19-1439; Rev 1; 5/99 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 · 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 (MAX1719/MAX1720) ♦ +1.5V to +5.5V Input Voltage Range ♦ 25mA Output Current ♦ Requires Only Two 1µF Capacitors (MAX1719/MAX1721) Ordering Information 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 PART 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 1µF SHDN ON OUT MAX1719 MAX1720 MAX1721 6 C1+ 5 SHDN (SHDN) 4 GND GND SOT23-6 ( ) ARE FOR MAX1719 ________________________________________________________________ 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 1-800-835-8769. 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, 10sec) .............................+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 = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Supply Voltage Range SYMBOL VIN Quiescent Supply Current 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 MAX MAX1720 RL = 10kΩ TA = +25°C 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 5.5 MAX1720 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 7 12 17 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 -100 kHz Ω Ω V VIN - 0.2 SHDN/ SHDN = GND TA = +25°C or VIN TA = +85°C µA % 50 65 SHDN = IN (MAX1719), SHDN = GND (MAX1720/MAX1721), OUT is internally forced to GND in shutdown VIN (MIN) ≤ VIN ≤ +2.5V V µA MAX1719/MAX1721 +2.5V ≤ VIN ≤ +5.5V UNITS 0.02 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 CONDITIONS MAX1719/MAX1721 1.6 5.5 RL = 10kΩ Quiescent Current ICC MAX1719/MAX1720/MAX1721 Oscillator Frequency fOSC Output Current RO IOUT OUT to GND Shutdown Resistance RO, SHDN SHDN/ SHDN Input Logic High VIH SHDN/ SHDN Input Logic Low VIL MAX 5.5 VIN Output Resistance (Note 1) TYP 1.5 Supply Voltage Range Voltage Conversion Efficiency MIN MAX1720 UNITS V 100 µA 750 MAX1720 6 21 MAX1719/MAX1721 60 200 IOUT = 0 99 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 2.0 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. 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 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+ IN OUT C3 1µF (10µF) 5 ON OFF V+ 3 C1- 1 RL MAX1719* MAX1721 SHDN NEGATIVE OUTPUT -1 · VIN 25mA VOUT 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 C2 C2 RL S2 IN Figure 3b. Equivalent Circuit C1 S3 S4 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 · RO The negative output voltage will be: VOUT = -(VIN - VDROOP-) Efficiency Considerations The power efficiency of a switched-capacitor voltage converter is affected by three factors: the internal losses in the converter IC, the losses in the power switches, and the resistive losses of the pump capacitors. The total power loss is: ΣPLOSS = PINTERNAL LOSSES +PSWITCH LOSSES 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 other 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: PSWITCH LOSSES + PPUMP CAPACITOR LOSSES = IOUT RO ≅ ( 2 1 fOSC ⋅ RO ) ⋅ C1 + 2RSWITCHES + 4ESRC1 + ESRC2 where fOSC is the oscillator frequency. The first term is the effective resistance from an ideal switchedcapacitor circuit. See Figures 3a and 3b. 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. +PPUMP CAPACITOR LOSSES 6 _______________________________________________________________________________________ SOT23, Switched-Capacitor Voltage Inverters with Shutdown … Capacitor Selection 2 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. 3 6 IOUT ⋅ C2 +2 4 C1 1 5 6 C2 SHDN (MAX1719) SHDN (MAX1720/ MAX1721) MAX1719 MAX1720 MAX1721 “n” 1 VOUT C2 5 VOUT = -nVIN Figure 4. Cascading MAX1719s or MAX1720s or MAX1721s to Increase Output Voltage 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. 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: 2 x fOSC MAX1719 MAX1720 MAX1721 “1” 2 3 … 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. VRIPPLE = 4 C1 +VIN 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 dramatically. For applications requiring larger negative voltages, see the MAX865 and MAX868 data sheets. ⋅ IOUT ⋅ ESRC2 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. 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 Applications Information MAX1719/MAX1720/MAX1721 SOT23, Switched-Capacitor Voltage Inverters with Shutdown 2 2 3 C1 4 6 SHDN (MAX1719) SHDN (MAX1720/ MAX1721) MAX1719 MAX1720 MAX1721 “1” SHDN (MAX1719) SHDN (MAX1720/ MAX1721) … +VIN 3 4 C1 1 6 … 5 +VIN 5 3 MAX1719 MAX1720 MAX1721 “n” C1 1 VOUT 4 6 D1, D2 = 1N4148 2 MAX1719 MAX1720 MAX1721 D1 1 VOUT = -VIN C2 5 VOUT = -VIN 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 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.