MAX1595_09

19-2107; Rev 2; 6/09 Regulated 3.3V/5.0V Step-Up/Step-Down Charge Pump General Description The MAX1595 charge-pump regulator generates either 3.3V or 5V from a 1.8V to 5.5V input. The unique control architecture allows the regulator to step up or step down the input voltage to maintain output regulation. The 1MHz switching frequency, combined with a unique control scheme, allows the use of a ceramic capacitor as small as 1µF for 125mA of output current. The complete regulator requires three external capacitors—no inductor is needed. The MAX1595 is specifically designed to serve as a high-power, highefficiency auxiliary supply in applications that demand a compact design. The MAX1595 is offered in spacesaving 8-pin µMAX and high-power 12-pin thin QFN packages. Features ♦ Ultra-Small: Requires Only Three Ceramic Capacitors ♦ No Inductors Required ♦ Up to 125mA Output Current ♦ Regulated ±3% Output Voltage ♦ 1MHz Switching Frequency ♦ 1.8V to 5.5V Input Voltage ♦ 220µA Quiescent Current ♦ 0.1µA Shutdown Current ♦ Load Disconnect in Shutdown MAX1595 Applications White LED Power Flash Memory Supplies Battery-Powered Applications Miniature Equipment PCMCIA Cards 3.3V to 5V Local Conversion Applications Backup-Battery Boost Converters 3V to 5V GSM SIMM Cards Ordering Information PART MAX1595EUA33+ MAX1595ETC33+ MAX1595EUA50+ MAX1595ETC50+ TEMP RANGE -40°C to +85°C -40°C to +85°C -40°C to +85°C PIN-PACKAGE 8 µMAX 12 Thin QFN-EP* 8 µMAX 12 Thin QFN-EP* -40°C to +85°C +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Selector Guide PART MAX1595EUA33+ MAX1595ETC33+ VOUT (V)** 3.3 3.3 TOP MARK UDAA AAEH Typical Operating Circuit UJAN 5.0 MAX1595ETC50+ AAEI 5.0 **Contact factory for other fixed-output voltages from 2.7V to 5.0V. MAX1595EUA50+ Pin Configurations CXN CXP INPUT MAX1595 IN OUT AOUT SHDN PGND GND OUTPUT TOP VIEW AOUT SHDN IN GND 1 2 3 4 8 OUT CXP CXN PGND MAX1595 7 6 5 μMAX Pin Configurations continued at end of data sheet. Maxim Integrated Products 1 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. Regulated 3.3V/5.0V Step-Up/Step-Down Charge Pump MAX1595 ABSOLUTE MAXIMUM RATINGS IN, OUT, AOUT to GND............................................-0.3V to +6V SHDN to PGND ........................................................-0.3V to +6V PGND to GND .......................................................-0.3V to +0.3V CXN to PGND.....................-0.3V to (Lower of IN + 0.8V or 6.3V) CXP to GND ................................-0.8V to (Higher of OUT + 0.8V or IN + 0.8V but not greater than 6V) Continuous Output Current ...............................................150mA Continuous Power Dissipation (TA = +70°C) 8-Pin µMAX (derate 4.5mW/°C above +70°C) ............362mW 12-Pin Thin QFN (derate 18.5mW/°C above +70°C)............................................................1481mW 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 = 2V for MAX1595_ _ _33, VIN = 3V for MAX1595_ _ _50, CIN = 1µF, CX = 0.22µF, COUT = 1µF, TA = -40° to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Input Voltage Range Input Undervoltage Lockout Threshold Input Undervoltage Lockout Hysteresis 0 < ILOAD < 125mA, VIN = +3.0V Output Voltage VOUT TA = 0°C to +85°C TA = -40°C to +85°C 4.85 4.80 3.20 3.16 3.20 3.16 220 240 0.85 1.0 3.33 3.33 SYMBOL VIN CONDITIONS MIN 1.8 1.40 1.60 40 5.05 5.15 5.20 3.40 3.44 3.40 3.44 320 350 1.15 5 0.6 1.6 0.1 µA MHz µA V V µA V TYP MAX 5.5 1.72 UNITS V V mV 0 < ILOAD < 75mA, VIN TA = 0°C to +85°C = +2.0V TA = -40°C to +85°C 0 < ILOAD < 30mA, VIN TA = 0°C to +85°C = +1.8V TA = -40°C to +85°C No-Load Input Current Switching Frequency Shutdown Supply Current SHDN Input Voltage Low SHDN Input Voltage High SHDN Input Leakage Current IQ fOSC ISHDN VINL VINH VIN = +2.0V, MAX1595_ _ _33 VIN = +3.0V, MAX1595_ _ _50 ILOAD > 20mA, VOUT > VIN VSHDN = 0V, VIN = +5.5V, VOUT = 0V VIN = 2.0V to 5.5V VIN = 2.0V to 5.5V Note 1: Specifications to -40°C are guaranteed by design, not production tested. 2 _______________________________________________________________________________________ Regulated 3.3V/5.0V Step-Up/Step-Down Charge Pump __________________________________________Typical Operating Characteristics (Circuit of Figure 4, VIN = 2V for MAX1595_ _ _33, VIN = 3V for MAX1595_ _ _50, TA = +25°C, unless otherwise noted.) NO LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX1595 toc01 MAX1595 OUTPUT WAVEFORM MAX1595 toc02 OUTPUT VOLTAGE vs. LOAD CURRENT 5.04 OUTPUT VOLTAGE (V) 5.02 5.00 4.98 4.96 4.94 4.92 VIN = 3V VIN = 3.3V VIN = 3.6V MAX1595 toc03 10000 5.06 1000 SUPPLY CURRENT (μA) 10 1 VOUT = 5V 0 1 2 3 4 5 6 VOUT = 5V 50mV/div 100 0.1 SUPPLY VOLTAGE (V) 4.90 200ns/div OUTPUT WAVEFORM. AC-COUPLED. VIN = 3.6V, ILOAD = 100mA, COUT = 1μF 1 10 100 LOAD CURRENT (mA) VOUT = 5V 1000 3V EFFICIENCY vs. LOAD CURRENT 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 1 10 LOAD CURRENT (mA) 100 VIN = 2.4V VIN = 1.8V MAX1595 toc04 5V EFFICIENCY vs. LOAD CURRENT 90 80 EFFICEINCY (%) MAX1595 toc05 SHUTDOWN TIMING MAX1595 toc06 100 100 VIN = 3V 5V A 70 60 50 40 30 20 10 0 0.1 1 10 100 1000 LOAD CURRENT (mA) 100μs/div A: OUTPUT VOLTAGE: RL = 100Ω, 2V/div B: SHDN VOLTAGE: 2V/div VIN = 3.6V B VIN = 3.3V LINE-TRANSIENT RESPONSE MAX1595 toc07 LOAD-TRANSIENT RESPONSE MAX1595 toc08 OUTPUT VOLTAGE vs. SUPPLY VOLTAGE VOUT = 5V, ILOAD = 125mA MAX1595 toc09 6 A A OUTPUT VOLTAGE (V) 4 3 2 1 COUT = 1μF 2ms/div A: INPUT VOLTAGE: VIN = 3.1V TO 3.6V, 500mV/div B: OUTPUT VOLTAGE: ILOAD = 50mA, 100mV/div 200μs/div A: LOAD CURRENT: ILOAD = 5mA to 95mA, 100mA/div B: OUTPUT VOLTAGE: AC-COUPLED 100mV/div 0 0 1 2 3 4 5 6 SUPPLY VOLTAGE (V) VOUT = 3.3V, ILOAD = 75mA 5 B B _______________________________________________________________________________________ 3 Regulated 3.3V/5.0V Step-Up/Step-Down Charge Pump MAX1595 Pin Description PIN MAX1595 µMAX 1 2 3 4 5 6 7 8 — MAX1595 THIN QFN-EP 12 1 2, 3 4 5, 6 7, 8 9 10, 11 — NAME FUNCTION Analog Power and Sense Input for Error Amplifier/Comparator. Connect to OUT at output filter capacitor. Shutdown Input. When SHDN = low, the device turns off; when SHDN = high, the device activates. In shutdown, OUT is disconnected from IN. Input Supply. Can range from 1.8V to 5.5V. Bypass to GND with a 1µF capacitor. Ground Power Ground Negative Terminal of the Charge-Pump Transfer Capacitor Positive Terminal of the Charge-Pump Transfer Capacitor Output. Bypass to GND with output capacitor filter. Exposed Pad. Internally connected to GND. Connect to a large ground plane to maximize thermal performance. Not intended as an electrical connection point (thin QFN package only). AOUT SHDN IN GND PGND CXN CXP OUT EP Detailed Description The MAX1595 charge pump provides either a 3.3V or 5V regulated output. It delivers a maximum 125mA load current. In addition, to boost regulating from a lower supply, it is also capable of buck regulating from supplies that exceed the regulated output by a diode drop or more. Designed specifically for compact applications, a complete regulator circuit requires only three small external capacitors. An innovative control scheme provides constant frequency operation from medium to heavy loads, while smoothly transitioning to low-power mode at light loads to maintain optimum efficiency. In buck mode, switch S1 (in Figure 1) is switched continuously to IN, while switch S2 alternates between IN and OUT. An amount of charge proportional to the difference between the output voltage and the supply voltage is stored on CX, which gets transferred to the output when the regulation point is reached. Maximum output ripple is proportional to the difference between the supply voltage and the output voltage, as well as to the ratio of the transfer capacitor (CX) to the output capacitor (COUT). The MAX1595 consists of an error amplifier, a 1.23V bandgap reference, internal resistive feedback network, oscillator, high-current MOSFET switches, and shutdown and control logic. Figure 1 shows an idealized unregulated charge-pump voltage doubler. The oscillator runs at a 50% duty cycle. During one half of the period, the transfer capacitor (CX) charges to the input voltage. During the other half, the doubler transfers the sum of CX and input voltage to the output filter capacitor (COUT). Rather 4 IN S1 CX S2 OUT CIN COUT OSC Figure 1. Unregulated Voltage Doubler than doubling the input voltage, the MAX1595 provides a regulated output voltage of either 3.3V or 5.0V. Shutdown Driving SHDN low places the device in shutdown mode. The device draws 0.1µA of supply current in this mode. When driven high, the MAX1595 enters a soft-start mode. Soft-start mode terminates when the output voltage regulates, or after 2ms, whichever comes first. In shutdown, the output disconnects from the input. Undervoltage Lockout The MAX1595 has an undervoltage-lockout that deactivates the devices when the input voltage falls below 1.6V. Below UVLO, hysteresis holds the device in shutdown until the input voltage rises 40mV above the lockout threshold. _______________________________________________________________________________________ Regulated 3.3V/5.0V Step-Up/Step-Down Charge Pump MAX1595 Applications Information Using white LEDs to backlight LCDs is an increasingly popular approach for portable information devices (Figure 2). Because the forward voltage of white LEDs exceeds the available battery voltage, the use of a charge pump such as the MAX1595 provides high efficiency, small size, and constant light output with changing battery voltages. If the output is used only to light LEDs, the output capacitor can be greatly reduced. The frequency modulation of the LED intensity is not discernible to the human eye, and the smaller capacitor saves both size and cost. Adding two Schottky diodes and two capacitors implements a tripler and allows the MAX1595_ _ _50 to regulate a current of 75mA with a supply voltage as low as 2.3V (Figure 3). CX = 0.1μF CXP CXN MAX1595_ _ _50 VIN IN OUT AOUT CIN = 1μF SHDN PGND GND COUT = 0.47μF 100Ω 100Ω 100Ω Figure 2. White LED Bias Supply Capacitor Selection The MAX1595 requires only three external capacitors (Figure 4). Their values are closely linked to the output current capacity, oscillator frequency, output noise content, and mode of operation. Generally, the transfer capacitor (CX) will be the smallest, and the input capacitor (CIN) is twice as large as CX. Higher switching frequencies allow the use of the smaller CX and CIN. The output capacitor (COUT) can be anywhere from 5-times to 50-times larger than CX. Table 1 shows recommended capacitor values. In addition, the following equation approximates output ripple: VRIPPLE ≅ IOUT / (2 x fOSC x COUT) Table 2 lists the manufacturers of recommended capacitors. Ceramic capacitors will provide the lowest ripple due to their typically lower ESR. Figure 3. Regulated Voltage Tripler INPUT 2.3V 1μF IN SHDN AOUT OUT 1μF 0.22μF OUTPUT REGULATED 5V 1μF 75mA MAX1595_ _ _50 CXP 0.22μF PGND GND CXN Power Dissipation The power dissipated in the MAX1595 depends on output current and is accurately described by: PDISS = IOUT (2VIN - VOUT) ON CXP 2 3 OFF IN CIN 1μF SHDN CXN IN PGND 5 7 6 8 1 COUT 1μF CX 0.22μF OUT PDISS must be less than that allowed by the package rating. MAX1595 OUT GND 4 AOUT Layout Considerations All capacitors should be soldered in close proximity to the IC. Connect ground and power ground through a short, low-impedance trace. The input supply trace should be as short as possible. Otherwise, an additional input supply filter capacitor (tantalum or electrolytic) may be required. Figure 4. Standard Operating Circuit 5 _______________________________________________________________________________________ Regulated 3.3V/5.0V Step-Up/Step-Down Charge Pump MAX1595 Table 1. Recommended Capacitor Values OUTPUT RIPPLE (mV) 70 35 CIN (µF) 1 2.2 CX (µF) 0.22 0.47 COUT (µF) 1 2.2 Table 2. Recommended Capacitor Manufacturers VALUE (µF) 1 0.22 0.47 0.1 VOLTAGE (V) 10 10 10 10 TYPE X7R X7R X7R X7R SIZE 0805 0603 0603 0603 MANUFACTURER Taiyo Yuden Taiyo Yuden Taiyo Yuden Taiyo Yuden PART LMK212BJ105MG LMK107BJ224MA LMK107BJ474MA LMK107BJ104MA Pin Configurations (continued) TOP VIEW AOUT 12 SHDN IN IN 1 2 3 OUT 11 OUT 10 9 8 7 CXP CXN CXN Chip Information PROCESS: CMOS Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 8 µMAX 12 Thin QFN PACKAGE CODE U8+1 1244+4 DOCUMENT NO. 21-0036 21-0139 MAX1595 4 GND 5 PGND 6 PGND THIN QFN 4mm × 4mm 6 _______________________________________________________________________________________ Regulated 3.3V/5.0V Step-Up/Down Charge Pump Revision History REVISION NUMBER 2 REVISION DATE 6/09 DESCRIPTION Added EP (exposed pad) and top mark information PAGES CHANGED 1, 2, 4, 6 MAX1595 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 _____________________ 7 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.