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| 19-0227; Rev 2; 5/96 NUAL KIT MA ATION ET EVALU TA SHE WS DA FOLLO Regulated 5V Charge-Pump DC-DC Converter ____________________________Features o Regulated 5V 4% Charge Pump o Output Current Guaranteed over Temperature 20mA (VIN 2V) 50mA (VIN 3V) o 2V to 3.6V Input Range o No Inductors; Very Low EMI Noise o Ultra-Small Application Circuit (0.1in2) o Uses Small, Inexpensive Capacitors o 500kHz Internal Oscillator o Logic-Controlled 1A Max Shutdown Supply Current o Shutdown Disconnects Load from Input o 8-Pin DIP and SO Packages _______________General Description The MAX619 step-up charge-pump DC-DC converter delivers a regulated 5V 4% output at 50mA over temperature. The input voltage range is 2V to 3.6V (two battery cells). The complete MAX619 circuit fits into less than 0.1in2 of board space because it requires only four external capacitors: two 0.22F flying capacitors, and 10F capacitors at the input and output. Low operating supply current (150A max) and low shutdown supply current (1A max) make this device ideal for small, portable, and battery-powered applications. When shut down, the load is disconnected from the input. The MAX619 is available in 8-pin DIP and SO packages. MAX619 ________________________Applications Two Battery Cells to 5V Conversion Local 3V-to-5V Conversion Portable Instruments & Handy-Terminals Battery-Powered Microprocessor-Based Systems 5V Flash Memory Programmer Minimum Component DC-DC Converters Remote Data-Acquisition Systems Compact 5V Op-Amp Supply Regulated 5V Supply from Lithium Backup Battery Switching Drive Voltage for MOSFETs in Low-Voltage Systems _______________Ordering Information PART MAX619CPA MAX619CSA MAX619C/D MAX619EPA MAX619ESA MAX619MJA TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -55C to +125C PIN-PACKAGE 8 Plastic DIP 8 SO Dice* 8 Plastic DIP 8 SO 8 CERDIP * Dice are specified at TA = +25 C. __________________Pin Configuration TOP VIEW __________Typical Operating Circuit INPUT 2V to 3.6V 10F C1+ 1 IN 2 OUT 3 C2+ 4 8 C17 SHDN ON/OFF IN OUT 10F OUTPUT 5V, 20mA MAX619 SHDN C1+ 0.22F C1GND C2C2+ 0.22F MAX619 6 GND 5 C2- DIP/SO ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 Regulated 5V Charge-Pump DC-DC Converter MAX619 ABSOLUTE MAXIMUM RATINGS VIN to GND ............................................................-0.3V to +5.5V VOUT to GND .........................................................-0.3V to +5.5V SHDN to GND ..............................................-0.3V to (VIN + 0.3V) IOUT Continuous (Note 1)..................................................120mA Continuous Power Dissipation (TA = +70C) Plastic DIP (derate 9.09mW/C above +70C) ............727mW SO (derate 5.88mW/C above +70C) .........................471mW CERDIP (derate 8.00mW/C above +70C) .................640mW Note 1: The MAX619 is not short-circuit protected. 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. Operating Temperature Ranges MAX619C_ _ .......................................................0C to +70C MAX619E_ _ ....................................................-40C to +85C MAX619MJA ..................................................-55C to +125C Storage Temperature Range .............................-65C to +165C Lead Temperature (soldering, 10sec) .............................+300C ELECTRICAL CHARACTERISTICS (VIN = 2V to 3.6V, C1 = C2 = 0.22F, C3 = C4 = 10F, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Input Voltage SYMBOL VIN 2.0V VIN 3.6V, 0mA IOUT 20mA Output Voltage VOUT 3.0V VIN 3.6V, 0mA IOUT 50mA, MAX619C 3.0V VIN 3.6V, 0mA IOUT 45mA, MAX619E 3.0V VIN 3.6V, 0mA IOUT 40mA, MAX619M Output Ripple No-Load Supply Current Shutdown Supply Current Efficiency Switching Frequency SHDN Input Threshold SHDN Input Current VIH VIL IIH VSHDN = VIN MAX619C/E MAX619M Eff VRIPPLE IIN No load to full load 2V VIN 3.6V, IOUT = 0mA 2V VIN 3.6V, IOUT = 0mA, VSHDN = VIN MAX619C/E MAX619M CONDITIONS MIN 2 TYP MAX 3.6 UNITS V 4.8 5.0 5.2 V 100 75 0.02 82 82 80 500 0.7 x VIN 0.4 1 10 170 1 10 mV A A VIN = 3V, IOUT = 20mA VIN = 3V, IOUT = 30mA VIN = 2V, IOUT = 20mA At full load % kHz V A 2 ________________________________________________________________________________________ Regulated 5V Charge-Pump DC-DC Converter __________________________________________Typical Operating Characteristics (TA = +25C, unless otherwise noted.) EFFICIENCY vs. OUTPUT CURRENT AND INPUT VOLTAGE 90 85 VIN = 1.8V VIN = 3.0V 200 180 160 140 MAX619 INPUT CURRENT vs. OUTPUT CURRENT D E C IIN (A) B VIN IOUT MAX NO-LOAD INPUT CURRENT vs. INPUT VOLTAGE 1000 G F SHDN = 0V 100 EFFICIENCY (%) 80 IIN (mA) VIN = 2.0V 75 VIN = 3.3V 70 65 VIN = 2.7V 60 1 10 IOUT (mA) 100 VIN = 3.6V VIN = 2.4V 120 100 80 60 40 20 0 10 A A B C D E F G 1.8 2.0 2.4 2.7 3.0 3.6 3.3 18 36 41 64 72 94 100 1.0 0.1 0.01 1.5 2.0 SHDN = VIN 2.5 3.0 3.5 4.0 4.5 0 10 20 30 40 50 60 70 80 90 100 IOUT (mA) OUTPUT VOLTAGE vs. INPUT VOLTAGE 5.06 90 VIN (V) EFFICIENCY vs. INPUT VOLTAGE IOUT = 10mA OUTPUT VOLTAGE vs. OUTPUT CURRENT 5.05 VIN = 3.3V 5.00 4.95 4.90 4.85 4.80 4.75 1 10 100 VIN = 1.8V VIN = 2.0V VIN = 2.4V, 2.7V VIN = 3.0V = 3.6V VIN = 3.6V 5.04 5.02 85 EFFICIENCY (%) IOUT = 20mA VOUT (V) 80 75 70 65 60 VOUT (V) 5.00 4.98 4.96 4.94 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 1.5 2.0 2.5 3.0 3.5 4.0 IOUT (mA) VIN (V) VIN (V) LOAD-TRANSIENT RESPONSE LINE-TRANSIENT RESPONSE (IOUT = 20mA) 2ms/div TOP TRACE: OUTPUT CURRENT, 0mA to 25mA, 10mA/div BOTTOM TRACE: OUTPUT VOLTAGE, 5mV/div, AC-COUPLED 2ms/div RLOAD = 250, VOUT = 5V, IOUT = 20mA TOP TRACE: VIN = 2V to 3V, 1V/div BOTTOM TRACE: OUTPUT VOLTAGE, 50mV/div, AC-COUPLED ________________________________________________________________________________________ 3 Regulated 5V Charge-Pump DC-DC Converter MAX619 _____________________Pin Description PIN NAME 1 2 3 4 5 6 7 8 C1+ IN OUT C2+ C2GND SHDN C1FUNCTION Positive Terminal for C1 Input Supply Voltage +5V Output Voltage. VOUT = 0V when in shutdown mode. Positive Terminal for C2 Negative Terminal for C2 Ground Active-High CMOS Logic-Level Shutdown Input Negative Terminal for C1 _______________Detailed Description Operating Principle The MAX619 provides a regulated 5V output from a 2V to 3.6V (two battery cells) input. Internal charge pumps and external capacitors generate the 5V output, eliminating the need for inductors. The output voltage is regulated to 5V 4% by a pulse-skipping controller that turns on the charge pump when the output voltage begins to droop. To maintain the greatest efficiency over the entire input voltage range, the MAX619's internal charge pump operates as a voltage doubler when VIN ranges from 3.0V to 3.6V, and as a voltage tripler when VIN ranges from 2.0V to 2.5V. When VIN ranges from 2.5V to 3.0V, the MAX619 switches between doubler and tripler mode on alternating cycles, making a 2.5 x VIN charge pump. To further enhance efficiency over the input range, an internal comparator selects the higher of VIN or V OUT to run the MAX619's internal circuitry. Efficiency with VIN = 2V and IOUT = 20mA is typically 80%. Figure 1 shows a detailed block diagram of the MAX619. In tripler mode, when the S1 switches close, the S2 switches open and capacitors C1 and C2 charge up to VIN. On the second half of the cycle, C1 and C2 are connected in series between IN and OUT when the S1 switches open and the S2 switches close, as shown in Figure 1. In doubler mode, only C2 is used. During one oscillator cycle, energy is transferred from the input to the charge-pump capacitors, and then from the charge-pump capacitors to the output capacitor and load. The number of cycles within a given time frame increases as the load increases or as the input supply voltage decreases. In the limiting case, the charge pumps operate continuously, and the oscillator frequency is nominally 500kHz. Shutdown Mode The MAX619 enters low-power shutdown mode when SHDN is a logic high. SHDN is a CMOS-compatible input. In shutdown mode, the charge-pump switching action is halted, OUT is disconnected from IN, and VOUT falls to 0V. Connect SHDN to ground for normal operation. When VIN = 3.6V, VOUT typically reaches 5V in 0.5ms under no-load conditions after SHDN goes low. 4 ________________________________________________________________________________________ Regulated 5V Charge-Pump DC-DC Converter MAX619 IN C3 10F P MAX619 IC POWER C2+ S1A * S2A P OUT C4 C2 0.22F IN C2S1B VIN/VOUT 10F CONTROL LOGIC S2B SWITCH CONTROL BUS FB C1+ VREF C1 0.22F C1- S1C SD S2C S1D SHDN GND * SWITCHES SHOWN IN TRIPLER MODE, DISCHARGE CYCLE Figure 1. Block Diagram ________________________________________________________________________________________ 5 Regulated 5V Charge-Pump DC-DC Converter MAX619 __________Applications Information Capacitor Selection Charge-Pump Capacitors C1 and C2 The values of charge-pump capacitors C1 and C2 are critical to ensure adequate output current and avoid excessive peak currents. Use values in the range of 0.22F to 1.0F. Larger capacitors (up to 50F) can be used, but larger capacitors will increase output ripple. Ceramic or tantalum capacitors are recommended. Input and Output Capacitors, C3 and C4 The type of input bypass capacitor (C3) and output filter capacitor (C4) used is not critical, but it does affect performance. Tantalums, ceramics, or aluminum electrolytics are suggested. For smallest size, use Sprague 595D106X0010A2 surface-mount capacitors, which measure 3.7mm x 1.8mm (0.146in x 0.072in). For lowest ripple, use large, low effective-series-resistance (ESR) ceramic or tantalum capacitors. For lowest cost, use aluminum electrolytic or tantalum capacitors. Figure 2 shows the component values for proper operation using minimal board space. The input bypass capacitor (C3) and output filter capacitor (C4) should both be at least 10F when using aluminum electrolytics or Sprague's miniature 595D series of tantalum chip capacitors. When using ceramic capacitors, the values of C3 and C4 can be reduced to 2F and 1F, respectively. If the input supply source impedance is very low, C3 may not be necessary. Many capacitors exhibit 40% to 50% variation over temperature. Compensate for capacitor temperature coefficient by selecting a larger nominal value to ensure proper operation over temperature. Table 1 lists capacitor suppliers. 1 C2 0.22F C1+ C2+ 4 C1 0.22F 8 2 MAX619 C1- IN GND C2- SHDN OUT 5 7 3 2 CELLS C3 10F 6 5V 4% @ 20mA C4 10F Figure 2. Two-Cell to 5V Application Circuit Table 1. Capacitor Suppliers SUPPLIER PHONE NUMBER FAX NUMBER CAPACITOR GRM42-6Z5U10M50 Murata Erie (814) 237-1431 (814) 238-0490 GRM42-6Z5U22M50 RPI123Z5U105M50V RPE121Z5U104M50V Sprague Electric (smallest size) (603) 224-1961 (207) 327-4140 (603) 224-1430 (207) 324-7223 595D106X0010A2 CAPACITOR TYPE* 0.1F ceramic (SM) 0.22F ceramic (SM) 1.0F ceramic (TH) 0.1F ceramic (TH) 10F tantalum (SM) * Note: (SM) denotes surface-mount component, (TH) denotes through-hole component. 6 ________________________________________________________________________________________ Regulated 5V Charge-Pump DC-DC Converter MAX619 Layout Considerations The MAX619's high oscillator frequency makes good layout important. A good layout ensures stability and helps maintain the output voltage under heavy loads. For best performance, use very short connections to the capacitors. ___________________Chip Topography C1+ C1- Paralleling Devices Two MAX619s can be placed in parallel to increase output drive capability. The IN, OUT, and GND pins can be paralleled, but C1 and C2 pins cannot. The input bypass capacitor and output filter capacitor are, to some extent, shared when two circuits are paralleled. If the circuits are physically close together, it may be possible to use a single bypass and a single output capacitor, each with twice the value of the single circuit. If the MAX619s cannot be placed close together, use separate bypass and output capacitors. The amount of output ripple observed will determine whether single input bypass and output filter capacitors can be used. IN SHDN 0.115" (2.921mm) OUT GND C2+ C20.072" (1.828mm) TRANSISTOR COUNT: 599; SUBSTRATE CONNECTED TO GND. MAX619 IN GND INPUT 5V, 40mA OUT MAX619 IN GND OUT Figure 3. Paralleling Two MAX619s ________________________________________________________________________________________ 7 |
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