MAX1720 Switched Capacitor Voltage Inverter with Shutdown The MAX1720 is a CMOS charge pump voltage inverter that is designed for operation over an input voltage range of 1.15 V to 5.5 V with an output current capability in excess of 50 mA. The operating current consumption is only 67 mA, and a power saving shutdown input is provided to further reduce the current to a mere 0.4 mA. The device contains a 12 kHz oscillator that drives four low resistance MOSFET switches, yielding a low output resistance of 26 W and a voltage conversion efficiency of 99%. This device requires only two external 10 mF capacitors for a complete inverter making it an ideal solution for numerous battery powered and board level applications. The MAX1720 is available in the space saving TSOP−6 package. http://onsemi.com TSOP−6 SN SUFFIX CASE 318G 6 1 Features • • • • • • • • Operating Voltage Range of 1.15 V to 5.5 V Output Current Capability in Excess of 50 mA Low Current Consumption of 67 mA Power Saving Shutdown Input for a Reduced Current of 0.4 mA Operation at 12 kHz Low Output Resistance of 26 W Space Saving TSOP−6 Package Pb−Free Package is Available EACAYW G G 1 EAC = Device Code A = Assembly Location Y = Year W = Work Week G = Pb−Free Package (Note: Microdot may be in either location) Typical Applications • • • • • • • • MARKING DIAGRAM LCD Panel Bias Cellular Telephones Pagers Personal Digital Assistants Electronic Games Digital Cameras Camcorders Hand Held Instruments PIN CONNECTIONS Vout 1 6 C+ Vin 2 5 SHDN C− 3 4 GND −Vout Vin 1 6 2 5 3 4 (Top View) ORDERING INFORMATION Figure 1. Typical Application December, 2005 − Rev. 3 Package Shipping † MAX1720EUT TSOP−6 3000 Tape & Reel TSOP−6 (Pb−Free) 3000 Tape & Reel MAX1720EUTG This device contains 77 active transistors. © Semiconductor Components Industries, LLC, 2005 Device †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. 1 Publication Order Number: MAX1720/D MAX1720 MAXIMUM RATINGS* ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁ Rating Symbol Value Unit Input Voltage Range (Vin to GND) Vin −0.3 to 6.0 V Output Voltage Range (Vout to GND) Vout −6.0 to 0.3 V Output Current (Note 1) Iout 100 mA Output Short Circuit Duration (Vout to GND, Note 1) tSC Indefinite sec Operating Junction Temperature TJ 150 °C Power Dissipation and Thermal Characteristics Thermal Resistance, Junction−to−Air Maximum Power Dissipation @ TA = 70°C RqJA PD 256 313 °C/W mW Storage Temperature Tstg −55 to 150 °C Maximum ratings are those values beyond which device damage can occur. Maximum ratings applied to the device are individual stress limit values (not normal operating conditions) and are not valid simultaneously. If these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be affected. *ESD Ratings ESD Machine Model Protection up to 200 V, Class B ESD Human Body Model Protection up to 2000 V, Class 2 ELECTRICAL CHARACTERISTICS (Vin = 5.0 V, C1 = 10 mF, C2 = 10 mF, TA = −40°C to 85°C, typical values shown are for TA = 25°C unless otherwise noted. See Figure 14 for Test Setup.) Characteristic Symbol Min Typ Max Operating Supply Voltage Range (SHDN = Vin, RL = 10 k) Vin 1.5 to 5.5 1.15 to 6.0 − Supply Current Device Operating (SHDN = 5.0 V, RL = R) TA = 25°C TA = 85°C Iin Unit V mA − − 67 72 90 100 − − 0.4 1.6 − − 8.4 6.0 12 − 15.6 21 mA Supply Current Device Shutdown (SHDN = 0 V) TA = 25°C TA = 85°C ISHDN Oscillator Frequency TA = 25°C TA = −40°C to 85°C fOSC Output Resistance (Iout = 25 mA, Note 2) Rout − 26 50 W Voltage Conversion Efficiency (RL = R) VEFF 99 99.9 − % PEFF − 96 − % − − 0.6 Vin 0.5 Vin − − Power Conversion Efficiency (RL = 1.0 k) Shutdown Input Threshold Voltage (Vin = 1.5 V to 5.5 V) High State, Device Operating Low State, Device Shutdown kHz Vth(SHDN) Shutdown Input Bias Current High State, Device Operating, SHDN = 5.0 V TA = 2 TA = 85°C5°C Low State, Device Shutdown, SHDN = 0 V TA = 25°C TA = 85°C V pA IIH − − 5.0 100 − − − − 5.0 100 − − − 1.2 − IIL Wake−Up Time from Shutdown (RL = 1.0 k) tWKUP ms 1. Maximum Package power dissipation limits must be observed to ensure that the maximum junction temperature is not exceeded. TJ + TA ) (PD RqJA) 2. Capacitors C1 and C2 contribution is approximately 20% of the total output resistance. http://onsemi.com 2 MAX1720 90 Figure 14 Test Setup TA = 25°C 90 Rout, OUTPUT RESISTANCE (W) Rout, OUTPUT RESISTANCE (W) 100 80 70 60 50 40 30 20 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Figure 14 Test Setup 80 70 Vin = 1.5 V Vin = 2.0 V 60 50 Vin = 3.3 V 40 30 Vin = 5.0 V 20 −50 5.5 Vin, SUPPLY VOLTAGE (V) Vout, OUTPUT VOLTAGE RIPPLE (mVp−p) Iout, OUTPUT CURRENT (mA) 30 Vin = 4.75 V Vout = −4.00 V 20 Vin = 3.15 V Vout = −2.50 V 10 Vin = 1.90 V Vout = −1.50 V 5 Figure 14 Test Setup TA = 25°C 0 0 10 20 30 40 Vin = 4.75 V Vout = −4.00 V 300 250 200 Vin = 3.15 V Vout = −2.50 V 150 Vin = 1.90 V Vout = −1.50 V 100 50 0 10 20 30 40 C1, C2, C3, CAPACITANCE (mF) C1, C2, C3, CAPACITANCE (mF) Figure 4. Output Current vs. Capacitance Figure 5. Output Voltage Ripple vs. Capacitance Figure 14 Test Setup RL = ∞ 70 TA = 85°C 60 TA = 25°C 50 TA = −40°C 40 2.0 2.5 3.0 3.5 4.0 100 Figure 14 Test Setup TA = 25°C 350 0 fOSC, OSCILLATOR FREQUENCY (kHz) Iin, SUPPLY CURRENT (mA) 75 400 50 80 30 1.5 50 Figure 3. Output Resistance vs. Ambient Temperature 35 15 25 0 TA, AMBIENT TEMPERATURE (°C) Figure 2. Output Resistance vs. Supply Voltage 25 −25 4.5 5.0 13.0 Figure 14 Test Setup 12.5 Vin = 5.0 V 12.0 11.5 11.0 Vin = 1.5 V 10.5 10.0 −50 Vin = 3.3 V −25 0 25 50 75 Vin, SUPPLY VOLTAGE (V) TA, AMBIENT TEMPERATURE (°C) Figure 6. Supply Current vs. Supply Voltage Figure 7. Oscillator Frequency vs. Ambient Temperature http://onsemi.com 3 50 100 h, POWER CONVERSION EFFICIENCY (%) MAX1720 Vout, OUTPUT VOLTAGE (V) 0.0 100 Figure 14 Test Setup TA = 25°C Vin = 2.0 V −1.0 Vin = 3.3 V −2.0 −3.0 Vin = 5.0 V −4.0 −5.0 −6.0 10 20 30 40 50 90 80 70 Vin = 1.5 V 60 Vin = 2.0 V 50 40 0 10 20 30 40 Figure 8. Output Voltage vs. Output Current Figure 9. Power Conversion Efficiency vs. Output Current ISHDN, SHUTDOWN SUPPLY CURRENT (mA) Iout, OUTPUT CURRENT (mA) Figure 14 Test Setup Vin = 3.3 V Iout = 5.0 mA TA = 25°C 1.50 Vin = 5.0 V RL = 10 kW SHDN = GND Vin = 3.3 V 1.25 1.00 0.75 Vin = 1.5 V 0.50 0.25 −50 −25 0 25 50 75 TIME = 25 ms / Div. TA, AMBIENT TEMPERATURE (°C) Figure 10. Output Voltage Ripple and Noise Figure 11. Shutdown Supply Current vs. Ambient Temperature WAKEUP TIME FROM SHUTDOWN SHDN = 5.0V/Div. TA = 25°C 4.5 4.0 Low State, Device Shutdown 3.5 3.0 High State, Device Operating 2.5 2.0 1.5 0.5 1.0 1.5 2.0 2.5 Vin = 5.0 V RL = 1.0 kW TA = 25°C Vout = 1.0 V/Div. 3.0 TIME = 500 ms / Div. Vth(SHND), SHUTDOWN INPUT VOLTAGE THRESHOLD (V) Figure 12. Supply Voltage vs. Shutdown Input Voltage Threshold Figure 13. Wakeup Time From Shutdown http://onsemi.com 4 50 1.75 5.0 Vin, SUPPLY VOLTAGE (V) Vin = 5.0 V Vin = 3.3 V Iout, OUTPUT CURRENT (mA) OUTPUT VOLTAGE RIPPLE AND NOISE = 10 mV / Div. AC COUPLED 0 Figure 14 Test Setup TA = 25°C 100 MAX1720 Charge Pump Efficiency −Vout C + 2 6 1 The overall power conversion efficiency of the charge pump is affected by four factors: 1. Losses from power consumed by the internal oscillator, switch drive, etc. (which vary with input voltage, temperature and oscillator frequency). 2. I2R losses due to the on−resistance of the MOSFET switches on−board the charge pump. 3. Charge pump capacitor losses due to Equivalent Series Resistance (ESR). 4. Losses that occur during charge transfer from the commutation capacitor to the output capacitor when a voltage difference between the two capacitors exists. Most of the conversion losses are due to factors 2, 3 and 4. These losses are given by Equation 1. RL OSC Vin + 2 5 3 4 + C1 C3 C1 = C2 = C3 = 10 mF Figure 14. Test Setup/Voltage Inverter DETAILED OPERATING DESCRIPTION The MAX1720 charge pump converter inverts the voltage applied to the Vin pin. Conversion consists of a two−phase operation (Figure 15). During the first phase, switches S2 and S4 are open and S1 and S3 are closed. During this time, C1 charges to the voltage on Vin and load current is supplied from C2. During the second phase, S2 and S4 are closed, and S1 and S3 are open. This action connects C1 across C2, restoring charge to C2. S1 ƪ P + I out 2 LOSS(2,3,4) 1 (f OSC )C1 ) 8R SWITCH R out ^ I out 2 ) 4ESR C1 ) ESR C2 (eq. 1) The 1/(fOSC)(C1) term in Equation 1 is the effective output resistance of an ideal switched capacitor circuit (Figures 16 and 17). The losses due to charge transfer above are also shown in Equation 2. The output voltage ripple is given by Equation 3. S2 Vin C1 PLOSS + [ 0.5C 1 (Vin 2 * Vout 2) ) 0.5C2 (VRIPPLE 2 * 2VoutVRIPPLE)] fOSC (eq. 2) C2 S3 ƫ S4 V −Vout RIPPLE + Iout (f )(C ) OSC 2 ) 2(I out)(ESR ) C2 (eq. 3) From Osc f Vin Vout Figure 15. Ideal Switched Capacitor Charge Pump C1 APPLICATIONS INFORMATION C2 RL Output Voltage Considerations The MAX1720 performs voltage conversion but does not provide regulation. The output voltage will drop in a linear manner with respect to load current. The value of this equivalent output resistance is approximately 26 W nominal at 25°C with Vin = 5.0 V. Vout is approximately −5.0 V at light loads, and drops according to the equation below: Figure 16. Ideal Switched Capacitor Model REQUIV Vin VDROP + Iout Rout Vout + * (Vin * VDROP) Vout R EQUIV + f 1 C1 C2 RL Figure 17. Equivalent Output Resistance http://onsemi.com 5 MAX1720 Capacitor Selection Voltage Inverter In order to maintain the lowest output resistance and output ripple voltage, it is recommended that low ESR capacitors be used. Additionally, larger values of C1 will lower the output resistance and larger values of C2 will reduce output voltage ripple. (See Equation 3). Table 1 shows various values of C1, C2 and C3 with the corresponding output resistance values at 25°C. Table 2 shows the output voltage ripple for various values of C1, C2 and C3. The data in Tables 1 and 2 was measured not calculated. The most common application for a charge pump is the voltage inverter (Figure 14). This application uses two or three external capacitors. The C1 (pump capacitor) and C2 (output capacitor) are required. The input bypass capacitor, C3, may be necessary depending on the application. The output is equal to −Vin plus any voltage drops due to loading. Refer to Tables 1 and 2 for capacitor selection. The test setup used for the majority of the characterization is shown in Figure 14. Table 1. Output Resistance vs. Capacitance (C1 = C2 = C3), Vin = 4.75 V and Vout = −4.0 V Layout Considerations C1 = C2 = C3 (mF) Rout (W) 0.7 129.1 As with any switching power supply circuit, good layout practice is recommended. Mount components as close together as possible to minimize stray inductance and capacitance. Also, use a large ground plane to minimize noise leakage into other circuitry. 1.4 69.5 Capacitor Resources 3.3 37.0 7.3 26.5 10 25.9 24 24.1 Selecting the proper type of capacitor can reduce switching loss. Low ESR capacitors are recommended. The MAX1720 was characterized using the capacitors listed in Table 3. This list identifies low ESR capacitors for the voltage inverter application. 50 24 Table 3. Capacitor Types Manufacturer/Contact Table 2. Output Voltage Ripple vs. Capacitance (C1 = C2 = C3), Vin = 4.75 V and Vout = −4.0 V C1 = C2 = C3 (mF) Output Voltage Ripple (mV) 0.7 382 1.4 342 3.3 255 7.3 164 10 132 24 59 50 38 Part Types/Series AVX 843−448−9411 www.avxcorp.com TPS Cornell Dubilier 508−996−8561 www.cornell−dubilier.com ESRD Sanyo/Os−con 619−661−6835 www.sanyovideo.com/oscon.htm SN SVP Vishay 603−224−1961 www.vishay.com 593D 594 Input Supply Bypassing −Vout The input voltage, Vin should be capacitively bypassed to reduce AC impedance and minimize noise effects due to the switching internals in the device. If the device is loaded from Vout to GND, it is recommended that a large value capacitor (at least equal to C1) be connected from Vin to GND. If the device is loaded from Vin to Vout, a small (0.7 mF) capacitor between the pins is sufficient. OSC + Vin 6 1 + 2 5 + 3 4 Capacitors = 10 mF Figure 18. Voltage Inverter http://onsemi.com 6 MAX1720 The MAX1720 primary function is a voltage inverter. The device will convert 5.0 V into −5.0 V with light loads. Two capacitors are required for the inverter to function. A third capacitor, the input bypass capacitor, may be required depending on the power source for the inverter. The performance for this device is illustrated below. Vout, OUTPUT VOLTAGE (V) 0 TA = 25°C −1.0 Vin = 3.3 V −2.0 −3.0 Vin = 5.0 V −4.0 −5.0 −6.0 0 10 20 30 40 Iout, OUTPUT CURRENT (mA) 50 Figure 19. Inverter Load Regulation, Output Voltage vs. Output Current Vin −Vout 6 1 + + 2 6 1 OSC OSC + 5 + 2 5 3 4 + 3 4 Capacitors = 10 mF Figure 20. Cascaded Devices for Increased Negative Output Voltage Two or more devices can be cascaded for increased output voltage. Under light load conditions, the output voltage is approximately equal to −Vin times the number of stages. The converter output resistance increases dramatically with each additional stage. This is due to a reduction of input voltage to each successive stage as the converter output is loaded. Note that the ground connection for each successive stage must connect to the negative output of the previous stage. The performance characteristics for a converter consisting of two cascaded devices are shown below. 0 Vout, OUTPUT VOLTAGE (V) TA = 25°C −2.0 B −4.0 A −6.0 −8.0 −10.0 0 10 20 30 Iout, OUTPUT CURRENT (mA) 40 Figure 21. Cascade Load Regulation, Output Voltage vs. Output Current http://onsemi.com 7 Curve Vin (V) Rout (W) A 5.0 140 B 3.0 174 MAX1720 6 1 OSC Vin 2 + −Vout 5 + + 3 + + 4 Capacitors = 10 mF Figure 22. Negative Output Voltage Doubler A single device can be used to construct a negative voltage doubler. The output voltage is approximately equal to −2Vin minus the forward voltage drop of each external diode. The performance characteristics for the above converter are shown below. Note that curves A and C show the circuit performance with economical 1N4148 diodes, while curves B and D are with lower loss MBRA120E Schottky diodes. Vout, OUTPUT VOLTAGE (V) 0 TA = 25°C −2.0 Curve Vin (V) All Diodes Rout (W) A 3.0 1N4148 124 B 3.0 MBRA120E 115 C 5.0 1N4148 96 D 5.0 MBRA120E 94 A −4.0 B −6.0 C −8.0 D −10.0 30 10 20 Iout, OUTPUT CURRENT (mA) 0 40 Figure 23. Doubler Load Regulation, Output Voltage vs. Output Current 6 1 OSC Vin + 2 −Vout 5 + + 3 + + 4 Capacitors = 10 mF Figure 24. Negative Output Voltage Tripler http://onsemi.com 8 + + MAX1720 A single device can be used to construct a negative voltage tripler. The output voltage is approximately equal to −3Vin minus the forward voltage drop of each external diode. The performance characteristics for the above converter are shown below. Note that curves A and C show the circuit performance with economical 1N4148 diodes, while curves B and D are with lower loss MBRA120E Schottky diodes. 0 Vout, OUTPUT VOLTAGE −2.0 A −4.0 B −6.0 C −8.0 D −10.0 Curve Vin (V) All Diodes Rout (W) A 3.0 1N4148 267 B 3.0 MBRA120E 250 C 5.0 1N4148 205 D 5.0 MBRA120E 195 −12.0 −14.0 TA = 25°C −16.0 0 10 20 30 Iout, OUTPUT CURRENT 40 50 Figure 25. Tripler Load Regulation, Output Voltage vs. Output Current 6 1 OSC + Vin + 2 5 3 4 + Vout Capacitors = 10 mF Figure 26. Positive Output Voltage Doubler A single device can be used to construct a positive voltage doubler. The output voltage is approximately equal to 2Vin minus the forward voltage drop of each external diode. The performance characteristics for the above converter are shown below. Note that curves A and C show the circuit performance with economical 1N4148 diodes, while curves B and D are with lower loss MBRA120E Schottky diodes. 10.0 Vout, OUTPUT VOLTAGE (V) D 8.0 C 6.0 Curve Vin (V) All Diodes Rout (W) A 3.0 1N4148 32 B 3.0 MBRA120E 26 C 5.0 1N4148 26 D 5.0 MBRA120E 21 B 4.0 A 2.0 TA = 25°C 0 0 10 20 30 Iout, OUTPUT CURRENT (mA) 40 Figure 27. Doubler Load Regulation, Output Voltage vs. Output Current http://onsemi.com 9 MAX1720 6 1 OSC + Vin + 2 + Vout 5 + 3 + 4 Capacitors = 10 mF Figure 28. Positive Output Voltage Tripler A single device can be used to construct a positive voltage tripler. The output voltage is approximately equal to 3Vin minus the forward voltage drop of each external diode. The performance characteristics for the above converter are shown below. Note that curves A and C show the circuit performance with economical 1N4148 diodes, while curves B and D are with lower loss MBRA120E Schottky diodes. Vout, OUTPUT VOLTAGE (V) 14.0 D Curve Vin (V) All Diodes Rout (W) A 3.0 1N4148 111 B 3.0 MBRA120E 97 C 5.0 1N4148 85 D 5.0 MBRA120E 75 12.0 10.0 C 8.0 6.0 B 4.0 2.0 A TA = 25°C 0 0 10 20 30 Iout, OUTPUT CURRENT (mA) 40 Figure 29. Tripler Load Regulation, Output Voltage vs. Output Current −Vout + 6 1 OSC Vin + 2 5 + 100 k 3 4 Capacitors = 10 mF Figure 30. Load Regulated Negative Output Voltage http://onsemi.com 10 MAX1720 A zener diode can be used with the shutdown input to provide closed loop regulation performance. This significantly reduces the converter’s output resistance and dramatically enhances the load regulation. For closed loop operation, the desired regulated output voltage must be lower in magnitude than −Vin. The output will regulate at a level of −VZ + Vth(SHDN). Note that the shutdown input voltage threshold is typically 0.5 Vin and therefore, the regulated output voltage will change proportional to the converter’s input. This characteristic will not present a problem when used in applications with constant input voltage. In this case the zener breakdown was measured at 25 mA. The performance characteristics for the above converter are shown below. Note that the dashed curve sections represent the converter’s open loop performance. Vout, OUTPUT VOLTAGE (V) −1.0 TA = 25°C −2.0 A −3.0 B Curve Vin (V) Vz (V) Vout (V) A 3.3 V 4.5 −2.8 B 5.0 V 6.5 −3.8 −4.0 −5.0 0 10 20 30 40 50 60 Iout, OUTPUT CURRENT (mA) Figure 31. Load Regulation, Output Voltage vs. Output Current −Vout R1 6 1 + OSC Vin + 2 5 3 4 + R2 10 k Capacitors = 10 mF Figure 32. Line and Load Regulated Negative Output Voltage http://onsemi.com 11 MAX1720 An adjustable shunt regulator can be used with the shutdown input to give excellent closed loop regulation performance. The shunt regulator acts as a comparator with a precise input offset voltage which significantly reduces the converter’s output resistance and dramatically enhances the line and load regulation. For closed loop operation, the desired regulated output voltage must be lower in magnitude than −Vin. The output will regulate at a level of −Vref (R2/R1 + 1). The adjustable shunt regulator can be from either the TLV431 or TL431 families. The comparator offset or reference voltage is 1.25 V or 2.5 V respectively. The performance characteristics for the converter are shown below. Note that the dashed curve sections represent the converter’s open loop performance. 0 Iout = 25 mA R1 = 10 k R2 = 20 k TA = 25°C Vout, OUTPUT VOLTAGE (V) Vout, OUTPUT VOLTAGE (V) −1.0 A −2.0 −3.0 B −4.0 −1.0 −2.0 −3.0 TA = 25°C −5.0 0 10 20 30 40 50 60 70 −4.0 1.0 2.0 3.0 4.0 5.0 6.0 Iout, OUTPUT CURRENT (mA) Vin, INPUT VOLTAGE (V) Figure 33. Load Regulation, Output Voltage vs. Output Current Figure 34. Line Regulation, Output Voltage vs. Input Current Curve Vin (V) R1 (W) R2 (W) Vout (V) A 3.0 10 k 5.0 k −1.8 B 5.0 10 k 20 k −3.6 −Vout + 6 1 1 OSC Vin + 6 OSC 2 5 2 5 3 4 3 4 + + Capacitors = 10 mF Figure 35. Paralleling Devices for Increased Negative Output Current http://onsemi.com 12 MAX1720 An increase in converter output current capability with a reduction in output resistance can be obtained by paralleling two or more devices. The output current capability is approximately equal to the number of devices paralleled. A single shared output capacitor is sufficient for proper operation but each device does require it’s own pump capacitor. Note that the output ripple frequency will be complex since the oscillators are not synchronized. The performance characteristics for a converter consisting of two paralleled devices is shown below. Curve Vin (V) Rout (W) A 5.0 14.5 B 3.0 17 Vout, OUTPUT VOLTAGE (V) 0 TA = 25°C −1.0 B −2.0 −3.0 A −4.0 −5.0 0 10 20 30 40 50 60 70 80 90 100 Iout, OUTPUT CURRENT (mA) Figure 36. Parallel Load Regulation, Output Voltage vs. Output Current Q2 6 1 + Q1 2 5 3 4 −Vout + OSC Vin C1 C3 + C2 C1 = C2 = 470 mF C3 = 220 mF Q1 = PZT751 Q2 = PZT651 −Vout = Vin −VBE(Q1) − VBE(Q2) −2 VF Figure 37. External Switch for Increased Negative Output Current The output current capability of the MAX1720 can be extended beyond 600 mA with the addition of two external switch transistors and two Schottky diodes. The output voltage is approximately equal to −Vin minus the sum of the base emitter drops of both transistors and the forward voltage of both diodes. The performance characteristics for the converter are shown below. Note that the output resistance is reduced to 0.9 W. Vout, OUTPUT VOLTAGE (V) −2.2 −2.4 −2.6 −2.8 Vin = 5.0 V Rout = 0.9 W TA = 25°C −3.0 −3.2 0 0.1 0.2 0.3 0.4 Iout, OUTPUT CURRENT (mA) 0.5 0.6 Figure 38. Current Boosted Load Regulation, Output Voltage vs. Output Current http://onsemi.com 13 MAX1720 10 k R2 Q2 R1 C1 −Vout 6 1 + OSC Vin + 2 5 3 4 C2 + Q1 C3 C1 = C2 = 470 mF C3 = 220 mF Q1 = PZT751 Q2 = PZT651 Figure 39. Line and Load Regulated Negative Output Voltage with High Current Capability This converter is a combination of Figures 37 and 32. It provides a line and load regulated output of −2.36 V at up to 450 mA with an input voltage of 5.0 V. The output will regulate at a level of −Vref (R2/R1 + 1). The performance characteristics are shown below. Note, the dashed line is the open loop and the solid line is the closed loop performance. −1.0 Vout, OUTPUT VOLTAGE (V) Vout, OUTPUT VOLTAGE (V) −2.2 −2.4 −2.6 −2.8 Vin = 5.0 V Rout = 0.9 W R1 = 10 kW R2 = 9.0 kW TA = 25°C −3.0 −3.2 0 0.1 0.2 0.3 0.4 Iout, OUTPUT CURRENT (A) 0.5 0.6 Iout = 100 mA R1 = 10 k R2 = 9 kW TA = 25°C −1.2 −1.4 −1.6 −1.8 −2.0 −2.2 −2.4 3.0 Figure 40. Current Boosted Load Regulation, Output Voltage vs. Output Current 3.5 4.0 4.5 5.0 Vin, INPUT VOLTAGE (V) Figure 41. Current Boosted Line Regulation, Output Voltage vs. Input Voltage 50 Q2 C1 Vout 6 1 + 50 OSC Q1 Vin + 2 5 3 4 5.5 + C2 C3 Capacitors = 220 mF Q1 = PZT751 Q2 = PZT651 Figure 42. Positive Output Voltage Doubler with High Current Capability http://onsemi.com 14 6.0 MAX1720 The MAX1720 can be configured to produce a positive output voltage doubler with current capability in excess of 500 mA. This is accomplished with the addition of two external switch transistors and two Schottky diodes. The output voltage is approximately equal to 2Vin minus the sum of the base emitter drops of both transistors and the forward voltage of both diodes. The performance characteristics for the converter is shown below. Note that the output resistance is reduced to 1.9 W. Vout, OUTPUT VOLTAGE (V) 8.8 Vin = 5.0 V Rout = 1.9 W TA = 25°C 8.4 8.0 7.6 7.2 6.8 0 0.1 0.2 0.3 0.4 Iout, OUTPUT CURRENT (A) 0.5 0.6 Figure 43. Positive Doubler with Current Boosted Load Regulation, Output Voltage vs. Output Current R1 50 10 k Q2 50 OSC Q1 Vin + 2 5 3 4 R2 + 6 1 C3 Vout + C1 C2 Capacitors = 220 mF Q1 = PZT751 Q2 = PZT651 Figure 44. Line and Load Regulated Positive Output Voltage Doubler with High Current Capability This converter is a combination of Figures 42 and the shunt regulator to close the loop. In this case the anode of the regulator is connected to ground. This convert provides a line and load regulated output of 7.6 V at up to 300 mA with an input voltage of 5.0 V. The output will regulate at a level of Vref (R2/R1 + 1). The open loop configuration is the dashed line and the closed loop is the solid line. The performance characteristics are shown below. 8.0 Vin = 5.0 V Rout = 1.9 W Open Loop Rout = 0.5 W Closed Loop R1 = 10 k R2 = 51.3 kW TA = 25°C 8.4 8.0 Vout, OUTPUT VOLTAGE (V) Vout, OUTPUT VOLTAGE (V) 8.8 7.6 7.2 6.8 0 0.1 0.2 0.3 0.4 Iout, OUTPUT CURRENT (A) 0.5 0.6 7.0 6.0 5.0 4.0 Iout = 100 mA R1 = 10 k R2 = 51.3 kW TA = 25°C 3.0 2.0 1.0 1.0 Figure 45. Current Boosted Close Loop Load Regulation, Output Voltage vs. Output Current 2.0 3.0 4.0 Vin, INPUT VOLTGE (V) 5.0 Figure 46. Current Boosted Close Loop Line Regulation, Output Voltage vs. Input Voltage http://onsemi.com 15 6.0 MAX1720 Vin = −5.0 V + + OSC C C + 6 1 C 2 5 3 4 Vout = −2.5 V C + Capacitors = 10 mF Figure 47. Negative Input Voltage Splitter A single device can be used to split a negative input voltage. The output voltage is approximately equal to −Vin/2. The performance characteristics are shown below. Note that the converter has an output resistance of 10 W. Vout, OUTPUT VOLTAGE (V) −1.5 TA = 25°C Rout = 10 W −1.7 −1.9 −2.1 −2.3 −2.5 0 10 20 30 40 50 60 Iout, OUTPUT CURRENT (mA) 70 80 Figure 48. Negative Voltage Splitter Load Regulation, Output Voltage vs. Output Current −Vout R1 R2 6 1 + OSC Vin + 2 5 10 k 3 4 + + + +Vout Capacitors = 10 mF Figure 49. Combination of a Closed Loop Negative Inverter with a Positive Output Voltage Doubler http://onsemi.com 16 MAX1720 All of the previously shown converter circuits have only single outputs. Applications requiring multiple outputs can be constructed by incorporating combinations of the former circuits. The converter shown above combines Figures 26 and 32 to form a regulated negative output inverter with a non−regulated positive output doubler. The magnitude of −Vout is controlled by the resistor values and follows the relationship −Vref (R2/R1 + 1). Since the positive output is not within the feedback loop, its output voltage will increase as the negative output load increases. This cross regulation characteristic is shown in the upper portion of Figure 50. The dashed line is the open loop and the solid line is the closed loop configuration for the load regulation. The load regulation for the positive doubler with a constant load on the −Vout is shown in Figure 51. 10.0 Vout, OUTPUT VOLTAGE (V) Vout, OUTPUT VOLTAGE (V) 9.0 Positive Doubler Iout = 15 mA 8.0 −3.0 Negative Inverter −4.0 Rout = 45 W − Open Loop Rout = 2 W − Closed Loop R1 = 10 k, R2 = 20 k TA = 25°C −5.0 0 9.0 8.0 Negative Inverter Iout = 15 mA R1 = 10 kW R2 = 20 kW TA = 25°C 7.0 10 20 30 Iout, NEGATIVE INVERTER OUTPUT CURRENT (mA) 0 10 20 30 40 50 Iout, POSITIVE DOUBLER OUTPUT CURRENT (mA) Figure 51. Load Regulation, Output Voltage vs. Output Current Figure 50. Load Regulation, Output Voltage vs. Output Current + IC1 C1 C2 Vin −Vout SHDN GND C3 + GND + 0.5″ Inverter Size = 0.5 in x 0.2 in Area = 0.10 in2, 64.5 mm2 Figure 52. Inverter Circuit Board Layout, Top View Copper Side TAPING FORM Component Taping Orientation for TSOP−6 Devices USER DIRECTION OF FEED DEVICE MARKING PIN 1 Standard Reel Component Orientation (Mark Right Side Up) Tape & Reel Specifications Table Package TSOP−6 Tape Width (W) 8 mm Pitch (P) Part Per Full Reel Diameter 4 mm 3000 7 inches http://onsemi.com 17 MAX1720 PACKAGE DIMENSIONS TSOP−6 CASE 318G−02 ISSUE P NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. MAXIMUM LEAD THICKNESS INCLUDES LEAD FINISH THICKNESS. MINIMUM LEAD THICKNESS IS THE MINIMUM THICKNESS OF BASE MATERIAL. 4. DIMENSIONS A AND B DO NOT INCLUDE MOLD FLASH, PROTRUSIONS, OR GATE BURRS. D 6 HE 1 5 4 2 3 E b e q c A 0.05 (0.002) L A1 DIM A A1 b c D E e L HE q MIN 0.90 0.01 0.25 0.10 2.90 1.30 0.85 0.20 2.50 0° MILLIMETERS NOM MAX 1.00 1.10 0.06 0.10 0.38 0.50 0.18 0.26 3.00 3.10 1.50 1.70 0.95 1.05 0.40 0.60 2.75 3.00 10° − MIN 0.035 0.001 0.010 0.004 0.114 0.051 0.034 0.008 0.099 0° INCHES NOM 0.039 0.002 0.014 0.007 0.118 0.059 0.037 0.016 0.108 − MAX 0.043 0.004 0.020 0.010 0.122 0.067 0.041 0.024 0.118 10° SOLDERING FOOTPRINT* 2.4 0.094 1.9 0.075 0.95 0.037 0.95 0.037 0.7 0.028 1.0 0.039 SCALE 10:1 mm Ǔ ǒinches *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: N. American Technical Support: 800−282−9855 Toll Free Literature Distribution Center for ON Semiconductor USA/Canada P.O. Box 61312, Phoenix, Arizona 85082−1312 USA Phone: 480−829−7710 or 800−344−3860 Toll Free USA/Canada Japan: ON Semiconductor, Japan Customer Focus Center 2−9−1 Kamimeguro, Meguro−ku, Tokyo, Japan 153−0051 Fax: 480−829−7709 or 800−344−3867 Toll Free USA/Canada Phone: 81−3−5773−3850 Email: [email protected] http://onsemi.com 18 ON Semiconductor Website: http://onsemi.com Order Literature: http://www.onsemi.com/litorder For additional information, please contact your local Sales Representative. MAX1720/D 19-1439; Rev 2; 4/04 SOT23, Switched-Capacitor Voltage Inverters with Shutdown The ultra-small MAX1719/MAX1720/MAX1721 monolithic, CMOS charge-pump inverters accept input voltages ranging from +1.5V to +5.5V. The MAX1720 operates at 12kHz, and the MAX1719/MAX1721 operate at 125kHz. High efficiency, small external components, and logiccontrolled shutdown 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. A typical MAX1719/ MAX1720/MAX1721 application is generating a -5V supply from a +5V logic supply to power analog circuitry. All three parts come in a 6-pin SOT23 package and can deliver a continuous 25mA output current. For pin-compatible SOT23 switched-capacitor voltage inverters without shutdown (5-pin SOT23), see the MAX828/MAX829 and MAX870/MAX871 data sheets. For applications requiring more power, the MAX860/MAX861 deliver up to 50mA. For regulated outputs (up to -2 x VIN), refer to the MAX868. The MAX860/MAX861 and MAX868 are available in space-saving µMAX packages. Applications Local Negative Supply from a Positive Supply Features ♦ 1nA Logic-Controlled Shutdown ♦ 6-Pin SOT23 Package ♦ 99.9% Voltage Conversion Efficiency ♦ 50µA Quiescent Current (MAX1720) ♦ +1.5V to +5.5V Input Voltage Range ♦ 25mA Output Current ♦ Requires Only Two 1µF Capacitors (MAX1719/MAX1721) Ordering Information PART TEMP RANGE PINPACKAGE SOT TOP MARK MAX1719EUT -40°C to +85°C 6 SOT23-6 AACA MAX1720EUT -40°C to +85°C 6 SOT23-6 AABS MAX1721EUT -40°C to +85°C 6 SOT23-6 AABT Small LCD Panels GaAs PA Bias Supply Handy-Terminals, PDAs Battery-Operated Equipment Pin Configuration Typical Operating Circuit 1µF INPUT 1.5V to 5.5V C1+ TOP VIEW C1OUT IN MAX1721 NEGATIVE OUTPUT -1 · VIN 25mA OFF 1 IN 2 C1- 3 MAX1719 MAX1720 MAX1721 6 C1+ 5 SHDN (SHDN) 4 GND 1µF SHDN ON OUT GND SOT23-6 ( ) ARE FOR MAX1719 ________________________________________________________________ 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 MAX1719/MAX1720/MAX1721 General Description MAX1719/MAX1720/MAX1721 SOT23, Switched-Capacitor Voltage Inverters with Shutdown ABSOLUTE MAXIMUM RATINGS IN to GND .................................................................-0.3V to +6V OUT to GND .............................................................-6V to +0.3V C1+, SHDN, SHDN to GND .........................-0.3V to (VIN + 0.3V) C1- to GND...............................................(VOUT - 0.3V) to +0.3V OUT Output Current..........................................................100mA OUT Short Circuit to GND..............................................Indefinite Continuous Power Dissipation (TA = +70°C) 6-Pin SOT23 (derate 8.7mW/°C above +70°C).................696mW 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 (V IN = +5V, SHDN = GND (MAX1719), SHDN = IN (MAX1720/MAX1721), C1 = C2 = 10µF (MAX1720), C1 = C2 = 1µF (MAX1719/MAX1721), circuit of Figure 1, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Supply Voltage Range SYMBOL VIN Quiescent Supply Current (Note 3) ICC Shutdown Supply Current ISHDN Oscillator Frequency fOSC Voltage Conversion Efficiency Output Resistance (Note 1) OUT to GND Shutdown Resistance RO RO, SHDN VIH SHDN/ SHDN Input Logic Low VIL Wake-Up Time from Shutdown 2 IIL, IIH MIN TYP MAX1720 RL = 10kΩ TA = 0°C to + 85°C 1.5 5.5 MAX1719/MAX1721 RL = 10kΩ TA = +25°C 1.4 5.5 TA = 0°C to + 85°C 1.5 5.5 TA = +25°C 1.25 MAX TA = +25°C 50 90 MAX1719/MAX1721 350 650 0.001 1 SHDN = IN (MAX1719), TA = +25°C SHDN = GND (MAX1720/MAX1721) TA = +85°C TA = +25°C IOUT = 10mA 12 17 MAX1719/MAX1721 70 125 180 99 99.9 TA = +25°C 23 TA = 0°C to +85°C 4 12 2.0 +2.5V ≤ VIN ≤ +5.5V 0.6 VIN (MIN) ≤ VIN ≤ +2.5V 0.2 IOUT = 5mA Ω Ω V VIN - 0.2 -100 kHz % 50 65 SHDN = IN (MAX1719), SHDN = GND (MAX1720/MAX1721), OUT is internally forced to GND in shutdown SHDN/ SHDN = GND TA = +25°C or VIN TA = +85°C µA µA 7 VIN (MIN) ≤ VIN ≤ +2.5V V 0.02 MAX1720 +2.5V ≤ VIN ≤ +5.5V UNITS 5.5 MAX1720 IOUT = 0, TA = +25°C SHDN/ SHDN Input Logic High SHDN/ SHDN Bias Current CONDITIONS 0.05 10 MAX1720 800 MAX1719/MAX1721 80 _______________________________________________________________________________________ 100 V nA µs SOT23, Switched-Capacitor Voltage Inverters with Shutdown (V IN = +5V, SHDN = GND (MAX1719), SHDN = IN (MAX1720/MAX1721), C1 = C2 = 10µF (MAX1720), C1 = C2 = 1µF (MAX1719/MAX1721), circuit of Figure 1, TA = -40°C to +85°C, unless otherwise noted.) (Note 2) PARAMETER SYMBOL Supply Voltage Range VIN Quiescent Current (Note 3) ICC Oscillator Frequency fOSC Voltage Conversion Efficiency Output Resistance (Note 1) Output Current RO IOUT OUT to GND Shutdown Resistance RO, SHDN SHDN/ SHDN Input Logic High VIH SHDN/ SHDN Input Logic Low VIL CONDITIONS RL = 10kΩ MIN TYP MAX MAX1720 1.5 5.5 MAX1719/MAX1721 1.6 5.5 MAX1720 100 MAX1719/MAX1721 750 MAX1720 6 21 MAX1719/MAX1721 60 200 IOUT = 0 99 UNITS V µA kHz % IOUT = 10mA 65 Ω Continuous, long-term 25 mARMS SHDN = IN (MAX1719), SHDN = GND (MAX1720/MAX1721), OUT is internally forced to GND in shutdown 12 Ω +2.5V ≤ VIN ≤ +5.5V 2.1 VIN (MIN) ≤ VIN ≤ +2.5V V VIN - 0.2 +2.5V ≤ VIN ≤ +5.5V 0.6 VIN (MIN) ≤ VIN ≤ +2.5V 0.2 V Note 1: Capacitor contribution (ESR component plus (1/fOSC) · C) is approximately 20% of output impedance. Note 2: All specifications from -40°C to +85°C are guaranteed by design, not production tested. Note 3: The MAX1719/MAX1720/MAX1721 may draw high supply current during startup, up to the minimum operating supply voltage. To guarantee proper startup, the input supply must be capable of delivering 90mA more than the maximum load current. Typical Operating Characteristics (Circuit of Figure 1, VIN = +5V, SHDN = GND (MAX1719), SHDN = IN (MAX1720/MAX1721), C1 = C2 = C3, TA = +25°C, unless otherwise noted.) 90 -2 VIN = +3.3V -3 -4 VIN = +5V -5 VIN = +5V 80 EFFICIENCY (%) OUTPUT VOLTAGE (V) -1 100 70 60 VIN = +1.5V 50 VIN = +2V VIN = +3.3V 40 5 10 15 20 25 30 35 40 45 50 OUTPUT CURRENT (mA) 90 VIN = +5V 80 70 60 VIN = +1.5V 50 VIN = +3.3V VIN = +2V 40 30 30 20 20 10 10 0 0 0 100 EFFICIENCY (%) VIN = +2V MAX1720/21toc02 VIN = +1.5V MAX1720/21toc01 0 MAX1719/MAX1721 EFFICIENCY vs. OUTPUT CURRENT MAX1720 EFFICIENCY vs. OUTPUT CURRENT MAX1720/21toc03 OUTPUT VOLTAGE vs. OUTPUT CURRENT 0 5 10 15 20 25 30 35 40 45 50 OUTPUT CURRENT (mA) 0 5 10 15 20 25 30 35 40 45 50 OUTPUT CURRENT (mA) _______________________________________________________________________________________ 3 MAX1719/MAX1720/MAX1721 ELECTRICAL CHARACTERISTICS Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = +5V, SHDN = GND (MAX1719), SHDN = IN (MAX1720/MAX1721), C1 = C2 = C3, TA = +25°C, unless otherwise noted.) SUPPLY CURRENT vs. INPUT VOLTAGE MAX1719/ MAX1721 30 MAX1720 250 -40°C 150 MAX1720 -40°C 50 10 2.0 2.5 3.0 3.5 4.0 4.5 5.0 +85°C 0 1.5 5.5 2.0 2.5 INPUT VOLTAGE (V) FREQUENCY (kHz) VIN = +2V 40 VIN = +3.3V 30 35 5.0 60 MAX1720/21toc06 VIN = +1.5V -40 -15 85 VOUT MAX1719/ MAX1721 VOUT MAX1720 -15 -10 MAX1720 35 60 35 VIN = +4.75V, VOUT = -4.0V 30 OUTPUT CURRENT (mA) 60 MAX1719/MAX1721 MAX1720 OUTPUT VOLTAGE RIPPLE vs. CAPACITANCE 25 VIN = +3.15V, VOUT = -2.5V 20 15 10 10µs/div VIN = 3.3V, VOUT = -3.17V, IOUT = 5mA 20mV/div, AC-COUPLED 85 MAX1720 OUTPUT CURRENT vs. CAPACITANCE V SHDN 5V/div 35 OUTPUT NOISE AND RIPPLE MAX1720 START-UP FROM SHUTDOWN VOUT 2V/div 10 TEMPERATURE (°C) 100 10 -40 85 MAX1720/21toc10 VIN = +1.9V, VOUT = -1.5V 5 500 450 400 VIN = +4.75V, VOUT = -4.0V 350 300 VIN = +3.15V, VOUT = -2.5V 250 200 VIN = +1.9V, VOUT = -1.5V 150 100 50 0 4 5 5.5 TEMPERATURE (°C) RL = 1kΩ VIN = +3.3V 0 4.5 TEMPERATURE (°C) 500µs/div 10 MAX1720/21toc08 VIN = +1.5V VIN = +5V VIN = +5V VIN = +1.5V 10 10 VIN = +5V 15 MAX1720/21toc09 VIN = +5V -15 4.0 1000 MAX1720/21toc07 VIN = +1.5V 60 -40 3.5 20 PUMP FREQUENCY vs. TEMPERATURE 70 20 3.0 25 INPUT VOLTAGE (V) OUTPUT RESISTANCE vs. TEMPERATURE 50 MAX1720/21toc05 200 100 20 1.5 +85°C OUTPUT VOLTAGE RIPPLE (mVp-p) 40 300 MAX1720/21toc11 50 350 30 MAX1720/21toc12 60 MAX1719/ MAX1721 400 SUPPLY CURRENT (µA) 70 OUTPUT RESISTANCE (Ω) 450 MAX1720/21toc04 80 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE SHUTDOWN SUPPLY CURRENT (nA) OUTPUT RESISTANCE vs. INPUT VOLTAGE OUTPUT RESISTANCE (Ω) MAX1719/MAX1720/MAX1721 SOT23, Switched-Capacitor Voltage Inverters with Shutdown 0 0 5 10 15 20 25 30 35 40 45 50 CAPACITANCE (µF) 0 5 10 15 20 CAPACITANCE (µF) _______________________________________________________________________________________ 25 30 SOT23, Switched-Capacitor Voltage Inverters with Shutdown MAX1719/MAX1721 OUTPUT VOLTAGE RIPPLE vs. CAPACITANCE MAX1719/MAX1721 OUTPUT CURRENT vs. CAPACITANCE VIN = +4.75V, VOUT = -4.0V VSHDN 5V/div OUTPUT CURRENT (mA) 30 VOUT 2V/div MAX1720/21toc14 35 25 VIN = +3.15V, VOUT = -2.5V 20 15 10 VIN = +1.9V, VOUT = -1.5V 5 350 300 VIN = +4.75V, VOUT = -4.0V 250 200 VIN = +3.15V, VOUT = -2.5V 150 VIN = +1.9V, VOUT = -1.5V 100 50 0 0 0 50µs/div 400 MAX1720/21toc15 MAX1720/21toc13 OUTPUT VOLTAGE RIPPLE (mVp-p) MAX1721 START-UP FROM SHUTDOWN 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 CAPACITANCE (µF) CAPACITANCE (µF) RL = 1kΩ Pin Description PIN MAX1719 MAX1720 MAX1721 NAME FUNCTION 1 1 OUT 2 2 IN 3 3 C1- 4 4 GND Ground 5 – SHDN Noninverting Shutdown Input. Drive this pin low for normal operation; drive it high for shutdown mode. OUT is actively pulled to ground during shutdown. – 5 SHDN Inverting Shutdown Input. Drive this pin high for normal operation; drive it low for shutdown mode. OUT is actively pulled to ground during shutdown. 6 6 C1+ Inverting Charge-Pump Output Power-Supply Positive Voltage Input Negative Terminal of Flying Capacitor Positive Terminal of Flying Capacitor Detailed Description The MAX1719/MAX1720/MAX1721 capacitive 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 half- cycle, 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. _______________________________________________________________________________________ 5 MAX1719/MAX1720/MAX1721 Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = +5V, SHDN = GND (MAX1719), SHDN = IN (MAX1720/MAX1721), C1 = C2 = C3, TA = +25°C, unless otherwise noted.) MAX1719/MAX1720/MAX1721 SOT23, Switched-Capacitor Voltage Inverters with Shutdown f C1 1µF (10µF) INPUT 1.5V to 5.5V 2 6 C1+ 5 3 C1- IN OUT C3 1µF (10µF) ON OFF V+ 1 RL MAX1719* MAX1721 SHDN NEGATIVE OUTPUT -1 · VIN 25mA C2 C1 RL C2 1µF (10µF) Figure 3a. Switched-Capacitor Model GND 4 REQUIV V+ NOTE: ( ) CAPACITORS ARE FOR MAX1720. *ON/OFF POLARITY OF SHDN IS REVERSED FOR MAX1719. VOUT 1 REQUIV = f × C1 Figure 1. Typical Application Circuit S1 VOUT C2 RL S2 IN Figure 3b. Equivalent Circuit C1 S3 S4 where the output impedance is roughly approximated by: C2 VOUT = -(VIN) Figure 2. Ideal Voltage Inverter Charge-Pump Output The MAX1719/MAX1720/MAX1721 are not voltage regulators: the charge pumps’ output resistance is approximately 23Ω at room temperature (with VIN = +5V), and VOUT approaches -5V when lightly loaded. VOUT will droop toward GND as load current increases. The droop of the negative supply (VDROOP-) equals the current draw from OUT (IOUT) times the negative converter’s output resistance (RO): VDROOP- = IOUT x RO The negative output voltage will be: VOUT = -(VIN - VDROOP-) Efficiency Considerations The efficiency of the MAX1719/MAX1720/MAX1721 is dominated by its quiescent supply current (IQ) at low output current and by its output impedance (ROUT) at higher output current; it is given by: η≅ 6 IOUT IOUT + IQ IOUT × ROUT 1 − VIN ROUT ≅ 1 (fOSC ) × C1 + 2RSW + 4ESRC1 + ESRC2 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 resistances (typically 8Ω to 9Ω at VIN = +5V). The typical output impedance is more accurately determined from the Typical Operating Characteristics. Shutdown Mode The MAX1719/MAX1720/MAX1721 have a logic-controlled shutdown input. Driving SHDN low places the MAX1720/MAX1721 in a low-power shutdown mode. The MAX1719’s shutdown input is inverted from that of the MAX1720/MAX1721. Driving SHDN high places the MAX1719 in a low-power shutdown mode. The chargepump switching halts, supply current is reduced to 1nA, and OUT is actively pulled to ground through a 4Ω resistance. Applications Information Capacitor Selection To maintain the lowest output resistance, use capacitors with low ESR (Table 1). The charge-pump output resistance is a function of C1’s and C2’s ESR. Therefore, minimizing the charge-pump capacitor’s ESR minimizes the total output resistance. Table 2 gives suggested capacitor values for minimizing output resistance or minimizing capacitor size. _______________________________________________________________________________________ SOT23, Switched-Capacitor Voltage Inverters with Shutdown … 2 3 4 C1 6 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: VRIPPLE = MAX1719 MAX1720 MAX1721 “1” +VIN 2 3 4 C1 1 6 MAX1719 MAX1720 MAX1721 “n” 1 … 5 C2 SHDN (MAX1719) SHDN (MAX1720/ MAX1721) VOUT C2 5 VOUT = -nVIN Figure 4. Cascading MAX1719s or MAX1720s or MAX1721s to Increase Output Voltage IOUT + 2 × IOUT × ESRC2 2 × fOSC × C2 Cascading Devices Two devices can be cascaded to produce an even larger negative voltage (Figure 4). The unloaded output voltage is normally -2 x 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 dramatically. For applications requiring larger negative voltages, see the MAX865 and MAX868 data sheets. The maximum load current and startup current of the nth cascaded circuit must not exceed the maximum output current capability of the (n - 1)th circuit to ensure proper startup. Input Bypass Capacitor (C3) Bypass the incoming supply to reduce its AC impedance and the impact of the MAX1719/MAX1720/MAX1721’s 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. Table 1. Low-ESR Capacitor Manufacturers PRODUCTION METHOD Surface-Mount Tantalum Surface-Mount Ceramic MANUFACTURER SERIES PHONE FAX 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 for Minimum Output Resistance or Capacitor Size fOSC CAPACITORS TO MINIMIZE OUTPUT RESISTANCE (RO = 23Ω, TYP) C1 = C2 MAX1720 12kHz 10µF 3.3µF MAX1719/MAX1721 125kHz 1µF 0.33µF PART CAPACITORS TO MINIMIZE SIZE (RO = 40Ω, TYP) C1 = C2 _______________________________________________________________________________________ 7 MAX1719/MAX1720/MAX1721 Flying Capacitor (C1) Increasing the flying capacitor’s value reduces the output resistance. 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. MAX1719/MAX1720/MAX1721 SOT23, Switched-Capacitor Voltage Inverters with Shutdown 2 3 C1 4 6 SHDN (MAX1719) SHDN (MAX1720/ MAX1721) MAX1719 MAX1720 MAX1721 “1” SHDN (MAX1719) SHDN (MAX1720) (MAX1721) … +VIN 2 3 4 C1 1 6 … 5 +VIN 5 3 MAX1719 MAX1720 MAX1721 “n” C1 1 4 VOUT 6 D1, D2 = 1N4148 2 MAX1719 MAX1720 MAX1721 D1 1 VOUT = -VIN 5 VOUT = -VIN C2 D2 C2 RO OF SINGLE DEVICE RO = NUMBER OF DEVICES C4 C3 Figure 5. Paralleling MAX1719s or MAX1720s or MAX1721s to Reduce Output Resistance Figure 6. Combined Doubler and Inverter Paralleling Devices Paralleling multiple MAX1719s, MAX1720s, or MAX1721s 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 25mA. VOUT = (2VIN) (VFD1) - (VFD2) GND MAX1719 MAX1720 MAX1721 4 V+ RL OUT 1 Figure 7. Heavy Load Connected to a Positive Supply 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. 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 Chip Information TRANSISTOR COUNT: 85 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 © 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.