19-218; Rev ; 4/1 5mA, Low-Voltage Linear Regulator in µmax General Description The low-dropout linear regulator operates from a +2.25V to +5.5V supply and delivers a guaranteed 5mA load current with low 175mV dropout. The high-accuracy (±1%) output voltage is preset at an internally trimmed voltage (see Selector Guide) or can be adjusted from +.8V to +4.5V with an external resistive-divider. An internal PMOS pass transistor allows low 21µA supply current, making this device ideal for portable equipment such as personal digital assistants (PDAs), cellular phones, cordless phones, and other equipment, including base stations and docking stations. Other features include an active-low, power-ok output that indicates when the output is out of regulation, a.2µa shutdown mode, short-circuit protection, and thermal shutdown protection. The comes in a miniature 1.3W, 8-pin power-µmax package with a metal pad on the underside of the package. Notebook Computers Cellular and Cordless Telephones PDAs Palmtop Computers Base Stations USB Hubs Docking Stations Applications Typical Operating Circuit Guaranteed 5mA Output Current Output Down to.8v Low 175mV Dropout at 5mA ±1% Output Voltage Accuracy Preset at.8v, 1.5V, 1.8V, 2.5V, or 3.3V Adjustable from.8v to 4.5V Power-OK Output Low 21µA Ground Current.2µA Shutdown Current Thermal Overload Protection Output Current Limit Tiny 1.3W, 8-Pin Power-µMAX Package Features Ordering Information PART T EM P. R A N G E P-PACKAGE EUA -4 C to +85 C 8 Power-µMAX Selector Guide PART AND SUFFIX (V) TOP MARK EUA33 3.3 AAAG EUA25 2.5 AAAH EUA18 1.8 AAAI EUA15 1.5 AAAJ EUA8.8 AAAK Pin Configuration V +2.25V TO +5.5V NC.8V TO 4.5V TOP VIEW C 1µF C 1µF 1 8 ON OFF SHDN POK R POK 1kΩ TO µc POK SHDN 2 3 4 7 6 5 SET GND SET GND µmax 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.
5mA, Low-Voltage Linear Regulator in µmax ABSOLUTE MAXIMUM RATGS, SHDN, POK, SET to GND...-.3V to +6V to GND...-.3V to (V +.3V) Output Short-Circuit Duration...Continuous Continuous Power Dissipation (T A = +7 C) 8-Pin Power-µMAX (derate 17mW/ C above +7 C)...1.3W Operating Temperature...-4 C to +85 C Junction Temperature...+15 C Storage Temperature Range...-65 C to +15 C Lead Temperature (soldering, 1s)...+3 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. ELECTRICAL CHARACTERISTICS (V = (SETPOT) + 5mV or V = +2.25V whichever is greater, SET = GND, SHDN =, T A = C to +85 C, unless otherwise noted. Typical values are at T A = +25 C.) PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS Input Voltage V 2.25 5.5 V Input Undervoltage Lockout V UVLO Rising, 4mV hysteresis 1.85 2. 2.15 V Output Voltage Accuracy (Preset Mode) T A = +85 C, I = 1mA -1 +1 T A = +85 C, I = 1mA to 5mA -1.5 +1.5 T A = C to +85 C, I = 1mA to 5mA, V > +.5V -3 +3 Adjustable Output Voltage.8 4.5 V T A = +85 C, I = 1mA 79 81 % SET Voltage Threshold (Adjustable Mode) V SET T A = +85 C, I = 1mA to 5mA 786 814 T A = C to +85 C, I = 1mA to 5mA, V > +.5V 774 8 826 mv Maximum Output Current I 5 m A RM S Short-Circuit Current Limit I LIM = V 7 14 23 ma SET Dual Mode Threshold 35 8 125 mv SET Input Bias Current I SET V SET = +.8V -1 +1 na I = 1mA 21 4 Ground-Pin Current I Q I = 5mA 575 Dropout Voltage (Note 1) I = 5mA = +2.25V 259 384 = +2.8V 21 315 = +4.V 147 255 Line Regulation V LNR V I N fr om ( V OU T + 1m V ) to 5.5V, I L OA D = 5m A.125 %/V Load Regulation V LDR I = 1mA to 5mA 15.5 35 p p m /m A Output Voltage Noise 1Hz to 1MHz, C = 1µF (ESR <.1Ω) 3 µv RMS SHUTDOWN Shutdown Supply Current I OFF SHDN = GND, V = 5.5V.2 5 µa SHDN Input Threshold V IH 1.6 V IL.6 SHDN Input Bias Current I SHDN SHDN = GND or 1 1 na Startup Time T START C = 1µF, ti m e fr om SHDN hig h to P OK hig h 4 µs Dual Mode is a trademark of Maxim Integrated Products, Inc. µa mv V 2
5mA, Low-Voltage Linear Regulator in µmax ELECTRICAL CHARACTERISTICS (continued) (V = (SETPOT) + 5mV or V = +2.25V whichever is greater, SET = GND, SHDN =, T A = C to +85 C, unless otherwise noted. Typical values are at T A = +25 C.) POWER-OK PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS POK Output Low Voltage V OL Sinking 2mA 5 5 mv Operating Voltage Range for Valid POK Output Sinking 1µA 1. 5.5 V Output High-Leakage Current V POK = +5.5V 1 na Threshold Rising edge, referred to (NOMAL) 9 93 96 % THERMAL PROTECTION Ther m al S hutd own Tem p erature T SHDN 17 C Thermal Shutdown Hysteresis T SHDN 2 C ELECTRICAL CHARACTERISTICS (V = (SETPOT) + 5mV or V = +2.25V whichever is greater, SET = GND, SHDN =, T A = -4 C to +85 C, unless otherwise noted. Typical values are at T A = +25 C.) (Note 2) PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS Input Voltage V 2.25 5.5 V Input Undervoltage Lockout V UVLO Rising, 4mV hysteresis 1.85 2.15 V Output Voltage Accuracy (Preset Mode) I = 1mA to 5mA -4 +4 % Adjustable Output Voltage.8 4.5 V SET Voltage Threshold (Adjustable Mode) V SET I = 1mA to 5mA 766 834 mv Maximum Output Current I 5 m A RM S Short-Circuit Current Limit I LIM = V 7 25 ma SET Dual Mode Threshold 35 125 mv SET Input Bias Current I SET V SET = +.8V -1 +1 na Ground-Pin Current I Q I = 1mA 4 µa = +2.25V 259 384 Dropout Voltage (Note 1) I = 5mA = +2.8V 21 315 mv = +4.V 147 255 Line Regulation V LNR V I N fr om ( V OU T + 1m V ) to 5.5V, I L OA D = 5m A -.175 +.175 %/V Load Regulation V LDR I = 1mA to 5mA 35 p p m /m A SHUTDOWN Shutdown Supply Current I OFF SHDN = GND, V = 5.5V 5 µa SHDN Input Threshold V IH 2.5V < V < 5.5V 1.6 V IL 2.5V < V < 5.5V.6 V SHDN Input Bias Current I SHDN SHDN = GND or 1 na 3
5mA, Low-Voltage Linear Regulator in µmax ELECTRICAL CHARACTERISTICS (continued) (V = (SETPOT) + 5mV or V = +2.25V whichever is greater, SET = GND, SHDN =, T A = -4 C to +85 C, unless otherwise noted. Typical values are at T A = +25 C.) (Note 2) POWER-OK PARAMETER SYMBOL CONDITIONS M TYP MAX UNITS POK Output Low Voltage V OL Sinking 2mA 5 mv Operating Voltage Range for Valid POK Output Sinking 1µA 1. 5.5 V Output High-Leakage Current V POK = +5.5V 1 na Threshold Rising edge, referred to (NOMAL) 89 97 % Note 1: Dropout voltage is defined as V -, when is 1mV below the value of and when V = (NOM) +.5V. For 2.25V 4.V, dropout voltage limits are linearly interpolated from the values listed. For < 4.V, dropout voltage limit is equal to the value for = 4.V. Note 2: Specifications to -4 C are guaranteed by design, not production tested. Typical Operating Characteristics (EUA33, V = + 5mV, SHDN =, C = 1µF, C = 1µF, T A = +25 C, unless otherwise noted.) 3.5 3. PUT VOLTAGE vs. PUT VOLTAGE I = ma toc1 3.32 3.31 PUT VOLTAGE vs. LOAD CURRENT toc2 3.34 3.33 PUT VOLTAGE vs. TEMPERATURE V = + 5mV I = toc3 PUT VOLTAGE (V) 2.5 2. 1.5 1. I = 5mA PUT VOLTAGE (V) 3.3 3.29 3.28 3.27 PUT VOLTAGE (V) 3.32 3.31 3.3.5 3.26 3.29 1.5 2. 2.5 3. 3.5 4. 4.5 5. 5.5 PUT VOLTAGE (V) 6. 3.25 1 2 3 4 5 6 7 8 LOAD CURRENT (ma) 3.28-4 -15 1 35 6 85 TEMPERATURE ( C) DROP VOLTAGE (mv) 4 35 3 25 2 15 1 5 DROP VOLTAGE vs. LOAD CURRENT T A = +25 C T A = +85 C 1 2 3 4 5 6 7 8 LOAD CURRENT (ma) T A = -4 C toc4 DROP VOLTAGE (V).28.26.24.22.2.18.16 DROP VOLTAGE vs. PUT VOLTAGE.14 2. 2.5 3. 3.5 4. 4.5 PUT VOLTAGE (V) toc5 GROUND-P CURRENT (µa) 6 55 5 45 4 35 3 25 2 15 1 5 GROUND-P CURRENT vs. PUT VOLTAGE I = 5mA I = ma 2. 2.5 3. 3.5 4. 4.5 5. 5.5 6. PUT VOLTAGE (V) toc6 4
5mA, Low-Voltage Linear Regulator in µmax Typical Operating Characteristics (continued) (EUA33, V = + 5mV, SHDN =, C = 1µF, C = 1µF, T A = +25 C, unless otherwise noted.) GROUND-P CURRENT (µa) 5 45 4 35 3 25 2 15 1 GROUND-P CURRENT vs. LOAD CURRENT V = 5.5V V = 3.8V 1 2 3 4 5 6 7 8 LOAD CURRENT (A) toc7 GROUND-P CURRENT (µa) 2 19 18 17 16 15 GROUND-P CURRENT vs. TEMPERATURE V = + 5mV I = -4-15 1 35 6 85 TEMPERATURE ( C) toc8 PSRR (db) -6-5 -4-3 -2 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY -1 C = 1µF I = 5mA.1.1 1 1 1 1 FREQUENCY (khz) toc9 PUT SPECTRAL NOISE DENSITY (µv/ Hz) 1 1.1.1 PUT SPECTRAL NOISE DENSITY vs. FREQUENCY.1.1 1 1 1 1 FREQUENCY (khz) C = 1µF I = 5mA toc1 PUT NOISE DC TO 1MHz = 3.3V R = 66Ω (5mA) 2ms/div toc11 1mV/div REGION OF C ESR 1 1 1.1.1 REGION OF STABLE C ESR vs. LOAD CURRENT C = 1µF STABLE REGION 1 2 3 4 5 6 7 8 FREQUENCY (khz) toc12 LOAD-TRANSIENT RESPONSE toc13 V = + 5mV C = 1µF R = 66Ω TO 6.6Ω (5mA TO 5mA) 1µs/div I 2mA/div 2mV/div 5
5mA, Low-Voltage Linear Regulator in µmax Typical Operating Characteristics (continued) (EUA33, V = + 5mV, SHDN =, C = 1µF, C = 1µF, T A = +25 C, unless otherwise noted.) LOAD-TRANSIENT RESPONSE NEAR DROP toc14 I 2mA/div LE-TRANSIENT RESPONSE toc15 6V V 1V/div 3V 1µs/div V = + 1mV C = 1µF R = 66Ω TO 6.6Ω (5mA TO 5mA) 5mV/div 2µs/div 1mV/div SHUTDOWN WAVEFORM toc16 POK WAVEFORM toc17 2V V SHDN 1V/div 5V V 2V/div R = 6.6Ω (5mA) 3V 1V/div R = 66Ω (5mA) 2V/div V POK 2V/div 2µs/div 2µs/div Pin Description P NAME FUNCTION 1, 2 3 POK 4 SHDN 5 GND 6 SET 7, 8 Regulator Input. Supply voltage can range from +2.25V to +5.5V. Bypass with a 1µF capacitor to GND (see Capacitor Selection and Regulation Stability). Connect both input pins together externally. Open-Drain, Active-Low Power-OK Output. POK remains low while the output voltage ( ) is below the POK threshold. Connect a 1kΩ pullup resistor from POK to. Active-Low Shutdown Input. A logic low at SHDN reduces supply current to.2µa. In shutdown, the POK output is low. Connect SHDN to for normal operation. Ground. This pin and the exposed pad also function as a heatsink. Solder both to a large pad or to the circuit-board ground plane to maximize power dissipation. Voltage-Setting Input. Connect SET to GND for preset output. Connect an external resistive voltage-divider from to SET to set the output voltage between.8v and 4.5V. The SET regulation voltage is 8mV. Regulator Output. sources up to 5mA. Bypass with a 1µF low-esr capacitor to GND. Connect both pins together externally. 6
5mA, Low-Voltage Linear Regulator in µmax Detailed Description The is a low-dropout, low-quiescent-current linear regulator. The device supplies loads up to 5mA and is available with preset output voltages. As illustrated in Figure 1, the includes a.8v reference, error amplifier, P-channel pass transistor, and internal feedback voltage-divider. The reference is connected to the error amplifier, which compares it with the feedback voltage and amplifies the difference. If the feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled lower, which allows more current to pass to the output increasing the output voltage. If the feedback voltage is too high, the pass-transistor gate is pulled up, allowing less current to pass to the output. The output voltage is fed back through either an internal resistive voltage-divider connected to or an external resistor network connected to SET. The dualmode comparator examines V SET and selects the feedback path. If V SET is below 35mV, the internal feedback path is used, and the output is regulated to the factorypreset voltage. Additional blocks include an output current limiter, thermal sensor, and shutdown logic. Internal P-Channel Pass Transistor The features a.4ω P-channel MOSFET pass transistor. Unlike similar designs using PNP pass transistors, P-channel MOSFETs require no base drive, which reduces operating 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 does not suffer from these problems. Output Voltage Selection The 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 output voltage (see Selector Guide). For example, the EUA33 has a preset 3.3V output voltage. The output voltage may also be adjusted by connecting a voltage-divider from to SET (Figure 2). Select R2 in the 25kΩ to 1kΩ range. Calculate R1 with the following equation: R1 = R2 [( / V SET ) - 1] where V SET =.8V, and may range from.8v to 4.5V. Shutdown Drive SHDN low to enter shutdown. During shutdown, the output is disconnected from the input, and supply current drops to.2µa. When in shutdown, POK pulls low. The capacitance and load at determine the rate at which decays. SHDN can be pulled as high as +6V, regardless of the input and output voltage. Power-OK Output The POK output pulls low when is less than 93% of the nominal regulation voltage. Once exceeds 93% of the nominal voltage, POK goes high impedance. POK is an open-drain N-channel output. To obtain a logic voltage output, connect a pullup resistor from POK to. A 1kΩ resistor works well for most applications. POK can be used to signal a microcontroller (µc), or drive an external LED to indicate power failure. When the is shutdown, POK is held low independent of the output voltage. If unused, leave POK grounded or unconnected. Current Limit The monitors and controls the pass transistor s gate voltage, limiting the output current to 1.4A (typ). The output can be shorted to ground for an indefinite period of time without damaging the part. Thermal Overload Protection Thermal overload protection limits total power dissipation in the. When the junction temperature exceeds T J = +17 C, a thermal sensor turns off the pass transistor, allowing the device to cool. The thermal sensor turns the pass transistor on again after the junction temperature cools by 2 C, resulting in a pulsed output during continuous thermal overload conditions. Thermal overload protection protects the in the event of fault conditions. For continuous operation, do not exceed the absolute maximum junction-temperature rating of T J = +15 C. Operating Region and Power Dissipation The 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 = I (V - ). The maximum allowed power dissipation is 1.3W or: PMAX = (T J(MAX) - T A ) / (θ JC + θ CA ) where T J - T A is the temperature difference between the die junction and the surrounding air, θ JC is the thermal resistance from 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. The package features an exposed thermal pad on its underside. This pad lowers the package s thermal resistance by provid- 7
5mA, Low-Voltage Linear Regulator in µmax V +2.25V TO +5.5V C 1µF ON OFF SHDN SHUTDOWN LOGIC MOSFET DRIVER WITH I LIM V REF.8V THERMAL SENSOR PRESET MODE.8V TO 3.3V C 1µF LOGIC SUPPLY VOLTAGE ( ) ERROR AMPLIFIER R POK 1kΩ TO µc POK SET 93% V REF 8mV GND Figure 1. Functional Diagram ing a direct heat conduction path from the die to the PC board. Connect the exposed backside pad and GND to the system ground using a large pad or ground plane, or multiple vias to the ground plane layer. The delivers up to.5a(rms) and operates with input voltages up to 5.5V, but not simultaneously. High output currents can only be sustained when inputoutput differential is within the limits outlined. Applications Information Capacitor Selection and Regulator Stability Connect a 1µF capacitor between and ground and a 1µF low equivalent series resistance (ESR) capacitor between and ground. The input capacitor (C ) lowers the source impedance of the input supply. Reduce noise and improve load-transient response, stability, and power-supply rejection by using larger output capacitors. The output capacitor s (C ) ESR affects stability and output noise. Use output capacitors with an ESR of.1ω or less to ensure stability and optimum transient response. Surface-mount ceramic capacitors have very low ESR and are commonly available in values up to 1µF. Connect C and C as close to the as possible. Noise, PSRR, and Transient Response The is designed to operate with low dropout voltages and low quiescent currents, while still maintaining good noise, transient response, and AC rejection. See the Typical Operating Characteristics for a plot of Power-Supply Rejection Ratio (PSRR) vs. Frequency. When operating from noisy sources, improved supply-noise rejection and transient response can be achieved by increasing the values of the input and output bypass capacitors and through passivefiltering techniques. The load-transient 8
5mA, Low-Voltage Linear Regulator in µmax V +2.25V TO +5.5V ON OFF C 1µF SHDN SET C 1µF R1 = R2-1.8V R 1 R 2 MAXIMUM PUT CURRENT (A).8.7.6.5.4.3.2.1 CONTUOUS CURRENT LIMIT T A = +85 C T A = +7 C TYPICAL V DROP LIMIT POWER-µMAX PACKAGE OPERATG REGION AT T J(MAX) = +15 C T A = +5 C.5 1. 1.5 2. 2.5 3. 3.5 4. 4.5 5. PUT-PUT VOLTAGE DIFFERENTIAL (V) POK GND Figure 3. Power Operating Regions: Maximum Output Current vs. Supply Voltage Figure 2. Adjustable Output Using External Feedback Resistors response graphs (see Typical Operating Characteristics) show 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 overshoot for a step change in the load current from 5mA to 5mA is 4mV. 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 uses a P-channel MOSFET pass transistor, its dropout voltage is a function of drain-tosource on-resistance (R DS(ON) ) multiplied by the load current (see Typical Operating Characteristics): V DROP = V - = R DS(ON) I TRANSISTOR COUNT: 949 Chip Information 9
5mA, Low-Voltage Linear Regulator in µmax Package Information 8L, µmax, EXP PAD.EPS Note: The has on exposed thermal pad on the bottom side of the package. 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. 1 Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA 9486 48-737-76 21 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.