19-1792; Rev 0; 9/00 SC70 Inverting Charge Pumps with Shutdown Features ♦ 30mA Output Current ♦ Low 15Ω Output Resistance ♦ 68µA Supply Current (MAX1852) ♦ Requires Only Two 0.68µF Capacitors (MAX1853) ♦ +2.5V to +5.5V Input Voltage Range ♦ 0.1µA Logic-Controlled Shutdown ♦ Two Switching Frequencies 50kHz (MAX1852) 200kHz (MAX1853) ♦ Slew-Rate Limited to Reduce EMI ♦ Ultra-Small 6-Pin SC70 Package Applications Negative Supply from +5V or +3.3V Logic Supplies Small LCD Panels Ordering Information GaAsFET Bias Supplies MAX1852EXT TEMP. RANGE -40°C to +85°C PINPACKAGE 6 SC70 MAX1853EXT -40°C to +85°C 6 SC70 PART Handy-Terminals, PDAs Battery-Operated Equipment TOP MARK AAL AAM Pin Configuration Typical Operating Circuit 0.68µF TOP VIEW INPUT 2.5V TO 5.5V C1+ C1OUT IN MAX1853 SHDN ON OFF NEGATIVE OUTPUT -1 ✕ VIN 30mA OUT 1 GND 2 SHDN 3 6 MAX1852 MAX1853 C1+ 5 C1- 0.68µF 4 IN GND SC70-6 ________________________________________________________________ Maxim Integrated Products 1 For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX1852/MAX1853 General Description The MAX1852/MAX1853 monolithic, CMOS chargepump voltage inverters in the ultra-small SC70 package feature a low 15Ω output resistance, permitting loads up to 30mA with maximum efficiency. The MAX1852/ MAX1853 are available with operating frequencies of 50kHz and 200kHz, respectively, allowing optimization of supply current or external component size. Small external components and micropower shutdown mode make these devices ideal for both battery-powered and board-level voltage conversion applications. Oscillator control circuitry and four power-MOSFET switches are included on-chip. Applications include generating a negative supply from a +5V or +3.3V logic supply to power analog circuitry. Both versions come in a 6-pin SC70 package that is 40% smaller than a SOT23. MAX1852/MAX1853 SC70 Inverting Charge Pumps with Shutdown ABSOLUTE MAXIMUM RATINGS IN to GND .................................................................-0.3V to +6V C1+, SHDN to GND .....................................-0.3V to (VIN + 0.3V) C1- to GND...............................................(VOUT - 0.3V) to +0.3V OUT to GND .............................................................+0.3V to -6V OUT Short-Circuit to GND ..............................................1 minute Continuous Power Dissipation (TA = +70°C) 6-Pin SC70 (derate 3.1mW/°C above +70°C) .............245mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°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 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS Supply Voltage Range Quiescent Supply Current MAX1853 SHDN = GND MAX1852 Oscillator Frequency MAX1853 Voltage Conversion Efficiency Output Resistance (Note 2) TYP 2.5 MAX1852 Shutdown Supply Current MIN TA = +25°C Output Current Continuous, long-term SHDN Input Logic High +2.5V ≤ VIN ≤ +5.5V SHDN Input Logic Low +2.5V ≤ VIN ≤ +5.5V SHDN Bias Current SHDN = GND or IN Wake-Up Time From Shutdown IOUT = 5mA 165 TA = -40°C to +85°C TA = +25°C 0.002 0.01 32 V 130 320 TA = -40°C to +85°C 25 TA = +25°C 130 TA = -40°C to +85°C 110 99 TA = +25°C 0.5 50 68 200 270 78 99.9 15 TA = -40°C to +85°C 40 30 TA = +85°C kHz Ω mARMS V 0.3 × VIN -100 µA % 30 0.7 × VIN TA = +25°C µA 310 1 10 MAX1852 260 MAX1853 112 Note 1: All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design. Note 2: Output resistance is guaranteed with capacitor ESR of 0.3Ω or less. 2 5.5 350 TA = +85°C TA = +25°C UNITS 150 TA = +25°C IOUT = 0 IOUT = 10mA 75 TA = -40°C to +85°C MAX _______________________________________________________________________________________ 100 V nA µs SC70 Inverting Charge Pumps with Shutdown MAX1853 OUTPUT VOLTAGE vs. LOAD CURRENT VIN = +3.3V -3.5 -4.0 VIN = +5V -3.0 90 -3.5 -4.0 VIN = +3.3V 70 VIN = +2.5V 60 50 40 30 VIN = +5V -4.5 VIN = +5V 80 EFFICIENCY (%) -3.0 -2.5 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) VIN = +3.3V 100 MAX1852/3 toc02 -2.5 -4.5 -2.0 MAX1852/3 toc01 -2.0 MAX1852 EFFICIENCY vs. LOAD CURRENT MAX1852/3 toc03 MAX1852 OUTPUT VOLTAGE vs. LOAD CURRENT 20 -5.0 -5.5 -5.5 5 10 15 20 25 5 10 15 20 25 MAX1853 EFFICIENCY vs. LOAD CURRENT OUTPUT RESISTANCE vs. INPUT VOLTAGE VIN = +2.5V 60 50 40 30 23 22 21 20 19 18 MAX1853 17 MAX1852 16 120 80 60 20 0 13 25 3.0 3.5 4.0 4.5 5.0 0 5.5 1 2 3 4 5 LOAD CURRENT (mA) INPUT VOLTAGE (V) SUPPLY VOLTAGE (V) SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE MAX1852 OUTPUT RESISTANCE vs. TEMPERATURE MAX1853 OUTPUT RESISTANCE vs. TEMPERATURE 5 4 3 2 24 VIN = +2.5V 22 VIN = +3.3V 20 18 VIN = +5V 16 -15 10 35 TEMPERATURE (°C) 60 85 VIN = +2.5V 24 22 VIN = +3.3V 20 18 VIN = +5V 16 12 12 0 26 14 14 1 MAX1852/3 toc09 26 28 OUTPUT RESISTANCE (Ω) 6 MAX1852/3 toc08 7 28 OUTPUT RESISTANCE (Ω) MAX1852/3 toc07 8 -40 MAX1852 0 2.5 30 MAX1853 100 14 20 30 140 10 15 25 160 40 10 20 180 15 5 15 200 20 0 10 NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT (µA) VIN = +3.3V 70 5 LOAD CURRENT (mA) MAX1852/3 toc05 MAX1852/3 toc04 VIN = +5V 80 0 30 LOAD CURRENT (mA) 90 SUPPLY CURRENT (nA) 0 0 LOAD CURRENT (mA) 100 EFFICIENCY (%) 30 OUTPUT RESISTANCE (Ω) 0 10 MAX1852/3 toc06 -5.0 -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) _______________________________________________________________________________________ 3 MAX1852/MAX1853 Typical Operating Characteristics (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (Circuit of Figure 1, capacitors from Table 2, VIN = +5V, SHDN = IN, TA = +25°C, unless otherwise noted.) MAX1852 CHARGE-PUMP FREQUENCY vs. TEMPERATURE MAX1853 CHARGE-PUMP FREQUENCY vs. TEMPERATURE 56 55 54 220 215 210 53 52 MAX1852/3 toc12 270 FREQUENCY (kHz) 57 225 FREQUENCY (kHz) FREQUENCY (kHz) 58 MAX1852/3 toc11 59 CHARGE-PUMP FREQUENCY vs. INPUT VOLTAGE 230 MAX1852/3 toc10 60 MAX1853 220 170 120 70 205 MAX1852 51 20 200 -40 -20 0 20 60 40 80 -40 -20 0 20 40 60 2.0 80 2.5 3.0 3.5 4.0 5.0 MAX1852 AND MAX1853 OUTPUT VOLTAGE vs. INPUT VOLTAGE OUTPUT VOLTAGE RIPPLE vs. CAPACITANCE MAX1852 OUTPUT NOISE AND RIPPLE -2.5 -3.0 -3.5 -4.0 -4.5 -5.0 350 OUTPUT VOLTAGE RIPPLE (mV) ILOAD = 10mA C1 = C2 ILOAD = 10mA 300 MAX1852/3 toc14 INPUT VOLTAGE (V) MAX1852/3 toc13 TEMPERATURE (°C) -2.0 5.5 C1 = C2 = 4.7µF 250 200 150 VOUT 20mV/div MAX1852 100 MAX1853 50 -5.5 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 10µs/div ILOAD = 10mA, AC-COUPLED 0.2 0.7 1.2 1.7 2.2 2.7 3.2 3.7 4.2 4.7 INPUT VOLTAGE (V) CAPACITANCE (µF) MAX1853 OUTPUT NOISE AND RIPPLE MAX1853 STARTUP FROM SHUTDOWN MAX1852 STARTUP FROM SHUTDOWN MAX1852/3 toc18 MAX1852/3 toc16 MAX1852/3 toc17 C1 = C2 = 1µF SHDN SHDN 0 VOUT 20mV/div 2V/div 0 2V/div 0 0 VOUT VOUT 2µs/div ILOAD = 10mA, AC-COUPLED 4 4.5 TEMPERATURE (°C) MAX1852/3 toc15 50 OUTPUT VOLTAGE (V) MAX1852/MAX1853 SC70 Inverting Charge Pumps with Shutdown 100µs/div 40µs/div _______________________________________________________________________________________ SC70 Inverting Charge Pumps with Shutdown C1 PIN NAME 1 OUT 2 3 FUNCTION Inverting Charge-Pump Output GND Ground SHDN Shutdown Input. Drive this pin high for normal operation; drive it low for shutdown mode. 4 IN Power-Supply Voltage Input. Input range is +2.5V to +5.5V. 5 C1- Negative Terminal of the Flying Capacitor C1+ Positive Terminal of the Flying Capacitor 6 Detailed Description The MAX1852/MAX1853 charge pumps invert the voltage applied to their input. For highest performance use low equivalent series resistance (ESR) capacitors (e.g., ceramic). During the first half-cycle, switches S2 and S4 open, switches S1 and S3 close, and capacitor C1 charges to the voltage at IN (Figure 2). During the second halfcycle, S1 and S3 open, S2 and S4 close, and C1 is level shifted downward by VIN volts. This connects C1 in parallel with the reservoir capacitor C2. If the voltage across C2 is smaller than the voltage across C1, charge flows from C1 to C2 until the voltage across C2 reaches -VIN. The actual voltage at the output is more positive than -VIN since switches S1–S4 have resistance and the load drains charge from C2. Efficiency Considerations The efficiency of the MAX1852/MAX1853 is dominated by their quiescent supply current (IQ) at low output current and by their output impedance (ROUT) at higher output current; it is given by: IOUT IOUT x ROUT η≅ 1 − VIN IOUT + IQ where the output impedance is roughly approximated by: 1 ROUT ≅ + 2RSW + 4ESRC1 + ESRC2 fOSC x C1 ( ) The first term is the effective resistance of an ideal switched-capacitor circuit (Figures 3a and 3b), and RSW is the sum of the charge pump’s internal switch INPUT 2.5V TO 5.5V 4 6 C1+ 5 C1- IN OUT C3 ON OFF 3 RL MAX1852 MAX1853 SHDN NEGATIVE OUTPUT -1 ✕ VIN 1 C2 GND 2 TE: ( Figure 1. Typical Application Circuit resistances (typically 6Ω at VIN = +5V). The typical output impedance is more accurately determined from the Typical Operating Characteristics. Shutdown The MAX1852/MAX1853 have a logic-controlled shutdown input. Driving SHDN low places the devices in a low-power shutdown mode. The charge-pump switching halts, supply current is reduced to 2nA. Driving SHDN high will restart the charge pump. The switching frequency and capacitor values determine how soon the device will reach 90% of the input voltage. Applications Information Capacitor Selection The charge-pump output resistance is a function of the ESR of C1 and C2. To maintain the lowest output resistance, use capacitors with low ESR. (See Table 1 for a list of recommended manufacturers.) Tables 2 and 3 suggest capacitor values for minimizing output resistance or capacitor size. Flying Capacitor (C1) Increasing the flying capacitor’s value reduces the output resistance. Above a certain point, increasing C1’s capacitance has negligible effect because the output resistance is then dominated by internal switch resistance and capacitor ESR. Output Capacitor (C2) Increasing the output capacitor’s value reduces the output ripple voltage. Decreasing its ESR reduces both output resistance and ripple. Lower capacitance values can be used with light loads if higher output ripple can be tolerated. Use the following equation to calculate the peak-to-peak ripple: _______________________________________________________________________________________ 5 MAX1852/MAX1853 Pin Description MAX1852/MAX1853 SC70 Inverting Charge Pumps with Shutdown S1 REQUIV S2 IN V+ C1 S3 VOUT REQUIV = 1 fOSC ✕ C1 C2 RL C2 S4 VOUT = -(VIN) Figure 3b. Equivalent Circuit Paralleling Devices Figure 2. Ideal Voltage Inverter fOSC V+ VOUT C1 C2 RL Figure 3a. Switched-Capacitor Model VRIPPLE = IOUT + 2 × IOUT × ESRC2 2(fOSC )C2 Input Bypass Capacitor (C3) If necessary, bypass the incoming supply to reduce its AC impedance and the impact of the MAX1852/ MAX1853s’ switching noise. A bypass capacitor with a value equal to that of C1 is recommended. Voltage Inverter The most common application for these devices is a charge-pump voltage inverter (Figure 1). This application requires only two external components—capacitors C1 and C2—plus a bypass capacitor, if necessary. Refer to the Capacitor Selection section for suggested capacitor types. Paralleling multiple MAX1852/MAX1853s reduces the output resistance. Each device requires its own pump capacitor (C1), but the reservoir capacitor (C2) serves all devices (Figure 5). Increase C2’s value by a factor of n, where n is the number of parallel devices. Figure 5 shows the equation for calculating output resistance. Combined Doubler/Inverter In the circuit of Figure 6, capacitors C1 and C2 form the inverter, while C3 and C4 form the doubler. C1 and C3 are the pump capacitors; C2 and C4 are the reservoir capacitors. Because both the inverter and doubler use part of the charge-pump circuit, loading either output causes both outputs to decline toward GND. Make sure the sum of the currents drawn from the two outputs does not exceed 30mA. Heavy Load Connected to a Positive Supply Under heavy loads, where a higher supply is sourcing current into OUT, the OUT supply must not be pulled above ground. Applications that sink heavy current into OUT require a Schottky diode (1N5817) between GND and OUT, with the anode connected to OUT (Figure 7). 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. Cascading Devices Two devices can be cascaded to produce an even larger negative voltage (Figure 4). The unloaded output voltage is normally -2 ✕ VIN, but this is reduced slightly by the output resistance of the first device multiplied by the quiescent current of the second. When cascading more than two devices, the output resistance rises significantly. For applications requiring larger negative voltages, see the MAX865 and MAX868 data sheets. 6 _______________________________________________________________________________________ SC70 Inverting Charge Pumps with Shutdown PRODUCTION METHOD MANUFACTURER SERIES PHONE FAX Surface-Mount Tantalum Surface-Mount Ceramic AVX TPS series 803-946-0690 803-626-3123 Matsuo 267 series 714-969-2491 714-960-6492 Sprague 593D, 595D series 603-224-1961 603-224-1430 AVX X7R 803-946-0690 803-626-3123 Matsuo X7R 714-969-2491 714-960-6492 Table 2. Capacitor Selection to Minimize Output Resistance Table 3. Capacitor Selection to Minimize Capacitor Size PART FREQUENCY (kHz) CAPACITOR (µF) TYPICAL ROUT (Ω) PART FREQUENCY (kHz) CAPACITOR (µF) TYPICAL ROUT (Ω) MAX1852 50 4.7 15 MAX1852 50 3.3 20 MAX1853 200 1 15 MAX1853 200 0.68 20 … 4 2 5 5 MAX1852 MAX1853 2 C1 6 1 MAX1852 MAX1853 C1 1 6 … 3 VOUT 2 D1, D2 = 1N4148 4 MAX1852 MAX1853 D1 6 1 VOUT = -VIN C2 3 C2 +VIN 3 4 5 C1 SHDN +VIN C2 D2 SHDN VOUT = -nVIN Figure 4. Cascading MAX1852/MAX1853s to Increase Output Voltage +VIN C1 2 C1 1 6 2 GND 2 MAX1852 MAX1853 MAX1852 MAX1853 1 6 … 3 SHDN Figure 6. Combined Doubler and Inverter 4 5 MAX1852 MAX1853 VOUT = (2VIN) (VFD1) - (VFD2) … 4 5 C4 C3 VOUT V+ RL OUT 1 3 VOUT = -VIN C2 Figure 7. Heavy Load Connected to a Positive Supply ROUT OF SINGLE DEVICE ROUT = NUMBER OF DEVICES Figure 5. Paralleling MAX1852/MAX1853s to Reduce Output Resistance Chip Information TRANSISTOR COUNT: 252 _______________________________________________________________________________________ 7 MAX1852/MAX1853 Table 1. Low-ESR Capacitor Manufacturers ________________________________________________________Package Information SC70, 6L.EPS MAX1852/MAX1853 SC70 Inverting Charge Pumps with Shutdown 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 © 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.