High-Voltage, Low-Power Linear Regulators for Notebook Computers

Transcription

1 ; Rev 3; 9/4 High-Voltage, Low-Power Linear Regulators General Description The are micropower, SOT23-5 linear regulators that supply always-on, keep-alive power to CMOS RAM and microcontrollers (µcs) in systems with high-voltage batteries. Key features include wide input voltage range, low dropout voltage, and low quiescent supply current. Despite a miserly 8µA (max) no-load supply current, the have excellent line-transient response and AC power-supply rejection ratio. They provide a clean, fixed 5V or 3.3V output () or an adjustable 1.24V to 28V output (MAX1616), even when subjected to fast supply-voltage changes that occur during the switchover from battery to AC adapter input power. The space-saving SOT23-5 package has excellent thermal characteristics and tolerates up to 571mW of power dissipation. Fault protection is provided by internal foldback current limiting and thermalshutdown circuitry. The are now available in lead-free packages. Applications CMOS/RTC Backup Power Microcontroller Power Notebook Computers Smart-Battery Packs PDAs and Handy-Terminals Battery-Powered Systems Typical Operating Circuit Features 4V to 28V Input Range 8µA (max) Quiescent Supply Current <1µA Shutdown Supply Current 3.3V or 5V, Pin-Selectable Output () Adjustable 1.24V to 28V Output (MAX1616) 3mA Output Current ±2% Initial Output Accuracy Thermal-Overload Protection 5-Pin SOT23 Package Low Cost Ordering Information PART EUK-T EUK+T MAX1616EUK-T MAX1616EUK+T TEMP RANGE -4 C to +85 C -4 C to +85 C -4 C to +85 C -4 C to +85 C +Denotes lead-free package. PIN- PACKAGE SOT TOP MARK ABZD ABZD ABZE ABZE Pin Configuration TOP VIEW IN PUT VOLTAGE IN 1 5 SHDN BATTERY C IN.1µF SHDN C 4.7µF GND 2 MAX1616 GND 5/ /3 (FB) SOT23-5 ( ) ARE FOR MAX1616. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at , or visit Maxim s website at

2 ABSOLUTE MAXIMUM RATINGS IN to GND...-.3V to 3V Terminal Voltages to GND SHDN to GND...-.3V to (V IN +.3V) 5/3 to GND...-.3V to (V +.3V) FB (MAX1616) to GND...-.3V to (V +.3V) to GND...-.3V to 3V Short-Circuit to GND...3sec Note 1: See Operating Region and Power Dissipation section. Continuous Current...4mA Continuous Power Dissipation (T A = +7 C) (Note 1) SOT23-5 (derate 7.1mW/ C above +7 C)...571mW Operating Temperature Range MAX161_EUK-T...-4 C to +85 C Storage Temperature Range C to +16 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 IN = 15V, SHDN = V IN, I LOAD = 5µA, T A = T MIN to T MAX, unless otherwise noted. Typical values are at T A = +25 C.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Voltage Range V IN 4 28 V Supply Current I IN SHDN = IN, T A = +25 C SHDN = IN, V IN = 6V to 28V, T A = T MIN to T MAX 15 µa Minimum Load Current 5 µa Shutdown Supply Current I IN SHDN = GND T A = +25 C 1.5 (shutdown mode) T MIN = T MIN to T MAX 3 µa Output set to 5V, Dropout Supply Current T 7 µa V IN = 4V A = +25 C I LOAD = 1mA, 5/3 = GND T A = +25 C, Output Voltage () V IN = 6V to 28V 5/3 = (Note 3) I LOAD = 5µA to 3mA, 5/3 = GND T A = T MIN to T MAX, V IN = 6V to 28V 5/3 = T A = +25 C, FB Threshold (MAX1616) FB =, I LOAD = 1mA V FBT (Note 3) V IN = 6V to 28V T A = T MIN to T MAX, I LOAD = 5µA to 3mA FB Input Current (MAX1616) I FB V FB = 1.3V na Dropout Voltage V DO I LOAD = 3mA (Note 4) 35 mv Output Current Limit V IN = 6V 1 ma Reverse Leakage Current IN = unconnected, V forced to 5V 7 µa Capacitive Load Requirements (Note 5).16 MAX Rising edge of IN or SHDN to within specification Start-Up Time Response limits, R L = 5Ω, C = 6.8µF, 1 ms V set to 5V R Start-Up Overshoot V L = 5Ω, C = 1µF within 9% of nominal OSH.5 %V output voltage V V V µf/ma 2

3 ELECTRICAL CHARACTERISTICS (continued) (V IN = 15V, SHDN = V IN, I LOAD = 5µA, T A = T MIN to T MAX, unless otherwise noted. Typical values are at T A = +25 C.) (Note 2) PARAMETER SHDN Input Threshold Voltage SYMBOL CONDITIONS MIN TYP MAX V IL.25 V IH 1.4 SHDN Input Current V SHDN = V or 15V -1 1 µa Thermal-Shutdown Temperature T SHDN UNITS V SHDN = V or 15V, hysteresis = +2 C 15 C Note 2: Limits are 1% production tested at T A = +25 C. Limits over the operating temperature range are guaranteed through correlation using standard quality-control (SQC) methods. Note 3: Pulse tested at V IN = 28V, I LOAD = 3mA to avoid exceeding package power-dissipation limits. Note 4: Guaranteed by design. Tested with V set to 5V. Dropout voltage is tested by reducing the input voltage until V drops to 1mV below its nominal value, measured with V IN starting 2V above V. Note 5: Use at least 1µF minimum for light loads. Add.125µF/mA (.2µF/mA for the MAX1616) for loads greater than 1µA, not production tested. See Capacitor Selection in the Applications Information section. V Typical Operating Characteristics (V set to 5V, T A = +25 C, unless otherwise noted.) PUT CURRENT (ma) V = 5V SAFE LOAD-CURRENT OPERATING AREA POWER- DISSIPATION LIMIT REGION -1 GROUND CURRENT (ma) GROUND CURRENT AT VARIOUS LOADS 15mA 65mA 55mA 45mA 35mA 25mA mA -2 SUPPLY CURRENT (µa) T A = +85 C SUPPLY CURRENT T A = +25 C T A = -4 C

4 Typical Operating Characteristics (continued) (V set to 5V, T A = +25 C, unless otherwise noted.) SHUTDOWN SUPPLY CURRENT (µa) SHUTDOWN SUPPLY CURRENT RIPPLE REJECTION (db) RIPPLE REJECTION vs. FREQUENCY -1 I LOAD = 1mA FREQUENCY (khz) -5 TIME TO EXIT SHUTDOWN -6 LINE-TRANSIENT RESPONSE -7 LOAD-TRANSIENT RESPONSE -8 +5V SHDN V C IN 1µF +2V V IN +1V +5V V 5mV/div V IN = 1V V C 4.7µF V 5mV/div I 3mA/div 5µs/div 5µs/div 1µs/div DROP SUPPLY CURRENT (µa) DROP SUPPLY CURRENT T A = +85 C T A = +25 C T A = C T A = -4 C -9 VIN - V (V) DROP VOLTAGE vs. LOAD CURRENT LOAD CURRENT (ma) 4

5 Pin Description 1 1 IN Positive Input Voltage. Connect to a +4V to +28V supply. 2 2 GND Ground 4 5/3 Preset Output Voltage Select. Connect to GND for 3.3V output or to for 5.V output. 5 5 SHDN Shutdown, active low input. Connect to IN for automatic start up. VREF PIN MAX1616 IN CURRENT LIMIT NAME 3 3 Regulator Output FUNCTION 4 FB Feedback Input. Regulates to 1.24V nominally. The s output voltage is fed back through an internal resistor voltage divider connected to. Set the output voltage to either 3.3V or 5.V with the 5/3 pin. Select the 5V output by connecting 5/3 to, or the 3.3V output by connecting 5/3 to GND. The MAX1616 uses external feedback, allowing the output voltage to be set by external resistors (see Setting the MAX1616 Output Voltage section). The typical FB threshold is at 1.24V. SHDN MAX1616 Shutdown The device enters shutdown mode when SHDN is low. In shutdown mode, the pass transistor, control circuit, reference, and all biases turn off, reducing the supply current to below 1µA. Connect SHDN to IN for automatic start-up. FB (MAX1616) Figure 1. Functional Diagram 5/3 () Detailed Description The low-quiescent-current linear regulators are designed primarily for high input voltage applications. The supplies a preselected 3.3V or 5.V output for loads up to 3mA. The MAX1616 provides an adjustable voltage from 1.24V to 28V. The maximum output current is a function of the package s maximum power dissipation for a given temperature. A 5µA load is required to maintain output regulation. GND Current Limit Output current is limited to 1mA (typical). The current limit exceeds the 3mA (max) safe operating limit. The output can be shorted to ground for 3 seconds without damaging the part. Thermal-Overload Protection When the junction temperature exceeds TJ = +15 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 cools by +2 C (typical), resulting in a pulsating output during continuous thermal-overload conditions. Operating Region and Power Dissipation Maximum power dissipation 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 device s power dissipa- 5

6 tion is P = I (VIN - V). The power dissipation at +7 C ambient is 571mW (see Absolute Maximum Ratings). The thermal resistance junction-to-case of the SOT23-5 package is 81 C/W, and the maximum safe junction temperature is +15 C. The GND pin performs the dual function of providing an electrical connection to ground and channeling heat away. Connect GND to ground using a large pad or ground plane. Applications Information Setting the MAX1616 Output Voltage Set the MAX1616 s output voltage with two resistors, R1 and R2 (Figure 2). Choose R2 = 25kΩ to maintain a 5µA minimum load and calculate R1 using the following equation: R1 = R2 V VFBT where V FBT = 1.24V (typical). Capacitor Selection Use a.1µf minimum capacitor on the input. Higher values will improve line-transient response. Use 1µF minimum on the output, or 4.7µF for the full 3mA load current (6.8µF, MAX1616). Otherwise, use 1µF plus.125µf/ma (.2µF/µA, MAX1616). For output voltages less than 3.3V, use 15µF instead of 6.8µF. The output capacitor s effective series resistance (ESR) must be less than 1Ω for stable operation. Output Voltage Noise The typically exhibit 5mVp-p of noise during normal operation. This is negligible in most applications. In applications that include analogto-digital converters (ADCs) of more than 12 bits, consider the ADC s power-supply-rejection specifications. Transient Response The Typical Operating Characteristics show the s load-transient response. Two of the output response s components can be observed on the load-transient graph: a DC shift from the output impedance due to the different load currents, and the transient response. Typical step changes in the load current from 1mA to 2mA produce 5mV transients. Increasing the output capacitor s value attenuates transient spikes. 6V TO 28V *15µF for V <3.3V 1 Table 1. Surface-Mount Capacitor Manufacturers TYPE Electrolytic Ceramic MANUFACTURER AVX Matsuo Sprague AVX Matsuo Chip Information TRANSISTOR COUNT: 386 CAPACITOR TPS series 267 series 593D, 595 series X7R X7R Table 2. Component Suppliers SUPPLIER PHONE AVX (83) Sprague.1µF Matsuo (714) IN MAX1616 SHDN GND Figure 2. MAX1616 Typical Application Circuit (63) FB R1 R2 PUT VOLTAGE FAX 6.8µF* (83) (714) (63)

7 Tape-and-Reel Information F E D NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD. A B D D ±.12 ± P E F K P P D P 2 A ±.12 ±.51 ±.12 ±.12 W B t K P ±.12 P ±.23 P ±.51 t.254 ±.127 W

8 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 SOT-23 5L.EPS PACKAGE LINE, SOT-23, 5L 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. 8 Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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