19-1305; Rev 1; 8/98 Switched-Capacitor Voltage Doublers ____________________________Features ♦ 5-Pin SOT23 Package ♦ +2.0V to +5.5V Input Voltage Range ♦ 98% Voltage-Conversion Efficiency ♦ 110µA Quiescent Current (MAX1682) ♦ Requires Only Two Capacitors ♦ Up to 45mA Output Current Ordering Information ________________________Applications Small LCD Panels PART Cell Phones MAX1682C/D Handy-Terminals Typical Operating Circuit IN C1+ PINPACKAGE 0°C to +70°C MAX1682EUK-T -40°C to +85°C MAX1683C/D 0°C to +70°C MAX1683EUK-T -40°C to +85°C PDAs 5 TEMP. RANGE 4 — 5 SOT23-5 Dice* 5 SOT23-5 ACLL — ACCM Note: These parts are available in tape-and-reel only. Minimum order quantity is 2500 pieces. *Dice are tested at TA = +25°C. INPUT SUPPLY VOLTAGE VIN Dice* SOT TOP MARK Pin Configuration C1 MAX1682 MAX1683 3 TOP VIEW C1GND 1 OUT 1 OUTPUT VOLTAGE 2 x VIN 2 OUT 2 5 C1+ 4 IN MAX1682 MAX1683 C2 GND C1- 3 VOLTAGE DOUBLER SOT23-5 ________________________________________________________________ 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. MAX1682/MAX1683 General Description The ultra-small MAX1682/MAX1683 monolithic, CMOS charge-pump voltage doublers accept input voltages ranging from +2.0V to +5.5V. Their high voltage-conversion efficiency (over 98%) and low operating current (110µA for MAX1682) make these devices ideal for both battery-powered and board-level voltage-doubler applications. Oscillator control circuitry and four power MOSFET switches are included on-chip. The MAX1682 operates at 12kHz and the MAX1683 operates at 35kHz. A typical application includes generating a 6V supply to power an LCD display in a hand-held PDA. Both parts are available in a 5-pin SOT23 package and can deliver 30mA with a typical voltage drop of 600mV. MAX1682/MAX1683 Switched-Capacitor Voltage Doublers ABSOLUTE MAXIMUM RATINGS IN to GND .................................................................+6V to -0.3V OUT to GND .......................................................+12V, VIN - 0.3V OUT Output Current............................................................50mA Output Short-Circuit Duration .................................1sec (Note 1) Continuous Power Dissipation (TA = +70°C) SOT23-5 (derate 7.1mW/°C above +70°C)...................571mW Operating Temperature Range MAX1682EUK/MAX1683EUK ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C Note 1: Avoid shorting OUT to GND, as it may damage the device. For temperatures above +85°C, shorting OUT to GND even instantaneously will damage the device. 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 = +5.0V, capacitor values from Table 2, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS No-Load Supply Current TA = +25°C Supply Voltage Range RLOAD = 10kΩ Minimum Operating Voltage (Note 2) MIN TYP MAX MAX1682 110 145 MAX1683 230 310 TA = +25°C 2.0 1.7 5.5 TA = 0°C to +85°C 2.1 1.8 5.5 MAX1682 8.4 12 15.6 MAX1683 24.5 35 45.5 1 Oscillator Frequency TA = +25°C Output Resistance IOUT = 5mA Voltage Conversion Efficiency IOUT = 0mA, TA = +25°C TA = +25°C 20 TA = 0°C to +85°C µA V V 50 65 98 UNITS 99.9 kHz Ω % Note 2: Once started, the MAX1682/MAX1683 typically operate down to 1V. ELECTRICAL CHARACTERISTICS (VIN = +5.0V, capacitor values from Table 2, TA = -40°C to +85°C, unless otherwise noted.) (Note 3) PARAMETER No-Load Supply Current Supply-Voltage Range Oscillator Frequency CONDITIONS MIN TYP 160 MAX1683 350 RLOAD = 10kΩ 2.3 5.5 MAX1682 6.6 18.6 MAX1683 17.5 57.8 Output Resistance IOUT = 5mA Voltage Conversion Efficiency IOUT = 0mA 65 97 Note 3: Specifications at -40°C to +85°C are guaranteed by design. 2 MAX MAX1682 _______________________________________________________________________________________ UNITS µA V kHz Ω % Switched-Capacitor Voltage Doublers 40 30 30 VIN = 3.3V 25 20 15 VIN = 5V 10 20 5 -40 -20 MAX1682 OUTPUT RESISTANCE vs. CAPACITANCE VIN = 2V 40 20 40 5 10 15 25 0 MAX1682/83 TOC05 30 25 VIN = 3.3V 20 15 600 80 C1 = C2 = 3.3µF 500 400 300 C1 = C2 = 10µF 200 VIN = 5V C1 = C2 = 33µF 100 0 0 35 0 5 10 15 20 25 30 35 0 5 10 15 20 25 30 35 40 IOUT (mA) MAX1683 OUTPUT VOLTAGE RIPPLE vs. OUTPUT CURRENT SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX1682/83 TOC07 1000 900 C1 = C2 =1µF 700 600 500 C1 = C2 = 3.3µF 300 200 60 700 CAPACITANCE (µF) 400 40 800 VIN = 2V 35 CAPACITANCE (µF) 800 20 MAX1682 OUTPUT VOLTAGE RIPPLE vs. OUTPUT CURRENT 5 30 -20 MAX1683 OUTPUT RESISTANCE vs. CAPITANCE 40 VIN = 3.3V 20 -40 80 C1 = C2 = 10µF 300 MAX1682/83 TOC09 VIN = 5V 0 VIN = 5V 10 TEMPERATURE (°C) 10 0 60 45 20 15 ILOAD = 5mA VRIPPLE (mV) 60 0 50 OUTPUT RESISTANCE (Ω) MAX1682/83 TOC4 80 VRIPPLE (mV) OUTPUT RESISTANCE (Ω) 100 20 TEMPERATURE (°C) VIN (V) 120 VIN = 3.3V 25 0 0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VIN = 2V 30 5 ILOAD = 5mA MAX1683, C1 = C2 = 10µF 10 35 MAX1682/83 TOC06 MAX1682, C1 = C2 = 10µF VIN = 2V 40 OUTPUT RESISTANCE (Ω) 50 35 MAX1682/83 TOC02 MAX1683, C1 = C2 = 3.3µF 60 40 250 SUPPLY CURRENT (µA) OUTPUT RESISTANCE (Ω) 80 OUTPUT RESISTANCE (Ω) MAX1682/83 TOC1 90 70 MAX1683 OUTPUT RESISTANCE vs. TEMPERATURE MAX1682 OUTPUT RESISTANCE vs. TEMPERATURE MAX1682/83 TOC03 OUTPUT RESISTANCE vs. SUPPLY VOLTAGE 200 MAX1683 150 100 50 100 MAX1682 0 0 0 5 10 15 20 IOUT (mA) 25 30 35 40 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 3 MAX1682/MAX1683 Typical Operating Characteristics (Typical Operating Circuit, VIN = +5V, C1 = C2 = 10µF for the MAX1682 and 3.3µF for the MAX1683, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (Typical Operating Circuit, VIN = +5V, C1 = C2 = 10µF for the MAX1682 and 3.3µF for the MAX1683, TA = +25°C, unless otherwise noted.) VIN = 3.3V 11.5 VIN = 2V 38 VIN = 5V 36 34 32 VIN = 3.3V 10 9 VIN = 5V 8 OUTPUT VOLTAGE (V) 12.0 MAX1682/83 TOC11 VIN = 5V 40 OSCILLATOR FREQUENCY (kHz) MAX1682/83 TOC10 OSCILLATOR FREQUENCY (kHz) 12.5 MAX1682 OUTPUT VOLTAGE vs. OUTPUT CURRENT MAX1683 OSCILLATOR FREQUENCY vs. TEMPERATURE VIN = 2V 7 MAX1682/83 TOC12 MAX1682 OSCILLATOR FREQUENCY vs. TEMPERATURE VIN = 3.3V 6 5 VIN = 2V 4 3 2 30 1 0 28 -20 0 20 40 60 80 -20 0 20 40 60 0 80 OUTPUT CURRENT (mA) MAX1683 OUTPUT VOLTAGE vs. OUTPUT CURRENT MAX1682 EFFICIENCY vs. LOAD CURRENT MAX1683 EFFICIENCY vs. LOAD CURRENT 98 5 VIN = 2V 94 92 VIN = 2V 90 100 98 VIN = 3.3V 88 94 92 VIN = 3.3V 88 86 86 2 84 84 1 82 82 80 80 10 15 20 25 30 35 40 45 50 VIN = 2V 90 3 0 VIN = 5V 96 EFFICIENCY (%) VIN = 3.3V VIN = 5V 96 EFFICIENCY (%) 7 6 100 MAX1682/83 TOC14 VIN = 5V 8 0 5 10 15 20 25 0 30 5 10 15 20 OUTPUT CURRENT (mA) LOAD CURRENT (mA) LOAD CURRENT (mA) MAX1682 OUTPUT RIPPLE MAX1683 OUTPUT RIPPLE START-UP VOLTAGE vs. RESISTIVE LOAD 30 MAX1682toc18 MAX1683 2.0 VSTART (V) VOUT 20mV/div VOUT 20mV/div 25 2.5 MAX1682toc17 MAX1682toc16 5 10 15 20 25 30 35 40 45 50 TEMPERATURE (°C) 9 0 5 TEMPERATURE (°C) 10 4 -40 MAX1682/83 TOC13 -40 MAX1682/83 TOC15 11.0 OUTPUT VOLTAGE (V) MAX1682/MAX1683 Switched-Capacitor Voltage Doublers 1.5 1.0 MAX1682 0.5 0 20µs/div ILOAD = 5mA, VIN = 5V, C1 = C2 = 10µF 4 20µs/div ILOAD = 5mA, VIN = 5V, C1 = 3.3µF, C2 = 10µF 700 300 100 70 30 10 7 RLOAD (kΩ) _______________________________________________________________________________________ 3 1 0.7 0.3 Switched-Capacitor Voltage Doublers PIN NAME FUNCTION 1 GND Ground 2 OUT Doubled Output Voltage. Connect C2 between OUT and GND. 3 C1- Negative Terminal of the Flying Capacitor 4 IN 5 C1+ Efficiency Considerations The power efficiency of a switched-capacitor voltage converter is affected by three factors: the internal losses in the converter IC, the resistive losses of the capacitors, and the conversion losses during charge transfer between the capacitors. The total power loss is: ΣPLOSS = PINTERNAL LOSSES + PPUMP CAPACITOR LOSSES + PCONVERSION LOSSES Input Supply Positive Terminal of the Flying Capacitor _______________Detailed Description The MAX1682/MAX1683 capacitive charge pumps double the voltage applied to their input. Figure 1 shows a simplified functional diagram of an ideal voltage doubler. During the first half-cycle, switches S1 and S2 close, and capacitor C1 charges to VIN. During the second half cycle, S1 and S2 open, S3 and S4 close, and C1 is level shifted upward by VIN volts. This connects C1 to the reservoir capacitor C2, allowing energy to be delivered to the output as necessary. The actual voltage is slightly lower than 2 x VIN , since switches S1–S4 have resistance and the load drains charge from C2. Charge-Pump Output The MAX1682/MAX1683 have a finite output resistance of about 20Ω (Table 2). As the load current increases, the devices’ output voltage (VOUT) droops. The droop equals the current drawn from VOUT times the circuit’s output impedance (RS), as follows: VDROOP = IOUT x RS VOUT = 2 x VIN - VDROOP The internal losses are associated with the IC’s internal functions, such as driving the switches, oscillator, etc. These losses are affected by operating conditions such as input voltage, temperature, and frequency. The next two losses are associated with the voltage converter circuit’s output resistance. Switch losses occur because of the on-resistance of the MOSFET switches in the IC. Charge-pump capacitor losses occur because of their ESR. The relationship between these losses and the output resistance is as follows: PPUMP CAPACITOR LOSSES + PSWITCH LOSSES = IOUT 2 x ROUT 1 + 2RSWITCHES + 4ESRC1 fOSC x C1 ROUT ≅ ( ) + ESRC2 where fOSC is the oscillator frequency. The first term is the effective resistance from an ideal switchedcapacitor circuit (Figures 2a and 2b). f V+ VOUT C2 RL C1 S1 S3 VIN Figure 2a. Switched-Capacitor Model C1 VOUT C2 S2 S4 REQUIV V+ VOUT 1 REQUIV = f × C1 C2 RL VIN Figure 1. Simplified Functional Diagram of Ideal Voltage Doubler Figure 2b. Equivalent Circuit _______________________________________________________________________________________ 5 MAX1682/MAX1683 _____________________Pin Description MAX1682/MAX1683 Switched-Capacitor Voltage Doublers Conversion losses occur during the charge transfer between C1 and C2 when there is a voltage difference between them. The power loss is: 2 2 PCONVERSION LOSS = 1/ 2C1 4VIN − VOUT + 2 1/ 2C2 2VOUT VRIPPLE − V RIPPLE x fOSC where VRIPPLE is the peak-to-peak output voltage ripple determined by the output capacitor and load current (see Output Capacitor section). Choose capacitor values that decrease the output resistance (see Flying Capacitor section). Applications Information Flying Capacitor (C1) To maintain the lowest output resistance, use capacitors with low ESR. Suitable capacitor manufacturers are listed in Table 1. The charge-pump output resistance is a function of C1 and C2’s ESR and the internal switch resistance, as shown in the equation for R OUT in the Efficiency Considerations section. Minimizing the charge-pump capacitor’s ESR minimizes the total resistance. Suggested values are listed in Tables 2 and 3. Using a larger flying capacitor reduces the output impedance and improves efficiency (see the Efficiency Considerations section). Above a certain point, increasing C1’s capacitance has a negligible effect because the output resistance becomes dominated by the internal switch resistance and capacitor ESR (see the Output Resistance vs. Capacitance graph in the Typical Operating Characteristics ). Table 2 lists the most desirable capacitor values—those that produce a low output resistance. But when space is a constraint, it may be necessary to sacrifice low output resistance for the sake of small capacitor size. Table 3 demonstrates how the capacitor affects output resistance. Output Capacitor (C2) Increasing the output capacitance reduces the output ripple voltage. Decreasing its ESR reduces both output resistance and ripple. Smaller capacitance values can be used with light loads. Use the following equation to calculate the peak-to-peak ripple: VRIPPLE = IOUT / (fOSC x C2) + 2 x IOUT x ESRC2 Input Bypass Capacitor Bypass the incoming supply to reduce its AC impedance and the impact of the MAX1682/MAX1683’s switching noise. When loaded, the circuit draws a continuous current of 2 x IOUT. A 0.1µF bypass capacitor is sufficient. Table 1. Recommended Capacitor Manufacturers PRODUCTION METHOD MANUFACTURER SERIES PHONE FAX AVX TPS 803-946-0690 803-448-2170 Surface-Mount Tantalum Surface-Mount Ceramic Matsuo 267 714-969-2491 714-960-6492 Sprague 593D, 595D 603-224-1961 603-224-1430 AVX X7R 803-946-0590 803-626-3123 Matsuo X7R 714-969-2491 714-960-6492 Table 2. Suggested Capacitor Values for Low Output Resistance 6 PART FREQUENCY (kHz) MAX1682 MAX1683 Table 3. Suggested Capacitor Values for Minimum Size CAPACITOR VALUE (µF) TYPICAL ROUT (Ω) PART FREQUENCY (kHz) CAPACITOR VALUE (µF) TYPICAL ROUT (Ω) 12 10 20 MAX1682 12 3.3 35 35 3.3 20 MAX1683 35 1 35 _______________________________________________________________________________________ Switched-Capacitor Voltage Doublers Paralleling Devices Paralleling multiple MAX1682 or MAX1683s reduces the output resistance. Each device requires its own pump capacitor (C1), but the reservoir capacitor (C2) serves all devices (Figure 4). Increase C2’s value by a factor of n, where n is the number of parallel devices. Figure 4 shows the equation for calculating output resistance. Layout and Grounding Good layout is important, primarily for good noise performance. To ensure good layout, mount all components as close together as possible, keep traces short to minimize parasitic inductance and capacitance, and use a ground plane. INPUT SUPPLY VOLTAGE INPUT SUPPLY VOLTAGE C1+ IN C1 IN C1+ MAX1682 MAX1683 C1+ MAX1682 GND C1 OUTPUT VOLTAGE C1 GND C1 GND OUT MAX1682 MAX1683 OUTPUT VOLTAGE OUT C1- C1- IN C1+ MAX1682 MAX1683 GND MAX1683 C1- IN C2 C1- OUT OUT C2 ROUT = ROUT OF SINGLE DEVICE NUMBER OF DEVICES Figure 3. Cascading Devices C2 Figure 4. Paralleling Devices _______________________________________________________________________________________ 7 MAX1682/MAX1683 Cascading Devices Devices can be cascaded to produce an even larger voltage (Figure 3). The unloaded output voltage is nominally (n + 1) x VIN, where n is the number of voltage doublers used. This voltage is reduced by the output resistance of the first device multiplied by the quiescent current of the second. The output resistance increases when devices are cascaded. Using a two-stage doubler as an example, output resistance can be approximated as ROUT = 2 x ROUT1 + ROUT2 , where ROUT1 is the output resistance of the first stage and ROUT2 is the output resistance of the second stage. A typical value for a two-stage voltage doubler is 60Ω (with C1 at 10µF for MAX1682 and 3.3µF for MAX1683). For n stages with the same C1 value, ROUT = (2n - 1) x ROUT1. ___________________Chip Information TRANSISTOR COUNT: 97 SUBSTRATE CONNECTED TO OUT ________________________________________________________Package Information SOT5L.EPS MAX1682/MAX1683 Switched-Capacitor Voltage Doublers 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.