General Description The MAX641/MAX642/MAX643 step-up switching regu- lators are designed for minimum component DC-DC converter circuits in the 5mW to 10W range. Low-power applications require only an output filter ca- pacitor and a small, low-cost inductor. An additional MOSFET or bipolar transistor is needed for high-power applications. Low battery detection circuitry is included on chip. The MAX641/642/643 are preset for +5V, +12V, and +15V outputs, respectively. However, the regulators can be set to other levels by adding 2 resistors. Maxim manufactures a broad line of step-up, step-down, and inverting DC-DC converters with features such as logic- level shutdown, adjustable oscillator frequency, and ex- ternal MOSFET drive. See Table 3 for a summary of other DC-DC converter products Applications Simple, High-Efficiency DC-DC Converters Uninterruptible Board-Level Power Supplies Power Conditioning for Battery Systems Portable Instruments and Communications Pin Configuration SUA XAL/VI Fixed Output 10W CMOS Step-Up Switching Regulators Features @ Fixed +5V, +12V, +15V Output Voltages @ Adjustable Output with 2 Resistors @ On-Chip Driver for High-Power External MOSFET @ 135A Typ Operating Current @ 80% Typ Efficiency @ 8-Pin Narrow DIP and Narrow SO Packages Ordering Information v9/Ev9/LP9OXVN PART* ____TEMP.RANGE __ PIN-PACKAGE [ waxed ixCPA OCto+70C 8 Plastic DIP MAX641XCSA_ OC to +70C = 8 Narrow SO MAX64 1XC/D OCto+70C Dice | LMAXGSIXEPA _ -40C10+85C 8 Plastic DIP | MAX641XESA 40 C to +85'C 8 Narrow SO | MAX641XEJA -40'C to +85C _ 8CERDIP _ | MAX641XMJA _-55C to +125 = 8 CERDIP | MAX642XCPA_ =O to 470C__B Plastic DIP | MAX642XCSA_ OO to +70 C 8 Narrow SO MAX642XC/D O'to+70C ___Dice | MAX642XEPA_ -40 Cl0+85C 8 Plastic ast DIP | MAX642XESA_ 40 Cio +85C 8 Narrow SO | MAXG42xEJA __ 40C to +85 C _ 8 CERDIP | _ MAX642XMJA 5S Cto+125C 8 CERDIP | *X = A for 5% Output Accuracy. X = B for 10% Output Accuracy Ordering information continued on last page Typical Operating Circuit a w TOP VIEW | | 18H | - run) | | | av 6 | | . a EXT | | Ll [4] naan yg | comp | |. i | | (BO | MAX64T 7 | VFB aroha ano ty MAX642 [6 | XI || | | Lx MAX643 VOUT vOUT}# = - eV | ly a | | Lal GND VFB | | | | 3 eps 3380pt | | @ e - ? | DIP/SO | | +5V OUTPUT DC-DC CONVERTER | | en | mM aA A ay mM Maxim integrated F Products 1 Cail toll free 1-800-998-8800 for free samples o or r literature.MAX641/642/643 Fixed Output 10W CMOS Step-up Switching Regulators ABSOLUTE MAXIMUM RATINGS Supply Voltage, VOUT 2.000... +18V Operating Temperature Output Voltage, LX andLBO oo... ee +18V MAX64, C$ 1.0, ..0C to+70C Input Voltage, LBI, LBO, VFB, COMP. 0 3V to (+VOUT + 0.3V) MAX64 _E . . 40C to 85C LX Output Current 200.0000. 000.0202. ..,. 450mA Peak MAX64_ _M -65C to 125C LBO Output Current .... . cee ..50mMA Storage Temperature ............... . -65'C to +160 C Power Dissipation Lead Temperature (Soldering. 10 sec.) +300C Plastic DIP (derate 8 38mW/"C above +50C) . 625mWw Small Outline (derate 6mMW/"C above +50C) ..... 450mWw CERDIP (derate 8mW/'C above +50C) ........... 800mW 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 (Ta = +25 C, unless otherwise noted.) fe _ PARAMETER | symeot |_ CONDITIONS MIN TYP MAX UNITS Voltage at VOUT | | Operating Voltage J +VS | Over Temperature | 2.0 16.5 Vv | Voltage at VOUT | Start-up Voltage Ta =+25C 15 1.3 Vv | Over Temperature 1.8 | LX Off, Over Temperature | Supply Current da Vout = My : OB 30 | mA | | _ | VOUT = +15V_ 0.75 2.5 _ __ ee + = +25C 1.24 1.31 1.38 | Reference Voltage (Internal) | vA VREF ws Temperature 190 440 Vv | No Load, VFB = GND, | | | Over Temperature | MAX641A | 475 5.0 5.25 | 5% Output VOUT Voltage (Note 1) | | vata \ Accuracy au 3 1p 8 ns | Vv | MAX641B | 4.5 5.0 5.5 | | MAX642B \ som Output 10.8 12.0 13.2 ___MAX6438 ecuracy 13.5 15.0 16.5 F eticinoy a With External MOSFET 80 | % | wey : Line Regulation (N (Note 1) : | O.5VOUT < +5 < VOUT | 0.08 % VOUT | | +Vs = 0.5VOUT, Load Regulation (Note 1) Pout = OmW to 150mW 0.2 % VOUT 2 MAXKIsvIFixed Output 10W CMOS Step-Up Switching Regulators ELECTRICAL CHARACTERISTICS (continued) (Ta = +25C. unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS VOUT = +5V MAX641A 40 45 50 MAX641B 37.5 45 56.5 VOUT = +12V Oscillator Frequency fo MAX642A 45.5 50 56 kHz MAX642B 42 50 62.5 VOUT = +15V MAX643A 45.5 50 56 MAX643B 42 50 62.5 Oscillator Frequency Tempco -60 Hz2/Cc MAX641, VOUT = +5V 40 50 60 Oscillator Duty Cycle MAX642, VOUT = +12V 40 50 60 % MAX643, VOUT = +15V 40 50 60 VOUT = +5V, IOUT = +10mA 140 EXT Output Resistance VOUT = +15V. IOUT = +30mA 90 Q. CL = 3300F EXT Switching Time ton. tOFF VOUT = +5V 160 ns VOUT = +15V 125 : Ix = 100mA. VOUT = +5V 6 12 LX On Resistance RON VOUT = +15V 35 7 QQ V4 = +16.5V TA = +25C 0.01 1.0 LX Leakage Current IXL Over Temperature (C.E) 30 LA Over Temperature (M) 100 Diode Forward Voltage VF Ip = 100mA 1.0 Vv VFB Input Bias Current IFB 0.01 10 nA Low Battery Threshold VLBI 1.31 Vv Low Battery Input Bias Current ILI 0.01 i0 na V2=40.4V.V1=411V Low Battery Output Current ILBO Ta = 425C 1.0 mA Over Temperature 0.5 Low Battery Output _ _ Leakage Current | ILBOL V2 = +16.5V, V1 = +1.4V 0.01 3.0 uA Note 1: Guaranteed by correlation with DC pulse measurements. MAAXAI/VI v9/Ev9/LV9OXVNMAX64 1/64 2/643 Fixed Output 10W CMOS Step-up Switching Regulators Pin Description ee ee ~pe ~~ Ls PIN | NAME FUNCTION PIN | NAME FUNCTION | [C 1 : LBI | Low Battery Input. When the voltage at LBI | | 6 | EXT | The drive output for an external power | is lower than the Low Battery Detector thresh- | MOSFET or bipolar transistor EXT swings | old (+1.31V), LBO sinks current. | | from GND to VOUT and has approximately SS aa ee + 100Q sink/source impedance. EXT is low | | hen L i A x 2 LBO | The Low Battery Detector Output is an open | when LX is open circuit and high when L | drain N-channel MOSFET which sinks cur. || | ison | rent when the LBI is below +1.31V. | i ~~ STO |. ja 7 | VEB_ | When VFB is grounded, the DC-DC con- verter output will be the factory preset value 3 | GND Ground Ke | | | | When an external voltage divider is con- | ted to VFB, this pin becomes the feed- 4 | x In low-power applications, LX drives the ex- | | | nec | | | ternal inductor with an internal N-channel | _ back input for adjustable Output operation. power MOSFET. LX has a typical output re- . . | sistance of 6Q and a peak current rating of | | 8 | COMP | The Compensation input is connected to the | 450MA | | internal voltage divider which sets the fixed a | voltage output. In some circuit board lay- outs. alead compensation capacitor (100pF | 5 VOUT | The regulated DC-DC converter output when |_| | to 10nF) connected belween VOUT and | the internal MOSFET and catch diode are COMP reduces low-frequency ripple and im- used. When an external diode is used. this | | | | | proves transient response. Ground comp | pin becomes the supply voltage input pin when using an External Voltage divider on and is usually connected to the cathode of | | | VEB | the external diode. | | | | : Le a _ _ _ Typical Operating Characteristics SUPPLY CURRENT Ly OUTPUT CURRENT OSCILLATOR FREQUENCY vs. OUTPUT VOLTAGE vs. VOUT vs. OUTPUT VOLTAGE 20 400 Th 725C Ta +25C Vout = 15 Your = 10 15 = 300 N. th our _ Vour = 5V Es 10 5 200 i Lo ~ e Lx SWITCHING 3 Your = 3 a5 f-_ = 198 | 4 | Vout = 2v I ; Ly OFF , | iz = 25C 0 5 10 15 0 05 10 1b 20) 2b 8 0 2 4 6 B WM 2 4 16 Vour (M4 tx VOLTAGE (] Your () IWA AISI | | | | | | | | | | | |Fixed Output 10W CMOS Step-Up Switching Regulators Detailed Description Basic Operation The operation of the MAX641 series can best be under- stood by examining the regulating loop of Figure 1. When the output voltage drops below the preset (or externally set) value, the Error Comparator switches high ana con- nects the internal 45kHz Oscillator to the gate of the internal MOSFET and ta the EXT output. EXT is typically connected to the gate of an external N-channel power MOSFET. When EXT is activated, the MOSFET turns on and off at the internal clock frequency. When EXT is high, the MOSFET switches on, and the inductor current increases linearly storing energy in the coil. When EXT switches the MOSFET off, the coils magnetic field collapses, and the voltage across the inductor reverses sign. The voltage at the anode of the catch diode then rises until the diode is forward biased, delivering power to the output. As the output voltage reaches the desired level, the Error Comparator inhibits EXT until the load discharges the output filter capacitor to less than the desired output level. Though designed to power an external MOSFET or bipo- lar transistor, the MAX641 series will also work well in low- power applications (<250mW) with Its own internal MOSFET and catch diode. In these applications, the LX output does the current switching and an externa! capac- itor and inductor are all that are needed Vin, Bootstrapped Operation The MAX641/642/643 do not have a VIN pin. Input power to start the DC-DC converter is supplied via the external inductor (and diode, if used) to the VOUT pin, Once the converter has started, it is then powered from its own output. This design ensures that the outout MOSFET will nave maximum gate drive and, hence, a minimum Ron. It also allows the converter to start at lower input voltages. Vin Greater Than VOUT If the regulators input voltage is more than 1 forward diode drop greater than the desired output voltage, the EXT and LX outputs will not turn on, and the output will no longer be regulated. However, current will be sup- plied to the load directly through the catch diode. As long as the input is more than 0.6V above the desired output. | Wwe vn a ee _ . {Our sv | | wy 7 aru T 1N5817 | he | at | | | LOW BATTERY a | | | | OUPUT so te | | ow ex seRy PO ext [LX po | gee of [op || ee ee ee | | 100k rt a L | ] L dis | | Le je | | ft | ERROR ;? + | | > 4) oWewareR re + | | ove | __TSIVREF rN, Lair | | |e ; [Ko | seen cour La | | ps ae | an f f ios = eno 3 | PS de ny | Lf = ost L | | r COMPARATOR | | | | Sx somy FOR VOUT = +5V | | | = ON MAX641 | | | Figure 1. +3V to +5V Converter and Block Diagram for MAX64 1/642/643 MAXAIL/VI a 5 v9/Er9/1V9XVNMAX64 1/642/643 Fixed Output 10W CMOS Step-up Switching Regulators the output will equal the input voltage, less the forward drop of the catch diode. Fixed or Adjustable Output For operation at one of the preset output voltages (+5V for the MAX641, +12V for MAX642, and +15V for MAX643), VFB is connected to GND, and no external resistors are required. For other output voltages, a voltage divider is connected to VFB as shown in Figure 2. The output is set by R3 and R4 as follows: Let R4 be any resistance in the 10kQ to 10MQ range, typically 100kQ, then: VOUT | R3 = R4 (F 33 Low Battery Detector The Low Battery Detector compares the voltage on the Low Battery Input (LBI), with the internal + 1.31V bandgap reference. The Low Battery Detector Output (LBO) goes low whenever the input voltage at LBl is less than +1.31V. The Low Battery threshold is set by resistors R1 and R2 (Figure 1) 1) Let R2 be any resistance in the 10kQ to 10MQ range, typically 100kQ. VLB RY= Re Cary 7? What Value Of Inductor? A General Discussion The converters in this data sheet operate by charging an inductor from a DC input, then discharging the inductor to generate a DC output greater than the input. (VLB is the desired Low Battery detection voltage) The proper inductor for any DC-DC converter depends on three things: the desired output power, the input voltage (or range of input voltage), and the converters oscillator frequency and duty cycle. The oscillator timing is important because it determines how long the coil will be charged during each cycle. This, along with the input voltage, determines how much energy will be stored in the coil. The inductor must meet four electrical criteria: | ] Value- Low enough inductance so it stores ade- quate energy at the worst-case, low input voltage. High enough so excessive and potentially destructive currents are avoided under worst-case high conditions for power-switch transistor on time and high input voltage. pV. @ _ Vin IN517 tr VOUT Vin 6 EXT LX 3 VOUT VOUT | --@- ~ AAAXLAA 2 | . MAX641 R3 => 100nF oe MAX642 , 4 | [ MAX643 v8 : R4 < GND ee IL Figure 2. Connections for Adjustable Output Operation [] Saturation- The coil must deliver the correct induc- tance value at the worst-case, high peak operating cur- rent. [] EMI- Electromagnetic interference must not upset nearby circuitry or the regulator IC. Ferrite bobbin types work well for most digital circuits; toroids or pot cores work well for EMl-sensitive analog circuits. [ ] DC resistance- Winding resistance must be ade- quately low so efficiency is not affected and self-heating does not occur. Values less than 0.52 are usually more than adequate. Other inductor parameters, such as core loss or self-res- onant frequency, are not a factor at the relatively low MAX641/642/643 operating frequency. Inductor Value- Low Enough? The problem that bites designs most often, especially in the production or pre-production phase, happens when the inductor value is too high. These units fail to deliver enough load current and exhibit poor load regulation. The worst case |s: {] Maximum load current [] Minimum supply voltage [] Maximum inductor value, including tolerance [] Maximum on resistance of the switch because it reduces the excitation voltage across the inductor [ ] Worst-case low on time MAKISVIFixed Output 10W CMOS Step-Up Switching Regulators Inductor Value- High Enough? The inductor value must be high enough so peak currents do not stress the transistor or cause the inductor core to saturate. Odd symptoms can be traced to excessive inductor currents: low efficiency, rattling heat sinks, whining coils, and increased output ripple. Very low inductor values may result in damaged power transistors. The slope of the inductor current, and therefore the peak value that it reaches in a given on time, is determined by the supply voltage and the inductor value. The worst case OCCUrS at: [] Maximum supply voltage [] Minimum inductor value, including tolerance [|] Minimum on resistance of the switch [] Low switching frequency (or maximum switch on time) Inductor Selection The inductor equations below must be calculated for both worst-case sets of conditions. The final value chosen should be between the minimum value and maximum value calculated. Within these bounds, the value can be adjusted slightly lower for extra load capability or higher for lowest ripple. VOUT +VpIODE VIN (0.25) (VIN -Vsw) Vin -V , Vin=Vsw lok Where Vsy is the voltage drop across the switch in the on state. Conservatively, the worst case is about 0.75V max, 0.25V min with Vin = +15V and 1.5V max, 0.5V min with VIN = +5V. Example: A +5V 10% input must be converted to +15V at 15mA. A Schottky diode (1N5817) and a MAX643B are used. Calculate maximum inductor value allowed: io, - 15V +0.4V-4.5V P& = (9.25) (4 5V 0.75V) _ 45-075 ~ 174mA Calculate the minimum inductor value allowed: [1] Ipk = (IOUT) (2] (ton) (15mA) = 174mA (8us) = 172WH Ipk = 450mA (from table of max ratings, use the power MOSFET max ratings for external transistor circuits) _ 5.5V-0.25V L= A50mA (12us) = 140uH MAAAILWVI A value of 160uH would be a good choice for this application. The "A" grade devices, with tighter oscillator tolerance, allow more output current in a given applica- tion. Application Hints External MOSFET An external MOSFET or transistor can be used to drive the inductor in high-power applications. The current handling specifications of the device must match the peak current which flows in the inductor (see Inductor Selection). The only restriction on the size of the external driver is that the EXT output must be able to drive the external device's gate (or base) capacitance at the inter- nal clock rate (45kHz). An external driver may be used to increase operating voltage range of the MAX641/642/643. Table 2 contains a list of MOSFETs and their manufactur- ers. Logic level MOSFETs should be used when the supply voltage is less than +5V. Refer to Figures 4 and 5 for circuits requiring external MOSFETs. Output Filter Capacitor The MAX641/642/643 output ripple has 2 components which are 90 out of phase. One component results from the change in the stored charge on the filter capacitor with each LX pulse. The other is the product of the capacitors charge-discharge current and its Equivalent Series Resistance (ESR). With low-cost aluminum elec- trolytic capacitors, the ESR produced ripple is often larger than that caused by the change in charge. Con- sequently, high-quality aluminum or tantalum filter capac- itors will minimize output ripple, even if smaller capacitance values are used. Best results at a reason- able cost are typically achieved with a high-quality alu- minum electrolytic, in the 100uF to S0QuF range, in parallel with a 0.1uF ceramic capacitor. Diodes When the MAX641/642/643 are used with an external power MOSFET, the internal diode can be used if the peak diode current rating (450mA) and maximum pack- age power dissipation ratings are observed. For higher power circuits, an external Schottky diode such as the 1N5817 (1 Amp) or 1N5821 (3 Amp) should be con- nected between LX and VOUT in parallel with the internal diode. Although 1N4001s and other general purpose rectifiers are rated for high currents, they are not recom- mended because their slow turn-on time results in exces- sive losses and poor efficiency. v9/ErV9/4V9OXVNMAX641/642/643 Fixed Output 10W CMOS Step-up Switching Regulators Bypassing and Compensation pulses to occur in bursts. This problem can often be avoided by minimizing pin lengths and circuit board trace size at the VFB node. Normal operation with evenly distributed pulses can also be restored by adding alead" compensation capacitor (100pF to 10nF) in parallel with Since the inductor charging current can be relatively large, high currents flow through the ground connection near the MAX641/642/643. To prevent unwanted feed- back, the impedance of the ground path must be as low as possible, and a bypass capacitor (10uF) should be at RS. the VOUT pin, even if large filter capacitor are used The COMP input allows access to the internal voltage elsewhere in the circuit. divider so that compensation can also be added when fixed output operation is used. A capacitor connected between VOUT and COMP adds a lead" to the regulator's response. When large values (>50kQ) are used for the voltage setting resistors (R3 and R4 of Figure 2), stray capaci- tance at the VFB input can add a "lag" to the feedback response, destabilizing the regulator and causing output Table 1. Representative N-Channel Power MOSFETs NUMBER PKG. (los Ves = X) MMAX) MFG. IRFD121 Ap DIP 0.3Q (1.3A, 10V) 60 H/IR | BUZ71A TO-220 0.120 (BA, 10V) 50 MOT/SI/SM BUZ21 TO-220 0.12 (9A, 10V) 100 MOT/S/SM IRF513 TO-220 0.8 (2A, 10V) 100 H/IR/MOT/SI | IRF530 TO-220 0.18 (8A, 10V) 100 H/IR/MOT/SI IRF540 TO-220 0.0850 (8A. 10V) 100 H/IR/MOT/SI IRF620 TO-220 0.8Q (2.5A, 10V) 200 H/IR/MOT/SI | IRF640 TO-220 0.180.(10A, 10V) 200 H/IR/MOTISI | Manufacturer Code: H= Harris. IR= International Rectifier, MOT= Motorola, SM= Siemens, Sl= Siliconix N-Channel Logic-Level Power MOSFETs Rien Px: tor Vas wma nr RFP25NO6L TO-220 0.859 (12.5A, 5V) 50 H RFP12N10L TO-220 0.20 (6A, 5V) 100 H | _PFPISNO6L TO-220 ; 0.149(7.5A, 5V) 50 oH IRL540 TO-220AB 0.112 (24A, 4V) 100 IR IRL734 TO-220AB 0.3Q (7.8A, 4V) 60 IR IRZ14__ TO-220AB_ 0.078 (23A, 4V) ; 60 IR | MTM25NO05L TO-220AB 0.19 (12.5A, 5V) 50 MOT MTM15NOSL TO-220AB 0.15 (7.5A, 5V) 50 MOT MTP 12N10L TO-220AB 0.18Q (6A, 5V) 100 MOT | Manufacturer Code: H= Harris, IR= {nternational Rectifier. MOT= Motorola Note: This list does not constitute an endorsement by Maxim Integrated Products and is not intended to be a comprehensive list of all manufacturers of these components 8 MAXILVIFixed Output 10W CMOS Step-Up Switching Regulators Table 2. Inductance Values for Commonly Encountered Power Supplies (Figure 5) MAXIM Vin VOUT lour TYP EFF lok . INDUCTOR (L) PART NO. (V) (VY) (mA) (%) (A) PART NO. uH Q 3 5 200 83 13 6860-13 100 10 maxeai BB 8008 2.0 6860-09 AH 5 12 200 91 12 6860-08 39 0.05 MAX642 5 12 350 39 2 6860-04 18 0.08 5 2 8 BF 8B 700-02 12 0.01 5 15 100 92 1.2 6860-08 39 0.05 5 15 150 89 15 6860-06 27 0.04 MAX643 5 15 225 89 2 6860-04 18 0.03 5 15 325 85 35 7200-02 12 001 L * Ferrite Bobbin Coils from Caddell-Burns, NY (516) 746-2310 Inductor Saturation It is important to be sure that the inductor does not saturate, particularly in high-power circuits. Inductor saturation leads to very high current levels through the external boost transistor, causing excessive power dissi- pation, poor efficiency, and possible damage to the inductor and the external transistor Test for saturation by applying the maximum load and the maximum input voltage while monitoring the inductor current with a current probe. The normal inductor current waveform is a sawtooth with a linear current ramp. Sat- uration creates a nonlinear current waveform with a very rapid increase in current once the inductor saturates. To ensure that the current rating(s) of the FET(s) is not exceeded, the inductance value of the coil, including the manufacturer's tolerances, should never be lower than that used in the calculations or in Table 2, In addition, to ensure that the core does not saturate, the current rating of the coil should be greater than the peak current, Ipk. Coil resistance has a significant effect on the output current. To increase the output current and raise the overall efficiency, the inductor should have a resistance less than a few tenths of an Ohm. Inductance Values Inductance values for commonly encountered power supplies are listed in Table 2. The data in Table 2 refers to the circuit in Figure 5. Typical Applications Basic High-Power Hookup Figure 5 shows the standard circuit configuration for a fixed outout step-up DC-DC converter. The output power is determined by the current ratings of the external MOSFET and inductor, as well as, the switching time of the EXT output into the gate capacitance of the MOSFET MAAK Typical switching times are given in the Electrical Char- acteristics Table. Low-Power Step-Up Conversion In low-power applications, the LX output and internal diode may be used instead of an external MOSFET and diode, as shown in Figure 3. The power handling capa- bility of this circuit is about 250mW. See the MAX631 data sheet for inductor selection information High-Voltage Operation If the external MOSFET or transistor has an adequate voltage rating, the output voltage range of the MAX641/642/643 can be extended (Figure 4). The ad- justable output mode must be used (VFB connected to external resistors), and the VOUT pin must be connected to the circuit's INPUT voltage. FO | | VOUT Vin | 200-500uF VOUT - SV WITH MAX641 | ~ VOUT - +12V WITH MAX642 | VIN [4 VOUT +15V WITH MAX643 | Lx 5 VOUT | VOUT} @ - > ~100RF .-)-, 100,uF | 8 | | ANAXLAA COMP | | MAX641 7 | MAX642 VBE MAX643 3 | GND J 4 | l | Figure 3. Low-Power. Fixed Output Step-Up Converter Using LX 9 v9/Zv9/LVOXVINMAX64 1/642/643 Fixed Output 10W CMOS Step-up Switching Regulators 10 100uH 1N4935 VOUT -50V oy 220uF wT +12V a | | In 4 NC | ois | 5 EXT LX 4vout +L rou ANAXIAA - MAX641 VFB MAX642 MAX643 COMP GND 4 1 | | tT {MQSS = 1000pF RST 7 __ + i > om Sgn WOT, R4 > 13 1 po | VIN | v | | ze C | Sy | | maxim xt fhe MAX641 rT | | MAX642 = | MAX643 vouT 5 | 8 COMP - 1-0 ' | LBI GND EB 1000pF | | L_ Figure 5. High Output Current Step-Up Converter (See Table 2) MIA XAITSVIFixed Output 10W CMOS Step-Up Switching Regulators Table 3. Maxim DC-DC Converters NUMBER DESCRIPTION VOLTAGE VOLTAGE COMMENTS | Low-Power Boost Converters | MAX630/4193 DC-DC Boost Converter 2V to 16.5V VOUT>VIN Improved RC4193 2nd source MAX631 DC-DC Boost Converter 1.5V to 5.6V +5V Only 2 external components | MAX632 DC-DC Boost Converter 1.5V to 12.6V +12V Only 2 external components MAX633. = _szDC-DC Boost Converter ASV t015.6V + 15V__ Only 2 external components | High-Power Boost Converters MAX641 High-Power Boost Converter 1.5V to 5.6V +5V Drives external MOSFET | MAX642 High-Power Boost Converter 1.5V to 12.6V +12V Drives external MOSFET MAX643 _ High-Power BoostConverter ss T.SV 1015 6vV. + 15V__ Drives external MOSFET | Low-Voltage Boost t Converters ee a __ | MAX654 Low-Voltage Boost Converter 1.15V to 5.6V +5V Optimized for 1 cell MAX655 Low-Voltage Boost Converter 1.5V to 5.6V +5V Optimized for 2 cells | MAX656 Low-Voltage Boost Converter 1.15V to 5.6V +5V Drives external MOSFET MAX657 Low-Voltage Boost Converter 1.15V to 3.6V +3V Optimized for 1 cell MAX658 Low-Voltage Boost Converter 1.5V to 5.6V +5V Drives external MOSFET | MAX659 ____ Low-Voltage Boost Converter 1.5V to 3.6V__ +3V Optimized for 2 cells Invertering Converters | MAX634/4391 DC-DC Voltage Inverter 2V to 16.5V up to-20V. Improved RC4391 2nd source | MAX635 DC-DC Voltage Inverter 2V to 16.5V -5V Only 3 external components MAX636 DC-DC Voltage Inverter 2V to 16.5V -12V Only 3 external components MAX637 _ DC-DC Voltagelnverter AV TOTO SV -15V Only 3 external components | Step-Down Converter | | MAX638 DC-DC Voltage Steodown 3V to 16.5V VOUT< VIN Only 3 external components . Charge-Pump Converters | MAX680 + Output Charge Pump 2V to BV +2VIN 4 external capacitors MAX681 + Output Charge Pump 2V to6Vv t2VIN MAX680 with internal capacitors | ICL7660 Negative Charge Pump 1.5V to 10V -VIN Not regulated | ICL7662/Si7661 _ Negative Charge Pump _ 4.5Vto20v. VIN: __Not regulated | _ Dual Output Converters _ ee _ _ / MAX742 Current-Mode Controller +5V +15V/+12V Drives external MOSFETs | ; MAX743 _ Current-Mode Regulator __ +5V00 #15V/E12V BW output _ 1 SVIAKIVI v9/Cv9/LVOXVINMAX641/642/643 Fixed Output 10W CMOS Step-up Switching Regulators Chip Topography _ Ordering Information (continued) GND GND 180m | _PART* __sSTEMP.RANGE _ PIN-PACKAGE | ; ot | | MAX643XCPA_ OC to +70C 8 Plastic DIP fp mn MAX643XCSA OC to +70 C 8 Narrow SO ies MAXBASKCIDOGio 706 bee | | | Hi an ms _MAX643XEPA_ 40C to +85C 8 Plastic DIP ih 1 MAX643XESA_ 40. C to +85'C 8 Narrow SO ne Wooley ae _MAX643XEJA_ 40C 10 +85 = B CERDIP |_MAX643xXMJA 55C to +125C _8 CERDIP Lx *X = A for 5% Output Accuracy, X = B for 10% Output Accuracy Vout XT Veg COMP 0.096 | | {2.44mm) Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit Patent licenses are impliod Maxim reserves the right to change the circuitry and specifications without notice at any time 12 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7609 1990 Maxim Integrated Products. Printed USA 3/90 MAXI iS a registered trademark of Maxim Integrated Products Dual Mode is a trademark of Maxim Integrated Products