19-4662; Rev 0; 6/09 Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator Features ♦ Space-Saving SC70 ♦ 25µVRMS Output Noise at 100Hz to 100kHz Bandwidth ♦ ♦ ♦ ♦ ♦ 65dB PSRR at 10kHz 120mV Dropout at 120mA Load Stable with 1µF Ceramic Capacitor for Any Load Guaranteed 120mA Output Output Voltages: 2.8V or 3V ♦ Low 40µA Ground Current ♦ Excellent Load/Line Transient ♦ Overcurrent and Thermal Protection Applications Cellular and Cordless Phones PDA and Palmtop Computers Base Stations Bluetooth Portable Radios and Accessories Wireless LANs Digital Cameras Personal Stereos Portable and Battery-Powered Equipment Ordering Information PART* TEMP RANGE PIN-PACKAGE MAX8940EXKxy-T -40°C to +85°C 5 SC70 MAX8940EXKxy+T -40°C to +85°C 5 SC70 *xy is the output voltage code (see Output Voltage Selector Guide). +Denotes a lead(Pb)-free/RoHS-compliant package. Output Voltage Selector Guide PART VOUT (V) MAX8940EXK28-T 2.8 AUE MAX8940EXK30-T 3 AUD Pin Configuration TOP MARK Typical Operating Circuit TOP VIEW 5 OUT IN 1 GND 2 CIN = 1µF ON OFF MAX8940 4 BP SHDN 3 INPUT 2V TO 6V IN OUT MAX8940 BP SHDN GND PRESET OUTPUT 2.8V OR 3.0V CBP = 10nF COUT = 1µF SC70 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX8940 General Description The MAX8940 low-noise, low-dropout (LDO) linear regulator is designed to deliver up to 120mA continuous output current. This regulator achieves a low 120mV dropout for 120mA load current. The MAX8940 uses an advanced architecture to achieve low output voltage noise of 25µVRMS and PSRR of 45dB at 100kHz. The MAX8940 is preset to either 2.8V or 3.0V. Designed with a p-channel MOSFET series pass transistor, the MAX8940 maintain very low ground current (40µA). The regulator is designed and optimized to work with lowvalue, low-cost ceramic capacitors. The MAX8940 requires only 1µF (typ) of output capacitance for stability with any load. When disabled, current consumption drops to below 1µA. Package is a 5-pin SC70. MAX8940 Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator ABSOLUTE MAXIMUM RATINGS IN to GND .................................................................-0.3V to +7V Output Short-Circuit Duration ............................................Infinite OUT, SHDN to GND ......................................-0.3V to (IN + 0.3V) FB, BP, N.C. to GND..................................-0.3V to (OUT + 0.3V) Continuous Power Dissipation (TA = +70°C) 5-Pin SC70 (derate 3.1mW/°C above +70°C) ..............0.247W θJA 5-Pin SC70 ................................................................324°C/W Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°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 (VIN = VOUT + 0.5V, TA = -40°C to +85°C, unless otherwise noted. CIN = 1µF, COUT = 1µF, CBP = 10nF. Typical values are at +25°C; the MAX8940 is tested with 2.45V output, unless otherwise noted.) (Note 1) PARAMETER Input Voltage Range SYMBOL CONDITIONS MAX UNITS 2.8 6 V IOUT = 1mA, TA = +25°C -1 +1 IOUT = 100µA to 80mA, TA = +25°C -2 +2 IOUT = 100µA to 80mA -3 +3 VIN Output Voltage Accuracy Maximum Output Current IOUT Current Limit ILIM Dropout Voltage (Note 2) MIN TYP 120 OUT = 90% of nominal value 130 mA 200 300 VOUT = 3V, IOUT = 80mA 80 170 VOUT = 3V, IOUT = 120mA 120 VOUT = 2.8V, IOUT = 80mA 90 VOUT = 2.8V, IOUT = 120mA 135 40 90 VIN = VOUT (nom) - 0.1V, IOUT = 0mA 220 500 IQ Line Regulation VLNR VIN = (VOUT + 0.5V) to 6V, IOUT = 0.1mA 0.001 Load Regulation VLDR IOUT = 1mA to 80mA 0.003 ISHDN Ripple Rejection PSRR 2 200 IOUT = 0.05mA Ground Current Shutdown Supply Current SHDN = 0V % TA = +25°C 0.003 TA = +85°C 0.05 f = 10kHz, IOUT = 10mA 65 f = 100kHz, IOUT = 10mA 45 _______________________________________________________________________________________ mA mV µA %/V %/mA 1 µA dB Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator (VIN = VOUT + 0.5V, TA = -40°C to +85°C, unless otherwise noted. CIN = 1µF, COUT = 1µF, CBP = 10nF. Typical values are at +25°C; the MAX8940 is tested with 2.45V output, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP Output Noise Voltage (RMS) f = 100Hz to 100kHz, ILOAD = 10mA 25 f = 100Hz to 100kHz, ILOAD = 80mA 13 Shutdown Exit Delay RLOAD = 50Ω (Note 3) SHDN Logic Low Level VIN = 2.8V to 6V SHDN Logic High Level VIN = 2.8V to 6V UNITS µV 300 µs 0.4 V 1.5 V TA = +25°C VIN = 6V, SHDN = 0V or 6V SHDN Input Bias Current MAX TA = +85°C µA 0.01 Thermal Shutdown 160 °C Thermal-Shutdown Hysteresis 10 °C Note 1: Limits are 100% tested at +25°C. Limits over operating temperature range are guaranteed by design. Note 2: Dropout is defined as VIN - VOUT when VOUT is 100mV below the value of VOUT for VIN = VOUT + 0.5V. Note 3: Time needed for VOUT to reach 90% of final value. Typical Operating Characteristics (VIN = VOUT + 0.5V, CIN = 1µF, COUT = 1µF, CBP = 10nF, TA = +25°C, unless otherwise noted.) 0.4 0.8 IOUT = 120mA 1.0 % DEVIATION (%) % DEVIATION (%) 1.5 0.2 0 -0.2 0.5 -0.4 0.0 -0.6 IOUT = 1mA 0.6 IOUT = 0mA 2.0 MAX8940 toc03 1.0 MAX8940 toc02 2.5 OUTPUT VOLTAGE (V) 0.6 MAX8940 toc01 3.0 OUTPUT VOLTAGE ACCURACY vs. TEMPERATURE OUTPUT VOLTAGE ACCURACY vs. LOAD CURRENT OUTPUT VOLTAGE vs. INPUT VOLTAGE 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 0 1 2 3 4 INPUT VOLTAGE (V) 5 6 -1.0 0 20 40 60 80 LOAD CURRENT (mA) 100 120 -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX8940 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VIN = VOUT + 0.5V, CIN = 1µF, COUT = 1µF, CBP = 10nF, TA = +25°C, unless otherwise noted.) 90 60 TA = -40°C IOUT = 120mA 300 250 200 150 100 30 IOUT = 0mA 50 0 20 40 60 80 100 120 160 VIN = 3.8V 120 80 40 0 0 1 LOAD CURRENT (mA) 2 3 4 5 0 20 40 INPUT VOLTAGE (V) MAX8940 toc08 MAX8940 toc07 90 80 70 45 PSRR (dB) 60 40 50 40 30 35 20 ILOAD = 10mA CBP = 10nF 10 30 0 -15 10 35 60 85 0.01 0.1 1 10 100 1000 TEMPERATURE (°C) FREQUENCY (kHz) OUTPUT NOISE OUTPUT NOISE SPECTRAL DENSITY vs. FREQUENCY MAX8940 toc09 VIN = 3.8V ILOAD = 10mA VNOISE = 25µVRMS MAX8940 toc10 1.E+04 OUTPUT NOISE DENSITY (nV/√Hz) -40 1.E+03 1.E+02 20µV/div 400µs/div 1.E+01 0.01 0.1 1 10 100 1000 FREQUENCY (kHz) 4 60 80 LOAD CURRENT (mA) PSRR vs. FREQUENCY GROUND PIN CURRENT vs. TEMPERATURE 50 GROUND PIN CURRENT (µA) VIN = 5.5V 200 0 0 MAX8940 toc 06 MAX8940 toc05 240 GROUND PIN CURRENT (µA) TA = +25°C 350 GROUND PIN CURRENT (µA) MAX8940 toc04 TA = +85°C 120 GROUND PIN CURRENT vs. LOAD CURRENT GROUND PIN CURRENT vs. INPUT VOLTAGE DROPOUT VOLTAGE vs. LOAD CURRENT 150 DROPOUT VOLTAGE (mV) MAX8940 Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator _______________________________________________________________________________________ 100 120 Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator (VIN = VOUT + 0.5V, CIN = 1µF, COUT = 1µF, CBP = 10nF, TA = +25°C, unless otherwise noted.) MAX8940 toc13 MAX8940 toc12 MAX8940 toc11 25 20 VIN = 3.1V ILOAD = 0 TO 50mA VOUT = 3V VIN = 3.5V ILOAD = 0 TO 50mA 15 10 VOUT 10mV/div VOUT 10mV/div 5 0 10 1ms/div 1ms/div 100 BP CAPACITANCE (nF) LINE TRANSIENT RESPONSE MAX8940 toc14 VIN = 3.5V TO 4V ENTERING SHUTDOWN DELAY EXITING SHUTDOWN WAVEFORM MAX8940 toc16 MAX8940 toc15 CBP = 0.01µF VOUT = 2.8V VOUT = 2.8V RLOAD = 47Ω SHUTDOWN VOLTAGE SHUTDOWN VOLTAGE OUTPUT VOLTAGE 2V/div OUTPUT VOLTAGE 2V/div VOUT 2mV/div 40µs/div 20µs/div 200µs/div REGION OF STABLE COUT ESR vs. LOAD CURRENT SHUTDOWN EXIT DELAY MAX8940 toc17 100 MAX8940 toc18 1 VOUT = 3V CBP = 100nF VOUT 1V/div SHUTDOWN VOLTAGE 10 COUT ESR (Ω) OUTPUT NOISE (µV) LOAD TRANSIENT RESPONSE NEAR DROPOUT LOAD TRANSIENT RESPONSE OUTPUT NOISE vs. BP CAPACITANCE 1 0.1 STABLE REGION 0.01 20µs/div 0 20 40 60 80 100 120 LOAD CURRENT (mA) _______________________________________________________________________________________ 5 MAX8940 Typical Operating Characteristics (continued) Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator MAX8940 Pin Description PIN NAME FUNCTION 1 IN 2 GND Unregulated Input Supply Ground 3 SHDN Shutdown. Pull low to disable the regulator. 4 BP Noise Bypass for Low-Noise Operation. Connect a 10nF capacitor from BP to OUT. It is short to OUT in shutdown mode. 5 OUT Regulated Output Voltage. Bypass with a capacitor to GND. See the Capacitor Selection and Regulator Stability section for more details. Detailed Description The MAX8940 is a low-noise, low-dropout, low-quiescent current linear regulator designed for spacerestricted applications. The part is available with preset output voltages 2.8V or 3.0V. This device can supply loads up to 120mA. As shown in the Functional Diagram , the MAX8940 consist of an innovative bandgap core and noise bypass circuit, error amplifier, p-channel pass transistor, and internal feedback voltage-divider. The 1.225V bandgap reference is connected to the error amplifier’s inverting input. The error amplifier compares this reference with the feedback voltage and amplifies the difference. If the feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled low. This allows more current to pass to the output and increases the output voltage. If the feedback voltage is too high, the pass transistor gate is pulled high, allowing less current to pass to the output. The output voltage is fed back through an internal resistor voltage-divider connected to the OUT pin. An external bypass capacitor connected to BP reduces noise at the output. Additional blocks include a current limiter, thermal sensor, and shutdown logic. Internal P-Channel Pass Transistor The MAX8940 features a 1Ω (typ) p-channel MOSFET pass transistor. This provides seve-ral advantages over similar designs using a PNP pass transistor, including longer battery life. The p-channel MOSFET requires no base drive, which considerably reduces quiescent current. PNP-based regulators waste considerable current in dropout when the pass transistor saturates. They also use high base-drive current under heavy loads. The MAX8940 does not suffer from these problems and 6 consume only 40µA of quiescent current in light load and 220µA in dropout (see the Typical Operating Characteristics). Shutdown The MAX8940 features a low-power shutdown mode that reduces quiescent current less than 1µA. Driving SHDN low disables the voltage reference, error amplifier, gatedrive circuitry, and pass transistor (see the Functional Diagram), and the device output enters a high-impedance state. Connect SHDN to IN for normal operation. Current Limit The MAX8940 includes a current limiter, which monitors and controls the pass transistor’s gate voltage, limiting the output current to 200mA. For design purposes, consider the current limit to be 130mA (min) to 300mA (max). The output can be shorted to ground for an indefinite amount of time without damaging the part. Thermal-Overload Protection Thermal-overload protection limits total power dissipation in the MAX8940. When the junction temperature exceeds TJ = +160°C, the thermal sensor signals the shutdown logic, turning off the pass transistor and allowing the IC to cool down. The thermal sensor turns the pass transistor on again after the IC’s junction temperature drops by 10°C, resulting in a pulsed output during continuous thermal-overload conditions. Thermal-overload protection is designed to protect the MAX8940 in the event of a fault condition. For continual operation, do not exceed the absolute maximum junction temperature rating of TJ = +150°C. Operating Region and Power Dissipation The MAX8940 maximum power dissipation depends on the thermal resistance of the case and circuit board, _______________________________________________________________________________________ Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator where TJ - TA is the temperature difference between the MAX8940 die junction and the surrounding air, θJC is the thermal resistance of the package, and θCA is the thermal resistance through the PC board, copper traces, and other materials to the surrounding air. The GND pin of the MAX8940 performs the dual function of providing an electrical connection to ground and channeling heat away. Connect the GND pin to ground using a large pad or ground plane. ESR variation with temperature. With dielectrics such as Z5U and Y5V, it may be necessary to use a 2.2µF or larger output capacitor to ensure stability at temperatures below -10°C. With X7R or X5R dielectrics, 1µF is sufficient at all operating temperatures. A graph of the region of stable COUT ESR vs. load current is shown in the Typical Operating Characteristics. Use a 0.01µF bypass capacitor at BP for low-output voltage noise. The leakage current going into the BP pin should be less than 10nA. Increasing the capacitance slightly decreases the output noise. Values above 0.1µF and below 0.001µF are not recommended. Noise, PSRR, and Transient Response Noise Reduction The MAX8940 is designed to deliver low noise and high PSRR, as well as low dropout and low quiescent currents in battery-powered systems. The MAX8940 power-supply rejection is 65dB at 1kHz. For the MAX8940, an external 0.01µF bypass capacitor between BP and OUT with innovative noise bypass scheme reduces output noises dramatically, exhibiting 25µVRMS of output voltage noise with CBP = 0.01µF and COUT = 1µF. Startup time is minimized by a poweron circuit that precharges the bypass capacitor. When operating from sources other than batteries, improved supply-noise rejection and transient response can be achieved by increasing the values of the input and output bypass capacitors, and through passive filtering techniques. The Typical Operating Characteristics show the MAX8940 line- and load-transient responses. Applications Information Capacitor Selection and Regulator Stability Use a 1µF capacitor on the MAX8940 input and a 1µF capacitor on the output. Larger input capacitor values and lower ESRs provide better noise rejection and linetransient response. Reduce output noise and improve load-transient response, stability, and power-supply rejection by using large output capacitors. Note that some ceramic dielectrics exhibit large capacitance and Dropout Voltage A regulator’s minimum dropout voltage determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the MAX8940 uses a p-channel MOSFET pass transistor, the dropout voltage is a function of drainto-source on-resistance (RDS(ON)) multiplied by the load current (see the Typical Operating Characteristics). Chip Information TRANSISTOR COUNT: 284 PROCESS: BiCMOS _______________________________________________________________________________________ 7 MAX8940 the temperature difference between the die junction and ambient, and the rate of airflow. The power dissipation across the device is: P = IOUT (VIN - VOUT) The maximum power dissipation is: PMAX = (TJ - TA)/(θJC + θCA) Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator MAX8940 Functional Diagram IN SHDN SHUTDOWN AND POWER-ON CONTROL MAX8940 ERROR AMP MOS DRIVER WITH ILIMIT P OUT THERMAL SENSOR 1.225V REFERENCE AND NOISE BYPASS GND BP 8 _______________________________________________________________________________________ Low-Noise, High PSRR, Low-Dropout, 120mA Linear Regulator PACKAGE CODE DOCUMENT NO. 5 SC70 X5-1 21-0076 SC70, 5L.EPS PACKAGE TYPE PACKAGE OUTLINE, 5L SC70 21-0076 E 1 1 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 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX8940 Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.