MAXIM MAX1640/MAX1641 Manual
Contents
1. TE resets the internal PWM latch shutting off the external P channel FET 9 GND Ground 10 CS Negative Current Sense Comparator Input 11 CS Positive Current Sense Comparator Input 12 PGND High Current Ground Return for the Output Drivers 13 NDRV Gate Drive for an Optional N Channel FET Synchronous Rectifier 14 PDRV Gate Drive for the P Channel FET 15 LDOH Internal Input Referenced Low Dropout Linear Regulator Output Bypass with a 0 33yuF capacitor to IN 16 IN Power Supply Input Input of the internal low dropout linear regulators MAAIAA o S 55 TV9OTXVW OV9OTXVIN MAX1640 MAX1641 Adjustable Output Switch Mode Current Source with Synchronous Rectifier MODE CONTROL i i i i i i i i r NDAV i i L p np MAXIM MAX1640 MAX1641 Figure 1 MAX1640 MAX1641 Functional Diagram 6 MAXIM Adjustable Output Switch Mode Current Source with Synchronous Rectifier 1 2 1R7309 PDRV MAXIM MAX1641 Figure 2a Standard Application Circuit Detailed Description The MAX1640 MAX1641 switch mode current sources utilize a hysteretic current mode step down pulse width modulation PWM topology with constant off time Internal comparators control the switching mechanism These comparators monitor the current through a sense resistor RSENSE and the voltage at TERM When2. 1 470 1 460 2 4 6 8 10 12 14 16 18 20 22 24 OUTPUT VOLTAGE V MAX1641 OUTPUT CURRENT vs INPUT VOLTAGE 4 8 12 16 20 24 28 INPUT VOLTAGE V OFF M ODE SUPPLY CURRENT NO LOAD MAX1640 41 TOOO7 4 8 12 16 20 24 28 INPUT VOLTAGE V MAX1640 OUTPUT CURRENT vs INPUT VOLTAGE 4 8 12 16 20 24 28 INPUT VOLTAGE V MAX1641 Maxie40 41 TOO02 OUTPUT CURRENT vs OUTPUT VOLTAGE MAX1640 41 TOO0S 2 4 6 8 10 12 14 16 18 20 22 24 Vour V SWITCHING FREQUENCY vs RToFF MAX1640 41 TOC 08 0 50 100 150 200 250 300 350 400 Torr KQ QUIESCENT QURRENT mA OUTPUT CURENT A 1 510 1 500 1 490 1 480 1 470 1 460 1 450 VLoan 3V MAX1640 OUTPUT CURRENT vs OUTPUT VOLTAGE Ta 40 C 3 i Ta 85 C a Tax 425 C 2 4 6 8 10 12 14 16 18 20 22 24 OUTPUT VOLTAGE V QUIESCENT CURRENT vs INPUT VOLTAGE NO LOAD MAX1640 41 TO006 4 8 12 16 20 24 28 INPUT VOLTAGE V LINE TRANSIENT RESPONSE 2ms div A OUTPUT CURRENT D1 D0 1 1A div B INPUT VOLTAGE 10V div MAALM Max1640 41
3. 70 C QSOP derate 8 30mMW C above 70 0 sses 667mW Operating Temperature Range MAX164 FEE nriran ieee t 40 C to 85 C Storage Temperature Range e eee 65 C to 150 C Lead Temperature soldering 10sec cee 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 VIN 12V VouT 6V Circuit of Figure 2 Ta 0 C to 85 C unless otherwise noted Typical values are at Ta 25 C PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Voltage Range VIN 5 5 26 V Linear Regulator Output 7 VIN VIN VIN Voltage Vin Referenced VLDOH MIN 5 5V to 26V ILoap 0 to 20mA 55 50 45 y Linear Regulator Output 7 Voltage Ground Referenced VLDOL Vin 5 5V to 26V ILOAD 0 to 20mMA 4 5 5 0 5 5 V Full Scale Current Sense MAX1640 142 150 158 mV Threshold MAX1641 147 150 153 Quarter Scale Current Sense MAX1640 36 42 48 ay Threshold MAX1641 34 37 5 41 Current Sense Line Regulation Vin VourT 0 5V to 26V 0 03 A N MAX1640 0 1 0 4 Output Current Compliance
4. IRC LR2010 01 series AVX TPS series PAPA Sprague 595D series MBAR5340t3 Rectifier Motoroia IN5817 IN5822 Nihon NSQ03A04 turns off The synchronous rectifier remains off for 90 of the off time In low cost designs the synchronous rectifier FET may be replaced by a Schottky diode Component Selection External Switching Transistors The MAX1640 MAX1641 drive an enhancement mode P channel MOSFET and a synchronous rectifier N channel MOSFET Table 2 When selecting a P channel FET some important para meters to consider are on resistance rDS ON maxi mum drain to source voltage VDS max maximum gate to source voltage Vas max and minimum threshold voltage VTH min In high current applications MOSFET package power dissipation often becomes a dominant design factor I2R power losses are the greatest heat contributor for both high side and low side MOSFETs Switching loss es affect the upper MOSFET only P channel since the Schottky rectifier or the N FET body diode clamps the switching node before the synchronous rectifier turns on Rectifier Diode If an N channel MOSFET synchronous rectifier is not used a Schottky rectifier is needed The MAX1640 9 TV9OTXVW OV9OTXVIN MAX1640 MAX1641 Adjustable Output Switch Mode Current Source with Synchronous Rectifier PDRV MAXUM MAX1640 LOW SIDE IS SHORTED Figure 5 Microcontroller Battery Charger MAX1641
5. TOC 09 0A ov Adjustable Output Switch Mode Current Source with Synchronous Rectifier Typical Operating Characteristics continued Circuit of Figure 2 Ta 25 C unless otherwise noted CURRENT MODE CHANGE RESPONSE TIME EXITING OFF MODE MAX1640 41 TOC11 ov 2ms div 20us div Vin 12V Vser 1V RLoap 42 NO OUTPUT CAPACITOR Vin 12V Rloap 4Q A OUTPUT CURRENT DO D1 0 1A div A D0 D1 1 2V div B LOAD VOLTAGE AC coupled 500mV div B OUTPUT CURRENT 0 5A div Pin Description PIN NAME FUNCTION Internal Ground Referenced Low Dropout Linear Regulator Output l oc Bypass with a 0 1uF capacitor in parallel with a 4 7uF capacitor to GND Off Time Select Input A resistor RTOFF connected from this pin to GND programs the off time for the hys 2 TOFF teretic PWM step down converter This resistor also sets the period in duty cycle mode See Duty Cycle Mode and Programming the Off Time 3 4 D1 DO Digital Inputs Select mode of operation Table 1 5 CC Constant Current Loop Compensation Input Bypass with a 0 01uF capacitor to GND 6 REF Reference Voltage Output VREF 2V Bypass with a 0 1uF capacitor to GND 7 SET Current Select Input Program the desired current level by applying a voltage at SET between OV and VREF l Vset 13 3RsENSE See Figure 3 Maximum Output Voltage Termination Input When Vrerm exceeds the reference voltage the comparator
6. VouT 2V to 24V A N MAX1641 0 1 DO or D1 high 2 4 mA Quiescent Vin Supply Current DO D1 low off mode 500 pA Output Current in Off Mode DO D1 low 1 yA VLDOL Undervoltage Lockout 4 05 4 20 4 35 V Reference Voltage VREF 1 96 2 00 2 04 V Reference Load Regulation IREF 0 to 50A 4 10 mV Vset Input Current 1 yA FET Drive Output Resistance PFET and NFET drive 12 Q Off Time Range 1 10 us Off Time Accuracy RTOFF 62kQ 1 7 2 2 2 7 us Pulse Trickle Mode Duty Cycle DO low D1 high RToFF 100k 27 33 40 ms Period Neca ichle Mode Duly seyele DO low D1 high RTOFF 100k 12 5 Note 1 This ratio is generated by a 1 8 clock divider and is not an error source for current calculations 2 MAXIM Adjustable Output Switch Mode Current Source with Synchronous Rectifier ELECTRICAL CHARACTERISTICS continued VIN 12V VouT 6V Circuit of Figure 2 Ta 0 C to 85 C unless otherwise noted Typical values are at Ta 25 C PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS PWM Maximum Duty Cycle 100 Input Low Voltage VIL DO D1 0 8 V Input High Voltage VIH DO D1 2 4 V Input Leakage Current liN DO D1 1 uA ELECTRICAL CHARACTERISTICS VIN 12V VouT 6V Circuit of Figure 2 Ta 40 C to 85 C unless otherwise noted PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Vol
7. 0 1 55 s o0o20 0070 0 05 018 CA E72 ee na D 337_ 344 856 8 74 20 AB w C 0075 0098 019 ne S 0500 0550 127 140 b j H fD SEE VARIATIONS Boe e 28L ee p 337_ 344 856 874 Jealac e 025 BSC 0 635 BSC 0250 0300 064 076 H 230 244 5 84 6 20 S Y Nn 010 016 025 0 41 D 386 393 980 998 28 AD L 0t6 035 041 0 89 s o250 0300 064 0 76 SEE VARIATIONS S SEE VARIATIONS o 8 0 8 j D SES NOTES D amp E DO NOT INCLUDE MOLD FLASH R PROTRUSIONS SVIAAI VI e LD FLASH OR PROTRUSIONS NOT T PREPRI TARY ee EXCEED 006 PACKAGE DUTLINE QSOP 150 INCH 025 LEAD PITCH 3 C NTR LLING DIME SI NS NCHES APPROVAL DOCUMENT CONTROL NO REV Ly 21 0055 A l 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 Maxim Integrated Products 120 San Gabriel Drive Sunnyvale CA 94086 408 737 7600 11 2002 Maxim Integrated Products Printed USA MAXIM is a registered trademark of Maxim Integrat
8. 19 1245 Rev 1 1 02 General Description The MAX1640 MAX1641 CMOS adjustable output switch mode current sources operate from a 5 5V to 26V input and are ideal for microprocessor controlled battery chargers Charging current maximum output voltage and pulse trickle charge are programmed with external resistors Programming the off time modifies the switching frequency suppressing undesirable har monics in noise sensitive circuits The MAX1640 s high side current sensing allows the load to connect directly to ground eliminating ground potential errors The MAX1641 incorporates a low side current sense The MAX1640 MAX1641 step down pulse width modu lation PWM controllers use an external P channel MOSFET switch and an optional external N channel MOSFET synchronous rectifier for increased efficiency An internal low dropout linear regulator provides power for the internal reference and circuitry as well as the gate drive for the N channel synchronous rectifier The MAX1640 MAX1641 are available in space saving 16 pin narrow QSOP packages Applications Battery Powered Equipment Laptop Notebook and Palmtop Computers Handy Terminals Portable Consumer Products Cordless Phones Cellular Phones PCS Phones Backup Battery Charger Pin Configuration TOP VIEW LDOL MAKINI MMA AKIM Adjustable Output Switch Mode Current Sources with Synchronous Rectifier Features 95 Efficiency 5 5V to 2
9. 6V Input Supply Range 2V to 24V Adjustable Output Voltage Range 100 Maximum Duty Cycle Low Dropout Up to 500kHz PWM Operation Optional Synchronous Rectifier 16 Pin QSOP Package Current Sense Accuracy 2 MAX1641 5 3 MAX1640 gt gt o o o o Ordering Information TEMP RANGE 0 C to 70 C PART MAX1640C D MAX1640EEE 40 C to 85 C MAX1641C D 0 C to 70 C PIN PACKAGE Dice 16 QSOP Dice MAX1641EEE 40 C to 85 C 16 QSOP Dice are specified at Ta 25 C DC parameters only Typical Operating Circuit Vin 5 5V TO 26V MAXIM MAX1640 CC TERM GND LDOL Maxim Integrated Products 1 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 LVOLXVIN OVOLXVIN MAX1640 MAX1641 Adjustable Output Switch Mode Current Source with Synchronous Rectifier ABSOLUTE MAXIMUM RATINGS URINE Dh ole tee Feat icone ab hd corrects 0 3V to 28V LDOH to IN 0 3V to 6V EDOM to GN Dr ena are rede inn 0 3V to 6V PDRV to GND u ceeecsseeessssetessssseeees VLDOH 0 3V to Vin 0 3V NIDIA CKCIN DEAN 0 3V to VLDOL 0 3V TOFF REF SET TERM CC to GND 0 3V to VLDOL 0 3V DIODA CECIN ID asain Gee a ete aan 0 3V to 6V CSE CSO GND sie att rO ara 0 3V to 28V AENIBH CECIN D EEE EATEN 0 3V Continuous Power Dissipation Ta
10. ed Products TV9OTXVW OV9OTXVIN
11. igher than the output battery voltage ILOAD x RLOAD An external resistor divider between the output and ground Figure 4 sets the voltage at TERM Once the voltage at TERM exceeds the reference the internal comparator turns off the P channel FET terminating current flow Select R4 in the 10kQ to 500kQ range R3 is given by R3 R4 VouT VTERM 1 MAXIM Adjustable Output Switch Mode Current Source with Synchronous Rectifier where VTERM 2V and VouT is the desired output voltage Programming the Off Time When programming the off time consider such factors as maximum inductor current ripple maximum output voltage inductor value and inductor current rating The output current ripple is less than the inductor current rip ple and depends heavily on the output capacitor s size Perform the following steps to program the off time 1 Select the maximum output current ripple IR A 2 Select the maximum output voltage VouT MAX V 3 Calculate the inductor value range as follows LMIN VOUTMAX X 1Hs IR LMAX VOUTMAX X 10us IR 4 Select an inductor value in this range 5 Calculate torr as follows Lx torr VOUTMAX 6 Program torr by selecting RTOFF from RTOFF 29 3 x 109 x toFF 7 Calculate the switching frequency by fs 1 tON toFF where ton IR x L VIN VouT and IR VOUT x toFF L L is the inductor value Vin is the input volt age VouT is the output vol
12. inductor current reaches the current limit Vcs Vcs RSENSE the P channel FET turns off and the N channel FET synchronous rectifier turns on Inductor energy is delivered to the load as the current ramps down This ramp rate depends on Rtorr and inductor values When off time expires the P channel FET turns back on and the N channel FET turns off Two digital inputs DO and D1 select between four pos sible current levels Table 1 In pulse trickle mode the MAA 1 2 IR7309 MAXIM MAX1640 DO D1 Figure 2b Standard Application Circuit part operates for 12 5 of the period set by RTOFF resulting in a lower current for pulse trickle charging Figure 1 is the MAX1640 MAX1641 functional diagram Figure 2 shows the standard application circuits Charge Mode Programming the Output Currents The sense resistor RSENSE sets two charging current levels Choose between these two levels by holding DO high and toggling D1 either high or low Table 1 The fast charge current level equals Vcs RSENSE where Vcs is the full scale current sense voltage of 150mV Alternatively calculate this current by VREF 13 3RSENSE The top off current equals VSET 13 3RSENSE A resistor divider from REF to GND pro grams the voltage at SET Figure 3 TV9OTXVW OV9OTXVIN MAX1640 MAX1641 Adjustable Output Switch Mode Current Source with Synchronous Rectifier The voltage at SET is given by R1 R2 VREF VsET 1 10
13. kQ lt R2 lt 300kQ where VREF 2V and VsET is proportional to the desired output current level Table 1 Selecting Output Current Levels D1 DO MODE OUTPUT CURRENT A 0 0 OFF 0 0 1 Top Off Vset 13 3RSENSE Ti VsET 13 3RSENSE 1 0 Pulse Trickle 12 5 duty cycle 1 1 Fast Charge VREF 13 3RsENSE MAXIM MAX1640 MAX1641 Figure 3 Adjusting the Output Current Level MAXI AVI MAX1640 CS Figure 4a Setting the Maximum Output Voltage Level MAXIM MAX1641 Figure 4b Setting the Maximum Output Voltage Level The MAX1640 MAX1641 are specified for VSET between OV and Vrer For VSET gt VREF output current increases linearly with reduced accuracy until it clamps at VsET 4V Pulse Trickle Mode Selecting the Pulse Trickle Current Pulling DO low and D1 high selects pulse trickle mode This current equals Vset 13 3RSENSE and remains on for 12 5 of the period set by Rtorr Pulse trickle current maintains full charge across the battery and can slowly charge a cold battery before fast charging commences PERIOD 3 2x 107 x Rrogr sec Off Mode Turning Off the Output Current Pulling DO and D1 low turns off the P channel FET and hence the output current flow This mode also controls end of charge and protects the battery against exces sive temperatures Setting the Maximum Output Voltage Level The maximum output voltage should be programmed to a level h
14. s high switching frequency demands a high speed rectifier Table 2 Schottky diodes such as the 1N5817 1N5822 are recommended Make sure the Schottky diode s average current rating exceeds the peak current limit and that its breakdown voltage exceeds the output voltage VouT For high tempera ture applications Schottky diodes may be inadequate due to their high leakage current high speed silicon diodes such as the MUR105 or EC11FS1 can be used instead At heavy loads and high temperatures the benefits of a Schottky diode s low forward voltage may outweigh the disadvantage of high leakage current If the application uses an N channel MOSFET synchro nous rectifier a parallel Schottky diode is usually unnecessary except with very high charge current gt 3 amps Best efficiency is achieved with both an N channel MOSFET and a Schottky diode Inductor Value Refer to the section Programming the Off Time to select the proper inductor value There is a trade off between 10 inductor value off time output current ripple and switching frequency Applications Information All Purpose Microcontroller Battery Charger NiCd NiMH In applications where a microcontroller is available the MAX1640 MAX1641 can be used as a low cost battery charger Figure 5 The controller takes over fast charge pulse trickle charge charge termination and other smart functions By monitoring the output voltage at VouT the controller initiates fas
15. t charge set DO and D1 high terminates fast charge and initiates top off set DO high and D1 low enters trickle charge set DO low and D1 high or shuts off and terminates current flow set DO and D1 low Layout and Grounding Due to high current levels and fast switching wave forms proper PC board layout is essential High cur rent ground paths should be connected in a star MLK Adjustable Output Switch Mode Current Source with Synchronous Rectifier configuration to PGND These traces should be wide to Chip Information reduce resistance and as short as possible to reduce ee stray inductance All low current ground paths should TRANSISTOR COUNT 1233 be connected to GND Place the input bypass capaci tor as close as possible to the IN pin See MAX1640 EV kit for layout example Package Information The package drawing s in this data sheet may not reflect the most current specifications For the latest package outline information go to www maxim ic com packages j gja INCHES MILLIMETERS VARIATIONS 5 DIM MIN MAX MIN MAX INCHES MILLIMETERS g I A 061 068 155 1 73 MIN MAX MIN MAX N i Al 004 0098 0 127 0 25 D 189 196 4 80 4 98 16 AA A2 055 061 1 4
16. tage and IR is the output peak to peak current ripple Note that RTorr sets both the off time and the pulse trickle charge period Reference The on chip reference is laser trimmed for a precise 2V at REF REF can source no more than 50A Bypass REF with a 0 1uF capacitor to ground Constant Current Loop AC Loop Compensation The constant current loop s output is brought out at CC To reduce noise due to variations in switching currents bypass CC with a inF to 100nF capacitor to ground A large capacitor value maintains a constant average out put current but slows the loop response to changes in switching current A small capacitor value speeds up the loop response to changes in switching current MAA generating increased ripple at the output Select Ccc to optimize the ripple vs loop response Synchronous Rectification Synchronous rectification reduces conduction losses in the rectifier by shunting the Schottky diode with a low resistance MOSFET switch In turn efficiency increases by about 3 to 5 at heavy loads To prevent cross conduction or shoot through the synchronous rectifier turns on shortly after the P channel power MOSFET Table 2 Component Manufacturers COMPONENT MANUFACTURER Sumida CDRH125 series Inductor Coilcraft D03316P series Coiltronics UP2 series International Rectifier IRF7309 MOSPETS Siliconix S14539DY Sense Resistor Dale WSL 2010 series
17. tage Range VIN 5 5 26 V Linear Regulator Output V VIN 5 5V to 26V VIN VIN v Voltage Vin Referenced LDOH itoan 0 to 20mA 55 45 Linear Regulator Output VIN 5 5V to 26V Voltage Ground Referenced VLDOL ILOAD 0 to 20mA sn 5 5 y Full Scale Current Sense MAX1640 141 159 mV Threshold MAX1641 146 154 Quarter Scale Current Sense MAX1640 34 48 mV Threshold MAX1641 33 42 Output Current Compliance VouT 2V to 24V MAX1640 0 4 AIN Quiescent Vin Supply Current DO or D1 high 4 mA Output Current in Off Mode DO D1 low 1 pA VLpoL Undervoltage Lockout 4 0 4 4 Reference Voltage VREF 1 94 2 06 Reference Load Regulation IREF 0 to 50A 10 mV VseT Input Current 1 yA FET Drive Output Resistance 12 Q Off Time Range 1 5 8 us Off Time Accuracy RTOFF 62kQ 1 5 2 5 Us Pulse Trickle Mode Duty Cycle DO low D1 high Rrorr 50kQ 25 42 s Period PWM Maximum Duty Cycle 100 Input Low Voltage VIL DO D1 0 8 V Input High Voltage VIH DO D1 2 4 V Input Leakage Current IIN DO D1 1 pA MAALSVI 3 TV9OTXVW OVOTXVIN MAX1640 MAX1641 Adjustable Output Switch Mode Current Source with Synchronous Rectifier Typical Operating Characteristics Circuit of Figure 2 Ta 25 C unless otherwise noted 100 90 80 70 EFFICIENCY 60 50 40 1 550 1 525 1 500 QUTPUT CURENT A 1 475 1 450 EFFICIENCY vs OUTPUT VOLTAGE 1 510 1 500 MAX164041 TO001 1 490 1 480 OUTPUT CURFENT A
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MAXIM MAX1640/MAX1641 Manual