19-1257; Rev 1; 3/98 Low-Dropout, 120mA Linear Regulators For dual versions, refer to the MAX8865/MAX8866 data sheet. For low-noise versions with 30µVRMS output noise, refer to the MAX8877/MAX8878. ________________________Applications Cordless Telephones ____________________________Features ♦ LP2980 Pin-Compatible SOT23 Package ♦ Low, 55mV Dropout Voltage at 50mA IOUT (130mV at 120mA) ♦ Low, 73µA No-Load Supply Current Low, 82µA Operating Supply Current (even in dropout) ♦ Miniature External Components ♦ Thermal Overload Protection ♦ Output Current Limit ♦ Reverse Battery Protection ♦ Dual Mode Operation: Fixed or Adjustable (1.25V to 6.5V) Output ♦ Low-Power Shutdown ______________Ordering Information TEMP. RANGE PINPACKAGE SOT TOP MARK MAX8873TEUK-T -40°C to +85°C 5 SOT23-5 ABZH -40°C to +85°C 5 SOT23-5 ABZI MAX8873REUK-T -40°C to +85°C 5 SOT23-5 ABZL PART MAX8873SEUK-T Modems PCS Telephones Hand-Held Instruments MAX8874TEUK-T -40°C to +85°C 5 SOT23-5 ABZJ Cellular Telephones Palmtop Computers MAX8874SEUK-T -40°C to +85°C 5 SOT23-5 ABZK PCMCIA Cards Electronic Planners MAX8874REUK-T -40°C to +85°C 5 SOT23-5 ABZM __________Typical Operating Circuit __________________Pin Configuration TOP VIEW IN 1 OUT IN BATTERY CIN 1µF MAX8873 MAX8874 SHDN GND 5 OUT OUTPUT VOLTAGE COUT 1µF SET GND 2 MAX8873 MAX8874 SHDN 3 4 SET SOT23-5 Dual Mode is a trademark of Maxim Integrated Products. ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468. MAX8873T/S/R, MAX8874T/S/R _______________General Description The MAX8873T/S/R and MAX8874T/S/R low-dropout linear regulators operate from a +2.5V to +6.5V input range and deliver up to 120mA. A PMOS pass transistor allows the low, 82µA supply current to remain independent of load, making these devices ideal for battery-operated portable equipment such as cellular phones and cordless phones. The devices feature Dual Mode™ operation: their output voltage is preset (at 3.15V for the T versions, 2.84V for the S versions, or 2.80V for the R versions) or can be adjusted with an external resistor divider. Total error on the output is ±3.5%. Output voltages are set on the low side of popular ranges so that power drain is minimized for longer battery life. Other features include low-power shutdown, short-circuit protection, thermal shutdown protection, and reverse battery protection. The MAX8874 also includes an auto-discharge function, which actively discharges the output voltage to ground when the device is placed in shutdown mode. Both devices come in a miniature 5-pin SOT23 package. MAX8873T/S/R, MAX8874T/S/R Low-Dropout, 120mA Linear Regulators ABSOLUTE MAXIMUM RATINGS VIN to GND ..................................................................-7V to +7V Output Short-Circuit Duration ............................................Infinite SET to GND ..............................................................-0.3V to +7V SHDN to GND..............................................................-7V to +7V SHDN to IN .................................................................-7V to 0.3V OUT to GND ................................................-0.3V to (VIN + 0.3V) Continuous Power Dissipation (TA = +70°C) SOT23-5 (derate 7.1mW/°C above +70°C) .................571mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C θJA ..................................................................................140°C/W Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+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 = +3.6V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Input Voltage (Note 2) Output Voltage Adjustable Output Voltage Range (Note 3) SYMBOL CONDITIONS MIN VIN VOUT 0mA ≤ IOUT ≤ 50mA, SET = GND Ground Pin Current MAX UNITS 6.5 V MAX887_T 3.05 3.15 3.25 MAX887_S 2.75 2.84 2.93 MAX887_R 2.70 2.80 2.88 VOUT VSET Maximum Output Current Current Limit (Note 4) TYP 2.5 6.5 120 ILIM IQ Dropout Voltage (Note 5) IOUT = 0mA 73 IOUT = 50mA 82 150 1.1 IOUT = 50mA 55 120 0 0.15 SET = GND 0.011 0.030 SET tied to OUT 0.006 ∆VLNR VIN = 2.5V to 6.5V, SET tied to OUT, IOUT = 1mA Load Regulation ∆VLDR IOUT = 0mA to 50mA Output Voltage Noise mA IOUT = 1mA Line Regulation 10Hz to 1MHz -0.15 V mA 280 SET = GND V COUT = 1µF 350 COUT = 100µF 220 µA mV %/V %/mA µVRMS SHUTDOWN SHDN Input Threshold VIH SHDN Input Bias Current ISHDN Shutdown Supply Current IQSHDN Shutdown Discharge Resistance (MAX8874) 2 2.0 VIL 0.4 V SHDN = VIN VOUT = 0V TA = +25°C 0 TA = TMAX 0.05 TA = +25°C 0.0001 TA = TMAX 0.02 300 _______________________________________________________________________________________ 100 1 V nA µA Ω Low-Dropout, 120mA Linear Regulators (VIN = +3.6V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX TA = +25°C 1.225 1.25 1.275 TA = TMIN to TMAX 1.215 1.25 1.285 TA = +25°C 0.015 2.5 TA = TMAX 0.5 UNITS SET INPUT SET Reference Voltage (Note 3) VSET VIN = 2.5V to 6.5V, IOUT = 1mA SET Input Leakage Current (Note 3) ISET VSET = 1.3V V nA THERMAL PROTECTION Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSHDN 170 °C ∆TSHDN 20 °C Note 1: Limits are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control (SQC) methods. Note 2: Guaranteed by line-regulation test. Note 3: Adjustable mode only. Note 4: For design purposes, the current limit should be considered 120mA minimum to 420mA maximum. Note 5: The dropout voltage is defined as (VIN - VOUT) when VOUT is 100mV below the value of VOUT for VIN = VOUT + 2V. __________________________________________Typical Operating Characteristics (VIN = +3.6V, CIN = 1µF, COUT = 1µF, MAX887_T, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. LOAD CURRENT 3.5 MAX8873/74-02 3.25 95 3.0 3.20 3.15 3.10 OUTPUT VOLTAGE (V) 90 SUPPLY CURRENT (µA) OUTPUT VOLTAGE (V) 100 MAX8873/74-01 3.30 OUTPUT VOLTAGE vs. INPUT VOLTAGE MAX8873/74-03 OUTPUT VOLTAGE vs. LOAD CURRENT 85 80 75 70 65 60 3.05 50 0 20 40 60 80 LOAD CURRENT (mA) 100 120 2.0 NO LOAD 1.5 1.0 0.5 55 3.00 2.5 0 0 20 40 60 80 LOAD CURRENT (mA) 100 120 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) _______________________________________________________________________________________ 3 MAX8873T/S/R, MAX8874T/S/R ELECTRICAL CHARACTERISTICS (continued) ____________________________Typical Operating Characteristics (continued) (VIN = +3.6V, CIN = 1µF, COUT = 1µF, MAX887_T, TA = +25°C, unless otherwise noted.) OUTPUT VOLTAGE vs. TEMPERATURE 70 ILOAD = 0mA 60 50 40 30 20 100 MAX8863/4-06 3.25 OUTPUT VOLTAGE (V) ILOAD = 50mA 90 80 3.20 3.15 3.10 70 60 50 40 30 20 3.05 10 10 3.00 0 3 2 4 6 5 0 -40 7 -20 DROPOUT VOLTAGE vs. LOAD CURRENT 70 MAX8873/74-07 TA = +85°C 80 60 100 PSRR (dB) 80 TA = -40°C COUT = 10µF 40 30 COUT = 1µF 20 40 10 20 0 0 20 40 60 80 100 0 0.1 1 10 FREQUENCY (kHz) 100 100 COUT = 1µF COUT = 100µF 0.10 1000 0.1 1 10 OUTPUT NOISE DC TO 1MHz VOUT STABLE REGION 0.1 0.01 0 20 40 60 80 LOAD CURRENT (mA) 4 100 100 1 EXTERNAL FEEDBACK 1 80 RL = 50Ω INTERNAL FEEDBACK 10 60 10 MAX8873/74-8B COUT = 1µF 40 FREQUENCY (kHz) REGION OF STABLE COUT ESR vs. LOAD CURRENT 1000 20 0.01 0.01 120 LOAD CURRENT (mA) COUT ESR (Ω) -20 OUTPUT SPECTRAL NOISE DENSITY vs. FREQUENCY 50 TA = +25°C 0 -40 TEMPERATURE (°C) VOUT = 3.15V RL = 100Ω 60 120 60 40 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY 160 100 20 TEMPERATURE (°C) INPUT VOLTAGE (V) 140 0 OUTPUT SPECTRAL NOISE DENSITY (µV/√Hz) 1 MAX8873/74-08 0 MAX8873/74-8A SUPPLY CURRENT (µA) 80 ILOAD = 50mA SUPPLY CURRENT (µA) ILOAD = 50mA 90 3.30 MAX8873/74-04 100 SUPPLY CURRENT vs. TEMPERATURE MAX8873/74-05 SUPPLY CURRENT vs. INPUT VOLTAGE DROPOUT VOLTAGE (mV) MAX8873T/S/R, MAX8874T/S/R Low-Dropout, 120mA Linear Regulators 120 1ms/div ILOAD = 50mA, VOUT IS AC COUPLED _______________________________________________________________________________________ 100 1000 Low-Dropout, 120mA Linear Regulators (VIN = +3.6V, CIN = 1µF, COUT = 1µF, MAX887_T, TA = +25°C, unless otherwise noted.) LINE-TRANSIENT RESPONSE LOAD-TRANSIENT RESPONSE 3.16V 3.16V VOUT 3.15V VOUT 3.15V 3.14V 3.14V VIN 50mA 4.6V ILOAD 0mA 3.6V 50µs/div ILOAD = 50mA, VOUT IS AC COUPLED 10µs/div ILOAD = 0mA to 50mA, CIN = 10µF, VOUT IS AC COUPLED LOAD-TRANSIENT RESPONSE LOAD-TRANSIENT RESPONSE 3.16V 3.16V VOUT 3.15V VOUT 3.15V 3.14V 3.14V 50mA ILOAD 0mA 50mA ILOAD 0mA 10µs/div 10µs/div VIN = VOUT + 0.2V, ILOAD = 0mA to 50mA, CIN = 10µF, VOUT IS AC COUPLED VIN = VOUT + 0.1V, ILOAD = 0mA to 50mA, CIN = 10µF, VOUT IS AC COUPLED MAX8874 SHUTDOWN (NO LOAD) MAX8874 SHUTDOWN 4V VOUT 4V 2V VOUT 0V VSHDN 2V 0V 2V VSHDN 0V 2V 0V 500µs/div NO LOAD 200µs/div ILOAD = 50mA _______________________________________________________________________________________ 5 MAX8873T/S/R, MAX8874T/S/R ____________________________Typical Operating Characteristics (continued) MAX8873T/S/R, MAX8874T/S/R Low-Dropout, 120mA Linear Regulators ______________________________________________________________Pin Description PIN NAME FUNCTION 1 IN 2 GND Ground. This pin also functions as a heatsink. Solder to large pads or the circuit board ground plane to maximize thermal dissipation. 3 SHDN Active-Low Shutdown Input. A logic low reduces the supply current to 0.1nA. On the MAX8874, a logic low also causes the output voltage to discharge to GND. Connect to IN for normal operation. 4 SET Feedback Input for Setting the Output Voltage. Connect to GND to set the output voltage to the preset 2.80V (MAX887_R), 2.84V (MAX887_S), or 3.15V (MAX887_T). Connect to an external resistor divider for adjustable-output operation. DO NOT LEAVE THIS PIN UNCONNECTED. 5 OUT Regulator Output. Fixed or adjustable from 1.25V to 6.5V. Sources up to 120mA. Bypass with a 1µF, <0.2Ω typical ESR capacitor to GND. Regulator Input. Supply voltage can range from 2.5V to 6.5V. Bypass with 1µF to GND (see Capacitor Selection and Regulator Stability). _______________Detailed Description The MAX8873/MAX8874 are low-dropout, low-quiescentcurrent linear regulators designed primarily for batterypowered applications. They supply an adjustable 1.25V to 6.5V output or a preselected 2.80V (MAX887_R), 2.84V (MAX887_S), or 3.15V (MAX887_T) output for load currents up to 120mA. These devices consist of a 1.25V reference, error amplifier, MOSFET driver, P-channel pass transistor, dual-mode comparator, and internal feedback voltage divider (Figure 1). The 1.25V bandgap reference is connected to the error amplifier’s inverting input. The error amplifier compares this reference with the selected feedback voltage and amplifies the difference. The MOSFET driver reads the error signal IN SHDN and applies the appropriate drive to the P-channel pass transistor. If the feedback voltage is lower than the reference, the pass-transistor gate is pulled lower, allowing more current to pass and 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 resistor voltage divider connected to the OUT pin, or an external resistor network connected to the SET pin. The dual-mode comparator examines the SET voltage and selects the feedback path. If SET is below 60mV, internal feedback is used and the output voltage is regulated to the preset output voltage. Additional blocks include a current limiter, reverse battery protection, thermal sensor, and shutdown logic. REVERSE BATTERY PROTECTION ERROR AMP MAX8873 MAX8874 MOS DRIVER WITH ILIMIT P OUT SHUTDOWN LOGIC N * THERMAL SENSOR 1.25V REF DUAL-MODE COMPARATOR 60mV GND * AUTO-DISCHARGE, MAX8874 ONLY Figure 1. Functional Diagram 6 _______________________________________________________________________________________ SET Low-Dropout, 120mA Linear Regulators 3 CIN BATTERY 1µF OUT IN MAX8873 MAX8874 SHDN OUTPUT VOLTAGE 5 R1 20pF SET 4 COUT 1µF RL GND 2 R2 Shutdown Figure 2. Adjustable Output Using External Feedback Resistors Internal P-Channel Pass Transistor The MAX8873/MAX8874 feature a 1.1Ω typical P-channel MOSFET pass transistor. This provides several advantages over similar designs using PNP pass transistors, including longer battery life. The P-channel MOSFET requires no base drive current, which reduces quiescent current considerably. PNPbased regulators waste considerable amounts of current in dropout when the pass transistor saturates. They also use high base-drive currents under large loads. The MAX8873/MAX8874 do not suffer from these problems, and consume only 82µA of quiescent current, whether in dropout, light load, or heavy load applications (see Typical Operating Characteristics). Output Voltage Selection The MAX8873/MAX8874 feature Dual Mode operation: they operate in either a preset voltage mode or an adjustable mode. In preset voltage mode, internal, trimmed feedback resistors set the MAX887_R output to 2.80V, the MAX887_S output to 2.84V, and the MAX887_T output to 3.15V. Select this mode by connecting SET to ground. In adjustable mode, select an output between 1.25V and 6.5V using two external resistors connected as a voltage divider to SET (Figure 2). The output voltage is set by the following equation: VOUT = VSET (1 + R1 / R2) where VSET = 1.25V. To simplify resistor selection: V R1 = R2 OUT VSET − 1 A low input on the SHDN pin shuts down the MAX8873/MAX8874. In shutdown mode, the pass transistor, control circuit, reference, and all biases are turned off, reducing the supply current to typically 0.1nA. Connect SHDN to IN for normal operation. The MAX8874 output voltage is actively discharged to ground when the part is placed in shutdown (see Typical Operating Characteristics). Current Limit The MAX8873/MAX8874 include a current limiter that monitors and controls the pass transistor’s gate voltage, estimating the output current and limiting it to about 280mA. For design purposes, the current limit should be considered 120mA to 420mA. The output can be shorted to ground for an indefinite time period without damaging the part. Thermal Overload Protection Thermal overload protection limits total power dissipation in the MAX8873/MAX8874. When the junction temperature exceeds T J = +170°C, the thermal sensor sends a signal to 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 typically cools by 20°C, resulting in a pulsed output during continuous thermal overload conditions. Thermal overload protection is designed to protect the MAX8873/MAX8874 in the event of fault conditions. Stressing the device with high load currents and high input-output differential voltages (which result in die temperatures above +125°C) may cause a momentary overshoot (2% to 8% for 200ms) when the load is completely removed. This can be remedied by raising the minimum load current from 0µA (+125°C) to 100µA (+150°C). For continuous operation, do not exceed the absolute maximum junction temperature rating of TJ = +150°C. _______________________________________________________________________________________ 7 MAX8873T/S/R, MAX8874T/S/R 1 Choose R2 = 100kΩ to optimize power consumption, accuracy, and high-frequency power-supply rejection. The total current through the external resistive feedback and load resistors should not be less than 10µA. Since the VSET tolerance is typically less than ±25mV, the output can be set using fixed resistors instead of trim pots. Connect a 10pF to 25pF capacitor across R1 to compensate for layout-induced parasitic capacitances. In preset voltage mode, impedances between SET and ground should be less than 100kΩ. Otherwise, spurious conditions could cause the voltage at SET to exceed the 60mV dual-mode threshold. MAX8873T/S/R, MAX8874T/S/R Low-Dropout, 120mA Linear Regulators Operating Region and Power Dissipation Noise Maximum power dissipation of the MAX8873/MAX8874 depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of air flow. The power dissipation across the device is P = IOUT (VIN VOUT). The resulting maximum power dissipation is: PMAX = (TJ - TA) / θJA The MAX8873/MAX8874 exhibit 350µVRMS noise during normal operation. When using the MAX8873/MAX8874 in applications that include analog-to-digital converters (ADCs) of greater than 12 bits, consider the ADC’s power-supply rejection specifications (see the Output Noise DC to 1MHz photo in the Typical Operating Characteristics). For devices with lower output noise, refer to the MAX8877/MAX8878. where (TJ - TA) is the temperature difference between the MAX8873/MAX8874 die junction and the surrounding air, and θJA is the thermal resistance of the chosen package to the surrounding air. The GND pin of the MAX8873/MAX8874 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. Reverse Battery Protection The MAX8873/MAX8874 have a unique protection scheme that limits the reverse supply current to less than 1mA when either VIN or V SHDN falls below ground. The circuitry monitors the polarity of these two pins, disconnecting the internal circuitry and parasitic diodes when the battery is reversed. This feature prevents the device from overheating and damaging the battery. VIN > 5.5V Minimum Load Current When operating the MAX8873/MAX8874 with an input voltage above 5.5V, a minimum load current of 20µA is required to maintain regulation in preset voltage mode. When setting the output with external resistors, the minimum current through the external feedback resistors and load must be 30µA. __________Applications Information Capacitor Selection and Regulator Stability Normally, use a 1µF capacitor on the input and a 1µF capacitor on the output of the MAX8873/MAX8874. 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 several inches from the power source. Improve load-transient response, stability, and power-supply rejection by using large output capacitors. For stable operation over the full temperature range, with load currents up to 120mA, a minimum of 1µF is recommended. Power-Supply Rejection and Operation from Sources Other than Batteries The MAX8873/MAX8874 are designed to deliver low dropout voltages and low quiescent currents in batterypowered systems. Power-supply rejection is 62dB at low frequencies and rolls off above 300Hz. As the frequency increases above 20kHz, 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 values of the input and output capacitors, and by using passive filtering techniques (see the supply and load-transient responses in the Typical Operating Characteristics). Load-Transient Considerations The MAX8873/MAX8874 load-transient response graphs (see Typical Operating Characteristics) show two components of the output response: a DC shift of the output voltage due to the different load currents and the transient response. Typical overshoot for step changes in the load current from 0mA to 50mA is 14mV. Increasing the output capacitor’s value and decreasing its ESR attenuates transient spikes. Input-Output (Dropout) Voltage A regulator’s minimum input-output voltage differential (or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. Because the MAX8873/MAX8874 use a P-channel MOSFET pass transistor, their dropout voltage is a function of RDS(ON) multiplied by the load current (see Electrical Characteristics). ___________________Chip Information TRANSISTOR COUNT: 148 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. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.