19-1783; Rev 1; 11/03 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 The MAX1735 negative-output, low-dropout linear regulator operates from a -2.5V to -6.5V input and delivers a guaranteed 200mA with a low 80mV dropout. The highaccuracy (±1%) output voltage is preset or can be adjusted from -1.25V to -5.5V with an external resistive voltage-divider. An internal N-channel MOSFET allows for a low 85µA quiescent current virtually independent of the load, making this device ideal for battery-powered portable equipment, such as PDAs, mobile phones, cordless phones, and wireless data modems. The device is available in several preset output voltage versions: -5.0V, -3.0V, and -2.5V. All versions offer a 1nA low-power shutdown mode, short-circuit protection, and thermal overload protection. The device is offered in a tiny 5-pin SOT23 package. Features ♦ Guaranteed 200mA Output Current ♦ Low 80mV Dropout Voltage at 200mA ♦ Low 85µA Quiescent Supply Current ♦ Low 1nA Current Shutdown Mode ♦ Stable with 1µF COUT ♦ PSRR >60dB at 100Hz ♦ Thermal Overload Protection ♦ Short-Circuit Protection ♦ -5.0V, -3.0V, or -2.5V Output Voltage or Adjustable (-1.25V to -5.5V) ♦ Tiny SOT23-5 Package Applications Ordering Information Disk Drives PART Modems PINPACKAGE TEMP RANGE Instrumentation Amplifiers MAX1735EUK50-T -40°C to +85°C 5 SOT23-5 Notebook Computers MAX1735EUK30-T -40°C to +85°C 5 SOT23-5 Mobile and Cordless Telephones MAX1735EUK25-T -40°C to +85°C 5 SOT23-5 PCMCIA Cards Output-Voltage Selector Guide GaAsFET Bias Mobile Wireless Data Modems PRESET OUTPUT VOLTAGE PART PDAs and Palmtop Computers MAX1735EUK50-T -5.0V or adj ADOZ MAX1735EUK30-T -3.0V or adj ADOY MAX1735EUK25-T -2.5V or adj ADOX Pin Configuration Typical Operating Circuit -5V, -3V, OR -2.5V OUTPUT UP TO 200mA -6.5V TO -2.5V INPUT OUT IN CIN COUT MAX1735 SOT TOP MARK TOP VIEW GND 1 IN 2 5 OUT 4 SET MAX1735 ON GND OFF ON SET SHDN SHDN 3 GND SOT23-5 ________________________________________________________________ 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 MAX1735 General Description MAX1735 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 ABSOLUTE MAXIMUM RATINGS IN, SET to GND .................................................... -7.0V to +0.3V SHDN to GND ............................................ (VIN - 0.3)V to +7.0V OUT to GND ...............................................(VIN - 0.3)V to +0.3V Output Short-Circuit Duration ........................................Indefinite Continuous Power Dissipation (TA = +70°C) 5-Pin SOT23 (derate 7.1mW/°C above +70°C)........... 571mW 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 (Circuit of Figure 2, VIN = VOUT - 1V, V SHDN = VIN, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Input Voltage SYMBOL CONDITIONS VIN Output Voltage Accuracy MIN Maximum Output Current IOUT Current Limit ILIM Ground-Pin Current IQ Dropout Voltage (Note 2) +1 IOUT = -100µA, TA = 0°C to +85°C -2 +2 ILOAD = -100µA to -200mA -3 +2 -1.225 Circuit of Figure 3, ILOAD = -100µA to -200mA -1.275 -1.2125 VOUT = 0 -1020 IOUT = -100µA -180 -200 -85 40 IOUT = -200mA 80 240 0 +0.15 f = 100Hz TA = +25°C -1 Shutdown Supply Current V SHDN = 0 SHDN Input High Threshold (Note 3) Negative voltage at SHDN -1.6 Positive voltage at SHDN +0.4 TA = +85°C %/mA µVRMS 60 dB -0.001 TA = +25°C Thermal Shutdown Junction Temperature Hysteresis = 15°C (typ) -0.4 -15 V SHDN = +6.5V V SHDN = 0, -6.5V µA +1.6 Negative voltage at SHDN SHDN Input Bias Current %/V 160 -1 -100 mV 0.004 Positive voltage at SHDN VSET = -1.25V, TA = +25°C mA µA IOUT = -100mA 10Hz to 1MHz, COUT = 1µF ISET -250 -125 IOUT from 0mA to -200mA V mA -515 IOUT = -200mA -0.15 % -1.2375 -1.275 Output Voltage Noise Set Input Bias Current -1.25 Circuit of Figure 3, IOUT = -100µA, TA = 0°C to +85°C Load Regulation SHDN Input Low Threshold (Note 3) V -2.5 -1 Circuit of Figure 3, VIN from -6.5V to -2.5V, VOUT = -1.25V PSRR UNITS -6.5 Line Regulation Power-Supply Rejection Ratio MAX TA = +25°C, IOUT = -100µA Circuit of Figure 3, TA = +25°C, IOUT = -100µA -1.2625 SET Regulation Set Point TYP +0.5 160 V nA 3.5 -0.5 V µA °C Note 1: Limits are 100% production tested at TA = +25°C. Limits over operating temperature range are guaranteed by design. Note 2: The dropout voltage is defined as VOUT - VIN, when VOUT is 100mV above the nominal value of VOUT. Note 3: The SHDN logic input can be driven by either a positive voltage or a negative voltage. | V SHDN | < 0.4V puts the device in shutdown, while | V SHDN | > 1.6V enables the device. 2 _______________________________________________________________________________________ 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. LOAD CURRENT 130 SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 140 120 100 80 60 MAX1735 toc02 ILOAD = 200mA 160 140 MAX1735 toc01 180 120 110 100 90 40 80 20 0 70 -1 -2 -3 -4 -5 -6 20 40 60 80 100 120 140 160 180 200 LOAD CURRENT (mA) SUPPLY CURRENT vs. TEMPERATURE DROPOUT VOLTAGE vs. LOAD CURRENT 140 120 100 80 NO LOAD 60 100 MAX1735 toc03 ILOAD = 200mA VOUT = -2.9V DROPOUT VOLTAGE (mV) SUPPLY CURRENT (µA) 0 SUPPLY VOLTAGE (V) 180 160 -7 MAX1735 toc04 0 40 80 TA = +25°C 60 TA = +85°C 40 TA = -40°C 20 20 0 0 -15 10 35 60 0 50 75 100 125 150 175 200 LOAD CURRENT (mA) OUTPUT VOLTAGE CHANGE vs. LOAD CURRENT OUTPUT VOLTAGE CHANGE vs. TEMPERATURE -0.4 TA = -40°C TA = +85°C -0.8 TA = +25°C -1.0 MAX1735 toc06 -0.2 1.00 0.75 OUTPUT VOLTAGE CHANGE (%) VOUT = -3V -0.6 25 TEMPERATURE (°C) 0 OUTPUT VOLTAGE CHANGE (%) 85 MAX1735 toc05 -40 0.50 ILOAD = 200mA 0.25 0 -0.25 NO LOAD -0.50 -0.75 -1.2 -1.00 0 25 50 75 100 125 150 175 200 LOAD CURRENT (mA) -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX1735 Typical Operating Characteristics (Circuit of Figure 2, VIN = -4.0V, VOUT = -3.0V, TA = +25°C, unless otherwise specified.) Typical Operating Characteristics (continued) (Circuit of Figure 2, VIN = -4.0V, VOUT = -3.0V, TA = +25°C, unless otherwise specified.) 50 COUT = 10µF 40 30 COUT = 1.0µF MAX1735 toc09 MAX1735 toc08 60 10 OUTPUT NOISE (µVRMS/√Hz) MAX1735 toc07 70 20 OUTPUT NOISE (10Hz TO 1MHz) OUTPUT NOISE DENSITY vs. FREQUENCY POWER-SUPPLY REJECTION RATIO vs. FREQUENCY PSRR (dB) 500µV/div COUT = 1µF ILOAD = 50mA 1 0.1 10 0.01 0 1 10 100 1k 10k 100k 10 1M 1k TIME (1ms/div) 100k FREQUENCY (Hz) FREQUENCY (Hz) REGION OF STABLE ESR vs. LOAD CURRENT LINE-TRANSIENT RESPONSE MAX1735 toc11 MAX1735 toc10 100 COUT = 1µF REGION OF STABLE ESR COUT (Ω) MAX1735 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 10 VOUT 50mV/div 1 0.1 VIN 1V/div REGION OF STABILITY 0.01 0.001 0 TIME (100µs/div) 20 40 60 80 100 120 140 160 180 200 LOAD CURRENT (mA) LOAD-TRANSIENT RESPONSE (NORMAL OPERATION) LOAD-TRANSIENT RESPONSE (NEAR DROPOUT) MAX1735 toc12 TIME (100µs/div) 4 MAX1735 toc13 ILOAD STEP 0 to 50mA ILOAD STEP 0 to 50mA VOUT 10mV/div VOUT 10mV/div TIME (100µs/div) _______________________________________________________________________________________ 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 SHUTDOWN RESPONSE (DRIVEN BY A NEGATIVE VOLTAGE) SHUTDOWN-PIN BIAS CURRENT vs. SHUTDOWN-PIN VOLTAGE MAX1735 toc14b VSHDN 2V/div 0 0 VSHDN 2V/div 0 VOUT 2V/div 0 VOUT 2V/div 1.5 1.0 0.5 MAX1735 toc15 SHUTDOWN-PIN BIAS CURRENT (µA) 2.0 INVALID LOGIC VOLTAGE MAX1735 toc14a INVALID LOGIC VOLTAGE SHUTDOWN RESPONSE (DRIVEN FROM A POSITIVE VOLTAGE) 0 -0.5 TIME (200µs/div) TIME (200µs/div) -6.5 -5.0 -3.5 -2.0 -0.5 1.0 2.5 4.0 5.5 SHUTDOWN-PIN VOLTAGE (V) Pin Description PIN NAME FUNCTION 1 GND 2 IN Regulator Input. Supply voltage can range from -2.5V to -6.5V. Bypass with a 1µF capacitor to GND (see Capacitor Selection and Regulator Stability). This pin also functions as a heatsink. Solder to a large PC board pad or directly to the PC board power plane to maximize thermal dissipation. 3 SHDN Shutdown Input. Drive SHDN to GND to turn the regulator off, reducing the input current to less than 1nA. Drive SHDN above +1.6V or below -1.6V to enable the regulator. Connect SHDN to IN for always-on operation. 4 SET Dual Mode™ Regulator Feedback Input. Connect SET to GND for the preset output voltage. Use a resistive voltage-divider from OUT to SET to set the output voltage between -1.25V and -5.5V. Regulation setpoint is -1.25V. 5 OUT Regulator Output. OUT supplies up to 200mA in regulation. Bypass to GND with a 1µF ceramic capacitor. Ground Dual Mode is a trademark of Maxim Integrated Products, Inc. _______________________________________________________________________________________ 5 MAX1735 Typical Operating Characteristics (continued) (Circuit of Figure 2, VIN = -4.0V, VOUT = -3.0V, TA = +25°C, unless otherwise specified.) MAX1735 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 IN THERMAL SENSOR CIN SHUTDOWN LOGIC NMOS PASS TRANSISTOR OUT ON GND SHDN OFF MAX1735 ON COUT ERROR AMPLIFIER R1 VREF -1.25V SET Dual Mode COMPARATOR R2 -270mV GND Figure 1. Functional Diagram Detailed Description The MAX1735 is a low-dropout negative linear voltage regulator. It features Dual Mode operation, allowing a fixed -5.0V, -3.0V, or -2.5V output voltage or an adjustable output from -1.25V to -5.5V. The regulator is guaranteed to supply 200mA of output current. It features 60dB power-supply rejection for noise-sensitive applications and a low 85µA operating current that optimizes it for battery-operated devices. As Figure 1 illustrates, the device consists of an internal -1.25V reference, an error amplifier, an N-channel MOSFET, an internal precision-trimmed feedback voltage-divider, and a Dual Mode comparator. The -1.25V reference is connected to the inverting input of the error amplifier. The error amplifier compares the reference voltage with the selected feedback voltage and amplifies the difference. The error amplifier drives the MOSFET to control the output voltage. The feedback voltage for regulation is generated by either an internal or external resistive voltage-divider connected from OUT to SET. The internal Dual Mode 6 comparator selects the feedback path based on VSET. Connect SET to GND to use the internal feedback path, setting the output voltage to the preset value. If an external voltage-divider is used, see Output Voltage Selection. Internal N-Channel MOSFET The MAX1735 features an N-channel MOSFET pass transistor. Unlike similar designs using NPN bipolar pass transistors, N-channel MOSFETs require extremely low drive currents, reducing overall quiescent current. Also, NPN-based regulators consume still more base current in dropout conditions when the pass transistor saturates. The MAX1735 does not suffer from these problems, consuming only 125µA total current at full load and in dropout. Output Voltage Selection The MAX1735 features Dual Mode operation, allowing for a preset or adjustable output voltage. In preset voltage mode, the output of the MAX1735 is set to -5.0V, -3.0V, or -2.5V (see Ordering Information). Select this mode by connecting SET to GND (Figure 2). _______________________________________________________________________________________ 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 OUT IN CIN 1µF CERAMIC COUT 1µF CERAMIC MAX1735 -6.5V TO -2.5V INPUT -5.5V TO -1.25V ADJUSTABLE OUTPUT -6.5V TO -2.5V INPUT -5.0V,-3.0V, OR -2.5V FIXED OUTPUT OUT IN CIN 1µF CERAMIC R1 COUT 1µF CERAMIC MAX1735 MAX1735 ON ON GND OFF ON GND SET SHDN OFF ON SET SHDN GND GND R2 VOUT = VSET Figure 2. Typical Application Circuit with Preset Output Voltage In adjustable mode, an output voltage between -5.5V and -1.25V is selected using two external resistors connected as a voltage-divider from OUT to SET (Figure 3). The output voltage is determined by the following equation: R1 VOUT = VSET 1 + R2 where VSET = VREFERENCE = -1.25V when in regulation. Since the input bias current at SET is <100nA, use large resistance values for R1 and R2 to minimize power consumption in the feedback network. A typical value of 100kΩ for R2 is acceptable for most applications. Higher values consume less current at the expense of output voltage accuracy. The above equation solved for R1 is: V R1 = R2 OUT − 1 VSET For preset output voltage mode, connect SET directly to GND. Shutdown In shutdown, the N-channel MOSFET, control circuitry, reference, and all internal circuits are turned off, reducing supply current to typically 1nA. SHDN can be driven by either a positive or negative voltage. Drive SHDN above +1.6V or below -1.6V to turn the regulator on. To turn the regulator off, drive SHDN to GND. For always-on operation, connect SHDN to IN. By including a positive threshold at SHDN, it can be driven by a standard 5V TTL level without needing level-shifting circuitry. (1 + R1R2) Figure 3. Typical Application Circuit with Adjustable Output Voltage Current Limiting The MAX1735 features a current limit that protects the regulator. Short-circuit output current is typically 515mA. The output will withstand a short to ground indefinitely; however, if the increased power dissipation heats the die to +160°C, the thermal overload protection will shut off the regulator, preventing damage to the IC. Thermal Overload Protection The thermal overload protection circuit protects the regulator against overheating due to prolonged overload conditions. When the die temperature exceeds +160°C, an on-chip thermal sensor disables the pass transistor, allowing the IC to cool. The thermal sensor reenables the pass MOSFET once the die temperature drops 15°C. A continuous short-circuit fault condition results in a cyclical enabling and disabling of the output. Thermal overload protection is designed to safeguard the MAX1735 in the event of overload fault conditions. For normal operation, do not exceed the absolute maximum junction temperature rating of +150°C. Junction temperature is greater than ambient by an amount depending on package heat dissipation and the thermal resistance from the junction to ambient (θJA): TJUNCTION = TAMBIENT + (θJA)(PDISSIPATION) where θJA for the 5-pin SOT23 is about 0.140°C/mW. _______________________________________________________________________________________ 7 MAX1735 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 MAXIMUM OUTPUT CURRENT vs. INPUT-OUTPUT VOLTAGE DIFFERENTIAL MAX SUPPLY VOLTAGE – MIN OUTPUT VOLTAGE MAXIMUM CONTINUOUS CURRENT 200 DEVICE IN DROPOUT MAXIMUM OUTPUT CURRENT (mA) 250 150 100 TA AT MAXIMUM JUNCTION TEMP (TJ = +150°C) TA =+ 5 = + 0°C = + 70°C 85 °C TA 50 0 0 1 2 3 4 5 6 INPUT-OUTPUT VOLTAGE DIFFERENTIAL (V) Figure 4. Output Current and In-Out Voltage Differential Operating Region Bounded by Available Power Dissipation at Selected Ambient Temperatures Operating Region and Power Dissipation Maximum power dissipation of the MAX1735 depends on the thermal resistance of the case and the circuit board, the temperature difference between the die junction and ambient air, and the rate of air flow (see also Thermal Overload Protection). The maximum power that can be dissipated by the device is: T − TA TJMAX − TA PMAX = JMAX = θJC + θCA θJA where the numerator expresses the temperature difference between the maximum allowed die junction (+150°C) and the surrounding air, θJC (junction to case) is the thermal resistance of the package, and θCA (case to ambient) is the thermal resistance from the package through the PC board, traces, and other material to the surrounding air. The former is a characteristic solely of the device in its package, and the latter is completely defined by PC board layout and airflow. It is important to note that the ability to dissipate power is as much a function of the PC board layout and air flow as the packaged part itself. Hence, a manufacturer can reliably provide a value for θJC, but not accurately provide a value for the total thermal resistance θJA. θJA is the sum of θJC and θCA, and the manufacturer can seldom reliably predict the thermal characteristics of the application circuit. Figure 4 shows the estimated allowable power dissipation for a MAX1735 mounted on a typical PC board at ambient temperatures of +50°C, +70°C, and +85°C. Figure 4 shows the maximum continuous output current for a particular input-to-output voltage differential, for 8 selected ambient temperatures. The working principle is that the SOT23-5 package is small enough that in a typical application circuit at room temperature, the package cannot dissipate enough power to allow -6.5V to be regulated to -1.25V at -200mA output (more than 1200mW). As ambient temperature falls, the available power dissipation increases to allow for a greater operating region. The equation for the family of curves follows: T − 70 PMAX − A θJA | IOUT | = |VOUT − VIN | where |IOUT| is in mA, |VOUT - VIN| in V, PMAX (571mW) is the absolute maximum rated power dissipation at +70°C for the SOT23-5, and θJA (0.140°C/mW) is the approximate junction-to-ambient thermal resistance of the SOT23-5 in a typical application. A key to reducing θCA, thereby increasing thermal conductivity to the PC board, is to provide large PC board pads and traces for IN. __________Applications Information Capacitor Selection and Regulator Stability Capacitors are required at the input and output of the MAX1735. Connect a 1µF or greater capacitor between IN and GND. This input capacitor serves only to lower the source impedance of the input supply in transient conditions; a smaller value can be used when the regulator is powered from a low-impedance source, such as another regulated supply or low-impedance batteries. For output voltages between -2.5V and -5.5V, connect a 1µF or greater capacitor between OUT and GND. For voltages between -1.25V and -2.5V, use a 2.2µF or greater output capacitor. The maximum value of the output capacitor to guarantee stability is 10µF. The output capacitor’s value and equivalent series resistance (ESR) affect stability and output noise. To ensure stability and optimum transient response, output capacitor ESR should be 0.1Ω or less for output voltages from -1.25V to -2.45V and 0.2Ω or less for output voltages between -2.5V and -5.5V. Inexpensive surface-mount ceramic capacitors typically have very-low ESR and are commonly available in values up to 10µF. Other low-ESR capacitors, such as surface-mount tantalum, may also be used. Do not use low-cost aluminum electrolytic capacitors due to their large size and relatively high ESR. Lastly, make sure the input and output capacitors are as close to the IC as possible to minimize the impact of PC board trace impedance. _______________________________________________________________________________________ 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 Dropout Voltage A regulator’s minimum input-to-output voltage differential dropout voltage determines the lowest usable supply voltage for an application. In battery-powered systems, this determines the useful end-of-life battery voltage. Since the MAX1735’s pass element is an N-channel MOSFET, dropout voltage is the product of R DS(ON) and the load current; see Electrical Characteristics and Dropout Voltage vs. Load Current in the Typical Operating Characteristics for details. The MAX1735 operating (ground pin) current typically remains below 125µA at full load in dropout. ___________________Chip Information TRANSISTOR COUNT: 293 _______________________________________________________________________________________ 9 MAX1735 Noise, PSRR, and Transient Response MAX1735 output noise is typically 160µVRMS. This is suitably low for most applications. See the Output Noise vs. Frequency plot in the Typical Operating Characteristics. The MAX1735 is optimized for battery-powered equipment, with low dropout voltage and low quiescent current. It maintains good transient response, AC rejection, and noise characteristics even near dropout. See Power-Supply Rejection Ratio vs. Frequency in the Typical Operating Characteristics. When operating from very noisy sources, supply noise rejection and transient response can be improved by increasing the input and output capacitance, and by employing passive postfiltering. Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) SOT-23 5L .EPS MAX1735 200mA, Negative-Output, Low-Dropout Linear Regulator in SOT23 PACKAGE OUTLINE, SOT-23, 5L 21-0057 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. 10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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