated to the factory-preset voltage. _______________________________________________________________________________________ 5 MAX1818 Typical Operating Characteristics (continued) (VIN = (VOUT + 500mV) or +2.5V, whichever is greater; SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA = +25°C, unless otherwise noted.) MAX1818 500mA Low-Dropout Linear Regulator in SOT23 VIN = 2.5V TO 5.5V IN CIN 1µF THERMAL SENSOR MOSFET DRIVER WITH I LIM OUT ON VOUT = 1.25V TO 5.0V SHDN OFF COUT 3.3µF SHUTDOWN LOGIC 5k VREF 1.25V ERROR AMPLIFIER LOGIC SUPPLY VOLTAGE (VOUT) RPOK 100k R1 MAX1818 POK TO µC SET R2 93% VREF 100mV GND Figure 1. Functional Diagram Additional blocks include an output current limiter, thermal sensor, and shutdown logic. Internal P-Channel Pass Transistor The MAX1818 features a 0.25Ω P-channel MOSFET pass transistor. Unlike similar designs using PNP pass transistors, P-channel MOSFETs require no base drive, which reduces quiescent current. PNP-based regulators also waste considerable current in dropout when the pass transistor saturates, and use high base-drive currents under large loads. The MAX1818 does not suffer from these problems and consumes only 125µA of quiescent current under heavy loads as well as in dropout. Output Voltage Selection The MAX1818’s Dual Mode operation allows operation in either a preset voltage mode or an adjustable mode. Connect SET to GND to select the preset output voltage. The two-digit part number suffix identifies the out- 6 put voltage (see Selector Guide). For example, the MAX1818EUT33 has a preset 3.3V output voltage. The output voltage may also be adjusted by connecting a voltage-divider from OUT to SET to GND (Figure 2). Select R2 in the 25kΩ to 100kΩ range. Calculate R1 with the following equation: R1 = R2 [(VOUT / VSET) – 1] where VSET = 1.25V, and VOUT may range from 1.25V to 5.0V. Shutdown Pull SHDN low to enter shutdown. During shutdown, the output is disconnected from the input and supply current drops to 0.1µA. When in shutdown, POK pulls low and OUT is high impedance. The capacitance and load at OUT determine the rate at which V OUT decays. SHDN can be pulled as high as 6V, regardless of the input and output voltage. _______________________________________________________________________________________ 500mA Low-Dropout Linear Regulator in SOT23 CIN 1µF COUT 3.3µF MAX1818 R1 ON SHDN SET OFF TA = +85°C TA = +70°C MAXIMUM RECOMMENDED OUTPUT CURRENT 400 VOUT = 1.8V 200 VOUT = 2.5V VOUT = 3.3V R2 POK MAX1818 fig03 600 OUT MAXIMUM OUTPUT CURRENT (mA) IN -1 1.25V VOUT MAXIMUM INPUT VOLTAGE V IN = 2.5V TO 5.5V MAX1818 R1 = R2 MAXIMUM OUTPUT CURRENT vs. INPUT VOLTAGE (POWER DISSIPATION LIMIT) VOUT 0 GND 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 INPUT VOLTAGE (V) Figure 2. Adjustable Output Using External Feedback Resistors POK Output The power OK (POK) output pulls low when OUT is less than 93% of the nominal regulation voltage. Once OUT exceeds 93% of the nominal voltage, POK goes high impedance. POK is an open-drain N-channel output. To obtain a voltage output, connect a pullup resistor from POK to OUT. A 100kΩ resistor works well for most applications. POK can be used as a power-okay (POK) signal to a microcontroller (µC), or drive an external LED to indicate power failure. When the MAX1818 is shut down, POK is held low independent of the output voltage. If unused, leave POK grounded or unconnected. Current Limit The MAX1818 monitors and controls the pass transistor’s gate voltage, limiting the output current to 0.8A (typ). This current limit doubles when the output voltage is within 4% of the nominal value to improve performance with large load transients. Thermal Overload Protection Thermal overload protection limits total power dissipation in the MAX1818. When the junction temperature exceeds TJ = +170°C, a thermal sensor turns off the pass transistor, allowing the IC to cool. The thermal sensor turns the pass transistor on again after the junction temperature cools by 20°C, resulting in a pulsed output during continuous thermal overload conditions. Thermal overload protection protects the MAX1818 in Figure 3. Power Operating Regions: Maximum Output vs. Supply Voltage the event of fault conditions. For continuous operation, do not exceed the absolute maximum junction-temperature rating of TJ = +150°C. Operating Region and Power Dissipation The MAX1818’s maximum power dissipation depends on the thermal resistance of the IC package and circuit board, the temperature difference between the die junction and ambient air, and the rate of air flow. The power dissipated in the device is P = IOUT × (VIN V OUT ). The maximum allowed power dissipation is 800mW at TA = +70°C or: PMAX = (TJ(MAX) - TA) / ( θJC + θCA) where TJ - TA is the temperature difference between the MAX1818 die junction and the surrounding air, θJC is the thermal resistance of the junction to the case, and θ CA is the thermal resistance from the case through the PC board, copper traces, and other materials to the surrounding air. For best heatsinking, the copper area should be equally shared between the IN, OUT, and GND pins. The MAX1818 delivers up to 0.5A RMS and operates with input voltages up to +5.5V, but not simultaneously. High output currents can only be sustained when inputoutput differential voltages are low, as shown in Figure 3. _______________________________________________________________________________________ 7 MAX1818 500mA Low-Dropout Linear Regulator in SOT23 Applications Information Capacitor Selection and Regulator Stability Capacitors are required at the MAX1818’s input and output for stable operation over the full temperature range and with load currents up to 500mA. Connect a 1µF capacitor between IN and ground and a 3.3µF lowESR capacitor between OUT and ground. For output voltages less than 2V, use a 4.7µF low-ESR output capacitor. The input capacitor (CIN) lowers the source impedance of the input supply. Reduce noise and improve load-transient response, stability, and powersupply rejection by using larger output capacitors, such as 10µF. The output capacitor’s (COUT) equivalent series resistance (ESR) affects stability and output noise. Use output capacitors with an ESR of 0.1Ω or less to ensure stability and optimum transient response. Surfacemount ceramic capacitors have very low ESR and are commonly available in values up to 10µF. Connect CIN and COUT as close to the MAX1818 as possible to minimize the impact of PC board trace inductance. Noise, PSRR, and Transient Response The MAX1818 is designed to operate with low dropout voltages and low quiescent currents in battery-powered systems while still maintaining good noise, transient response, and AC rejection. See the Typical Operating Characteristics for a plot of power-supply rejection ratio (PSRR) versus frequency. When operating from noisy sources, improved supply-noise rejection and transient response can be achieved by increasing the values of 8 the input and output bypass capacitors and through passive filtering techniques. The MAX1818 load-transient response (see Typical Operating Characteristics) shows two components of the output response: a DC shift from the output impedance due to the load current change, and the transient response. A typical transient response for a step change in the load current from 100mA to 500mA is 8mV. Increasing the output capacitor’s value and decreasing the ESR attenuates the overshoot. Input-Output (Dropout) Voltage A regulator’s minimum input-to-output voltage differential (dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the MAX1818 uses a P-channel MOSFET pass transistor, its dropout voltage is a function of drain-tosource on-resistance (RDS(ON)) multiplied by the load current (see Typical Operating Characteristics). VDROPOUT = VIN - VOUT = RDS(ON) × IOUT The MAX1818 ground current remains below 150µA in dropout. Chip Information TRANSISTOR COUNT: 845 _______________________________________________________________________________________ 500mA Low-Dropout Linear Regulator in SOT23 6LSOT.EPS 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 ______________________9 © 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX1818 Package Information