19-1158; Rev 1; 12/02 Chemistry-Independent Battery Chargers The MAX1647 is available in a 20-pin SSOP with a 2mm profile height. The MAX1648 is available in a 16-pin SO package. ________________________Applications Notebook Computers Personal Digital Assistants ____________________________Features ♦ Charges Any Battery Chemistry: Li-Ion, NiCd, NiMH, Lead Acid, etc. ♦ Intel SMBus 2-Wire Serial Interface (MAX1647) ♦ Intel/Duracell Level 2 Smart Battery Compliant (MAX1647) ♦ 4A, 2A, or 1A Maximum Battery-Charge Current ♦ 11-Bit Control of Charge Current ♦ Up to 18V Battery Voltage ♦ 10-Bit Control of Voltage ♦ ±0.75% Voltage Accuracy with External ±0.1% Reference ♦ Up to 28V Input Voltage ♦ Battery Thermistor Fail-Safe Protection ______________Ordering Information TEMP RANGE PIN-PACKAGE MAX1647EAP PART -40°C to +85°C 20 SSOP MAX1648ESE -40°C to +85°C 16 Narrow SO Charger Base Stations Phones __________________________________________________________Pin Configurations TOP VIEW IOUT 1 20 BST DCIN 2 19 LX VL 3 CCV 4 CCI 5 MAX1647 SEL 6 18 DHI VL 2 17 DLO CCV 3 16 PGND CCI 4 15 DACV 14 DHI MAX1648 13 DLO 12 PGND 11 SETV 10 SETI CS 7 14 SDA BATT 8 13 SCL REF 7 REF 9 12 THM AGND 8 11 INT 15 LX CS 5 BATT 6 AGND 10 16 BST DCIN 1 9 THM SO SSOP SMBus is a trademark of Intel Corp. ________________________________________________________________ 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 MAX1647/MAX1648 _______________General Description The MAX1647/MAX1648 provide the power control necessary to charge batteries of any chemistry. In the MAX1647, all charging functions are controlled through the Intel System Management Bus (SMBus™) interface. The SMBus 2-wire serial interface sets the charge voltage and current, and provides thermal status information. The MAX1647 functions as a level 2 charger, compliant with the Duracell/Intel Smart Battery Charger Specification. The MAX1648 omits the SMBus serial interface, and instead sets the charge voltage and current proportional to the voltage applied to external control pins. In addition to the feature set required for a level 2 charger, the MAX1647 generates interrupts to signal the host when power is applied to the charger or a battery is installed or removed. Additional status bits allow the host to check whether the charger has enough input voltage, and whether the voltage on or current into the battery is being regulated. This allows the host to determine when lithiumion batteries have completed charge without interrogating the battery. MAX1647/MAX1648 Chemistry-Independent Battery Chargers ABSOLUTE MAXIMUM RATINGS DCIN to AGND..........................................................-0.3V to 30V DCIN to IOUT...........................................................-0.3V to 7.5V BST to AGND ............................................................-0.3V to 36V BST, DHI to LX ............................................................-0.3V to 6V LX to AGND ..............................................................-0.3V to 30V THM, CCI, CCV, DACV, REF, DLO to AGND ................................................-0.3V to (VL + 0.3V) VL, SEL, INT, SDA, SCL to AGND (MAX1647) ...........-0.3V to 6V SETV, SETI to AGND (MAX1648)................................-0.3V to 6V BATT, CS+ to AGND.................................................-0.3V to 20V PGND to AGND .....................................................-0.3V to +0.3V SDA, INT Current ................................................................50mA VL Current ...........................................................................50mA Continuous Power Dissipation (TA = +70°C) 16-Pin SO (derate 8.7mW/°C above +70°C).................696mW 20-Pin SSOP (derate 8mW/°C above +70°C) ...............640mW Operating Temperature Range MAX1647EAP, MAX1648ESE ...........................-40°C to +85°C Storage Temperature.........................................-60°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 (VDCIN = 18V, VREF = 4.096V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS SUPPLY AND REFERENCE DCIN Input Voltage Range 7.5 DCIN Quiescent Current 7.5V < VDCIN < 28V, logic inputs = VL VL Output Voltage 7.5V < VDCIN < 28V, no load VL Load Regulation ILOAD = 10mA VL AC_PRESENT Trip Point MAX1647 3.20 REF Output Voltage 0µA < ISOURCE < 500µA 3.74 5.15 28.0 V 4 6 mA 5.4 5.65 V 100 mV 4 5.15 V 3.9 4.07 V 700 µA 300 kHz REF Overdrive Input Current SWITCHING REGULATOR Oscillator Frequency 200 250 DHI Maximum Duty Cycle 89 93 % DHI On-Resistance High or low 4 7 Ω DLO On-Resistance High or low 6 14 Ω VL < 3.2V, VBATT = 12V 1 5 VL < 5.15V, VBATT = 12V 350 500 VL < 3.2V, VCS = 12V 1 5 VL < 5.15V, VCS = 12V 170 400 BATT Input Current (Note 1) CS Input Current (Note 1) BATT, CS Input Voltage Range 0 CS to BATT Single-Count Current-Sense Voltage MAX1647, SEL = open, ChargingCurrent( ) = 0x0020 CS to BATT Full-Scale Current-Sense Voltage MAX1647, SEL = open, ChargingCurrent( ) = 0x07F0; MAX1648, VSETI = 1.024V Voltage Accuracy MAX1647, ChargingVoltage( ) = 0x1060, ChargingVoltage( ) = 0x3130; MAX1648, VSETV = 3.15V, VSETV = 1.05V 2 19 2.94 170 185 -0.65 _______________________________________________________________________________________ µA µA V mV 200 mV +0.65 % Chemistry-Independent Battery Chargers MAX1647/MAX1648 ELECTRICAL CHARACTERISTICS (continued) (VDCIN = 18V, VREF = 4.096V, TA = 0°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNITS ERROR AMPLIFIERS GMV Amplifier Transconductance 1.4 mA/V GMI Amplifier Transconductance 0.2 mA/V GMV Amplifier Maximum Output Current ±80 µA GMI Amplifier Maximum Output Current ±200 µA CCI Clamp Voltage with Respect to CCV 1.1V < VCCV < 3.5V 25 80 200 mV CCV Clamp Voltage with Respect to CCI 1.1V < VCCI < 3.5V 25 80 200 mV TRIP POINTS AND LINEAR CURRENT SOURCES BATT POWER_FAIL Trip Point MAX1647 86.5 89 91.5 % of VDCIN THM THERMISTOR_OR Over-Range Trip Point MAX1647 89.5 91 92.5 % of VREF THM THERMISTOR_COLD Trip Point 74 75.5 77 % of VREF THM THERMISTOR_HOT Trip Point 22 23.5 25 % of VREF 3 4.5 6 % of VREF 25 31 38 mA 10 µA -1.0 V THM THERMISTOR_UR Under-Range Trip Point MAX1647 IOUT Output Current MAX1647, VDCIN = 7.5V, VIOUT = 0V IOUT Operating Voltage Range With respect to DCIN voltage ChargingCurrent( ) = 0x001F ChargingCurrent( ) = 0x0000 -7.5 CURRENT- AND VOLTAGE-SETTING DACs (MAX1647) CDAC Current-Setting DAC Resolution Guaranteed monotonic 6 Bits VDAC Voltage-Setting DAC Resolution Guaranteed monotonic 10 Bits SETV, SETI (MAX1648) SETV Input Bias Current 1 µA SETI Input Bias Current 5 µA SETV Input Voltage Range 0 4.2 V SETI Input Voltage Range 0 1.024 V 0.8 V +1 µA LOGIC LEVELS (MAX1647) SDA, SCL Input Low Voltage SDA, SCL Input High Voltage 2.8 SDA, SCL Input Bias Current -1 SDA Output Low Sink Current VSDA = 0.6V V 6 mA Note 1: When DCIN is less than 4V, VL is less than 3.2V, causing the battery current to be typically 2µA (CS plus BATT input current). _______________________________________________________________________________________ 3 MAX1647/MAX1648 Chemistry-Independent Battery Chargers ELECTRICAL CHARACTERISTICS (VDCIN = 18V, VREF = 4.096V, TA = -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted. Limits over this temperature range are guaranteed by design.) PARAMETER CONDITIONS MIN TYP MAX UNITS 4 6 mA SUPPLY AND REFERENCE DCIN Quiescent Current 7.5V < VDCIN < 28V, logic inputs = VL VL Output Voltage 7.5V < VDCIN < 28V, no load 5.15 5.4 5.65 V REF Output Voltage 0µA < ISOURCE < 500µA 3.74 3.9 4.07 V Oscillator Frequency 200 250 310 kHz DHI Maximum Duty Cycle 89 SWITCHING REGULATOR % DHI On-Resistance High or low 4 7 Ω DLO On-Resistance High or low 6 14 Ω BATT Input Current VL < 3.2V, VBATT = 12V 5 µA CS Input Current VL < 3.2V, VCS = 12V 5 µA CS to BATT Full-Scale Current-Sense Voltage MAX1647, SEL = open, ChargingCurrent( ) = 0x07F0; MAX1648, VSETI = 1.024V 200 mV Voltage Accuracy MAX1647, ChargingVoltage( ) = 0x1060, ChargingVoltage( ) = 0x3130; MAX1648, VSETV = 3.15V, VSETV = 1.05V +0.65 % 160 185 -0.65 ERROR AMPLIFIERS GMV Amplifier Transconductance 1.4 mA/V GMI Amplifier Transconductance 0.2 mA/V GMV Amplifier Maximum Output Current ±130 µA GMI Amplifier Maximum Output Current ±320 µA TRIP POINTS AND LINEAR CURRENT SOURCES THM THERMISTOR_OR Over-Range Trip Point 89.5 91 92.5 % of VREF THM THERMISTOR_COLD Trip Point 74 75.5 77 % of VREF THM THERMISTOR_HOT Trip Point 22 23.5 25 % of VREF 3 4.5 6 % of VREF SETV Input Bias Current 1 µA SETI Input Bias Current 5 µA 0.8 V THM THERMISTOR_UR Under-Range Trip Point MAX1647 MAX1647 SETV, SETI (MAX1648) LOGIC LEVELS (MAX1647) SDA, SCL Input Low Voltage SDA, SCL Input High Voltage 2.8 SDA, SCL Input Bias Current SDA Output Low Sink Current 4 -1 VSDA = 0.6V 6 _______________________________________________________________________________________ V +1 µA mA Chemistry-Independent Battery Chargers MAX1647/MAX1648 TIMING CHARACTERISTICS—MAX1647 (TA = 0°C to +85°C, unless otherwise noted.) PARAMETER SCL Serial-Clock High Period SCL Serial-Clock Low Period SYMBOL CONDITIONS MIN TYP MAX UNITS tHIGH 4 µs tLOW 4.7 µs Start-Condition Setup Time tSU:STA 4.7 µs Start-Condition Hold Time tHD:STA 4 µs SDA Valid to SCL Rising-Edge Setup Time, Slave Clocking in Data tSU:DAT 250 ns SCL Falling Edge to SDA Transition tHD:DAT 0 ns SCL Falling Edge to SDA Valid, Master Clocking in Data tDV 1 µs MAX UNITS TIMING CHARACTERISTICS—MAX1647 (TA = -40°C to +85°C, unless otherwise noted. Limits over this temperature range are guaranteed by design.) PARAMETER SYMBOL CONDITIONS MIN TYP SCL Serial-Clock High Period tHIGH 4 µs SCL Serial-Clock Low Period tLOW 4.7 µs Start-Condition Setup Time tSU:STA 4.7 µs Start-Condition Hold Time tHD:STA 4 µs SDA Valid to SCL Rising-Edge Setup Time, Slave Clocking in Data tSU:DAT 250 ns SCL Falling Edge to SDA Transition tHD:DAT 0 ns SCL Falling Edge to SDA Valid, Master Clocking in Data tDV 1 µs _______________________________________________________________________________________ 5 __________________________________________Typical Operating Characteristics (Circuit of Figure 3, TA = +25°C, unless otherwise noted.) MAX1647 BATT LOAD TRANSIENT MAX1647 BATT LOAD TRANSIENT MAX1647/48-02 MAX1647/48-01 1.1A TO 0.9A TO 1.1A CCI CCI VCCV 2.3V VCCI 100mV/div CCV CCV VCCI 2.4V VCCV 200mV/div CCI CCV 12V CCV CCV CCI CCI VBATT 1V/div 12V VBATT 5V/div 0.9A TO 1.9A TO 0.9A 2ms/div 1ms/div ChargingVoltage( ) = 0x2EE0 = 12000mV ChargingCurrent( ) = 0x03E8 = 1000mA ACDCIN = 18.0V, SEL = OPEN, C1 = 68µF, C2 = 0.1µF, C3 = 47nF, R1 = 0.1Ω R2 = 10kΩ, L1 = 22µH, VREF = 4.096V ChargingVoltage( ) = 0x2EE0 = 12000mV ChargingCurrent( ) = 0xFFFF = MAX VALUE ACDCIN = 18.0V, SEL = OPEN, R1 = 0.1Ω R2 = 10kΩ, C1 = 68µF, C2 = 0.1µF, C3 = 47nF L1 = 22µH, VREF = 4.096V VL VOLTAGE vs. LOAD CURRENT INTERNAL REFERENCE VOLTAGE 5.0 MAX1647/48-04 3.86 MAX1647/48-03 5.5 3.84 3.82 VL (V) VREF (V) 4.5 4.0 3.80 3.78 3.76 3.74 3.5 CIRCUIT OF FIGURE 3 VDCIN = 6.6V 3.72 0 3.70 10 20 30 50 40 0.5 0 LOAD CURRENT (mA) MAX1647 OUTPUT V-I CHARACTERISTIC 25 20 POWER INTO CIRCUIT 15 10 POWER TO BATT 5 0 6 500 1000 1500 2000 CURRENT INTO BATT (mA) 2500 2.0 MAX1647/48-06 BATT NO-LOAD OUTPUT VOLTAGE = 16.384V 0.01 OUTPUT VOLTAGE ERROR 0.1 1 10 VDCIN = 28V, VREF = 4.096V ChargingVoltage( ) = 0xFFFF ChargingCurrent( ) = 0xFFFF 100 0 1.5 0.8 OUTPUT VOLTAGE ERROR (%) 30 0.001 DROP IN BATT OUTPUT VOLTAGE (%) VDCIN = 28V VBATT = 12.6V ChargingCurrent( ) = 0xFFFF ChargingVoltage( ) = 0xFFFF 35 MAX1647/48-05 INPUT AND OUTPUT POWER 40 1.0 LOAD CURRENT (mA) MAX1647/48-07 0 POWER (W) MAX1647/MAX1648 Chemistry-Independent Battery Chargers 0.6 3mA LOAD 0.4 0.2 0 300mA LOAD -0.2 -0.4 0 500 1000 1500 LOAD CURRENT (mA) 2000 2500 4500 8500 12,500 16,500 PROGRAMMED VOLTAGE CODE IN DECIMAL _______________________________________________________________________________________ Chemistry-Independent Battery Chargers PIN NAME FUNCTION MAX1647 MAX1648 1 — IOUT Linear Current-Source Output 2 1 DCIN Input Voltage for Powering Charger 3 2 VL 4 3 CCV Voltage-Regulation-Loop Compensation Point 5 4 CCI Current-Regulation-Loop Compensation Point 6 — SEL Current-Range Selector. Tying SEL to VL sets a 4A full-scale current. Leaving SEL open sets a 2A full-scale current. Tying SEL to AGND sets a 1A full-scale current. 7 5 CS Current-Sense Positive Input 8 6 BATT 9 7 REF 10 8 AGND — 10 SETI Current-Regulation-Loop Set Point 11 — INT Open-Drain Interrupt Output — 11 SETV Voltage-Regulation-Loop Set Point 12 9 THM Thermistor Sense Voltage Input 13 — SCL Serial Clock 14 — SDA Serial Data 15 — DACV Voltage DAC Output 16 12 PGND Power Ground 17 13 DLO Low-Side Power MOSFET Driver Output 18 14 DHI High-Side Power MOSFET Driver Output 19 15 LX Power Connection for the High-Side Power MOSFET Driver 20 16 BST Power Connection for the High-Side Power MOSFET Driver Chip Power Supply. 5.4V linear regulator output from DCIN. Battery Voltage Input and Current-Sense Negative Input 3.9V Reference Voltage Output or External Reference Input Analog Ground _______________________________________________________________________________________ 7 MAX1647/MAX1648 ______________________________________________________________Pin Description MAX1647/MAX1648 Chemistry-Independent Battery Chargers START CONDITION MOST SIGNIFICANT ADDRESS BIT (A6) CLOCKED INTO SLAVE A5 CLOCKED INTO SLAVE A4 CLOCKED INTO SLAVE A3 CLOCKED INTO SLAVE SCL tHIGH tLOW tHD:STA SDA tSU:STA tSU:DAT tHD:DAT tSU:DAT tHD:DAT Figure 1. SMBus Serial Interface Timing—Address MOST SIGNIFICANT BIT OF DATA CLOCKED INTO MASTER ACKNOWLEDGE BIT CLOCKED INTO MASTER RW BIT CLOCKED INTO SLAVE SCL SLAVE PULLING SDA LOW SDA tDV tDV Figure 2. SMBus Serial Interface Timing—Acknowledge 8 _______________________________________________________________________________________ Chemistry-Independent Battery Chargers 6 GND MAX1647/MAX1648 4 VIN 2 MAX874 VOUT 10 D5 IOUT AGND 1 Q1 C9 C4 DCIN 9 SEL REF VL 2 6 N.C. R6 R7 D6 3 R3 R4 12 THM R5 C5 (NOTE 2) MAX1647 D4* C6 D2 BST 5 CCI DHI 20 DC SOURCE M1 18 C3 C7 LX DLO 4 7.5V–28V 19 17 D1 L1 M2 CCV PGND R2 16 D3 (NOTE 1) C1 C2 CS 7 R1A R1B SDA INT 13 14 11 = HIGH-CURRENT TRACES (8A MAX) NOTE 1: C6, M2, D1, AND C1 GROUNDS MUST CONNECT TO THE SAME RECTANGULAR PAD ON THE LAYOUT. NOTE 2: C5 MUST BE PLACED WITHIN 0.5cm OF THE MAX1647, WITH TRACES NO LONGER THAN 1cm CONNECTING VL AND PGND. *OPTIONAL (SEE NEGATIVE INPUT VOLTAGE PROTECTION SECTION). GND SCL 8 KINT- C8 BATT SMBDATA DACV SMBCLOCK 15 - T D C + SMART BATTERY STANDARD CONNECTOR HOST AND LOAD Figure 3. MAX1647 Typical Application Circuit _______________________________________________________________________________________ 9 MAX1647/MAX1648 Chemistry-Independent Battery Chargers Table 1a. Component Selection for Figure 3 Circuit (Also Use for Figure 4) DESIGNATION QTY UNITS NOTES C1 47 µF 20V, ESR at 250kHz ≤ 0.4Ω C2, C4, C7, C9 C3 C5 C6 C8 0.1 47 1 22 22 µF nF µF µF nF 10V, ceramic or low ESR 35V 10V 3A IDC, 30V Schottky diode, PD > 0.8W, 1N5821 equivalent D1, D3, D4 NIEC, NSQ03A04, FLAT-PAK (SMC) NIEC, 30VQ04F, TO-252AA (SMD) Motorola, MBRS340T3, SMC Motorola, MBRD340T4, DPAK Diodes Inc., SK33, SMC IR, 30BQ040, SMC 50mA IDC, 40V fast-recovery diode, 1N4150 equivalent D2, D5 D6 4.3V zener diode, 1N4731 or equivalent L1 ±20%, 3A ISAT Note: size in L x W x H Sumida, RCH-110/220M, 10mm x 10mm x 10mm Coiltronics, UP2-220, 0.541" x 0.345" x 0.231" Coilcraft, DO3340P-223, 0.510" x 0.370" x 0.450" Coilcraft, DO5022P-223, 0.730" x 0.600" x 0.280" RDS, ON ≤ 0.1Ω, VDSS ≥ 30V, PD > 0.5W, logic level, N-channel power MOSFET Motorola, MMSF5N03HD, SO-8 Motorola, MMDF3N03HD, SO-8 Motorola, MTD20N03HDL, DPAK IR, IRF7201, SO-8 IR, IRF7303, SO-8 IR, IRF7603, Micro8 Siliconix, Si9410DY, SO-8 Siliconix, Si9936DY, SO-8 Siliconix, Si6954DQ, TSSOP-8 M2 RDS, ON ≤ 10Ω, VDSS ≥ 30V, logic level, N-channel power MOSFET, 2N7002 equivalent Motorola, 2N7002LT1, SOT23 Motorola, MMBF170LT1, SOT23 Diodes Inc., 2N7002, SOT23 Diodes Inc., BS870, SOT23 Zetex, ZVN3306F, SOT23 Central Semiconductor, 2N7002, SOT23 Q1 VCE, MAX ≤ -30V, 50mA IC, CONT, 2N3906 equivalent 22 µH M1 R1A 10 SOURCE/TYPE Sprague, 595D476X0020D7T, D case AVX, TPSE476M020R0150, E case 100 mΩ ±1%, 1W R1B 1 Ω ±5%, 1/8W R2, R4 10 kΩ ±5%, 1/16W R3 10 kΩ ±1%, 1/16W R5, R7 10 Ω ±5%, 1/16W R6 10 kΩ ±5%, 1/8W IRC, CHP1100R100F13, 2512 IRC, LR251201R100F, 2512 Dale, WSL-2512/0.1Ω/±1%, 2512 ______________________________________________________________________________________ Chemistry-Independent Battery Chargers MANUFACTURER PHONE Output Characteristics FAX AVX 803-946-0690 803-626-3123 Central Semiconductor 516-435-1110 516-435-1824 Coilcraft 847-639-6400 847-639-1469 Coiltronics 561-241-7876 561-241-9339 Dale 605-668-4131 605-665-1627 IR 310-322-3331 310-322-3332 IRC 512-992-7900 512-992-3377 NIEC 805-867-2555 805-867-2698 Siliconix 408-988-8000 408-970-3950 Sprague 603-224-1961 603-224-1430 Sumida 847-956-0666 847-956-0702 Zetex 516-543-7100 516-864-7630 The MAX1647/MAX1648 contain both a voltageregulation loop and a current-regulation loop. Both loops operate independently of each other. The voltage-regulation loop monitors BATT to ensure that its voltage never exceeds the voltage set point (V0). The current-regulation loop monitors current delivered to BATT to ensure that it never exceeds the current-limit set point (I0). The current-regulation loop is in control as long as BATT voltage is below V0. When BATT voltage reaches V0, the current loop no longer regulates, and the voltage-regulation loop takes over. Figure 5 shows the V-I characteristic at the BATT pin. C4 C5 REF R3 VL R4 THM R5 MAX1648 D2 CCI C3 DCIN D4 C6 M1 DHI DC SOURCE BST 7.5V–28V L1 C7 CCV LX D1 R2 DLO C2 D3 M2 PGND R8 CS R1 SETI R9 BATT R10 C1 SETV AGND BATTERY R11 T Figure 4. MAX1648 Typical Operating Circuit ______________________________________________________________________________________ 11 MAX1647/MAX1648 _______________Detailed Description Table 1b. Component Suppliers MAX1647/MAX1648 Chemistry-Independent Battery Chargers Whether the MAX1647 is controlling the voltage or current at any time depends on the battery’s state. If the battery has been discharged, the MAX1647’s output reaches the current-regulation limit before the voltage limit, causing the system to regulate current. As the battery charges, the voltage rises until the voltage limit is reached, and the charger switches to regulating voltage. The transition from current to voltage regulation is done by the charger, and need not be controlled by the host. BATT VOLTAGE V0 V0 = VOLTAGE SET POINT I0 = CURRENT-LIMIT SET POINT Voltage Control I0 AVERAGE CURRENT THROUGH THE RESISTOR BETWEEN CS AND BATT Figure 5. Output V-I Characteristic Setting V0 and I0 (MAX1647) Set the MAX1647’s voltage and current-limit set points through the Intel System Management Bus (SMBus) 2wire serial interface. The MAX1647’s logic interprets the serial-data stream from the SMBus interface to set internal digital-to-analog converters (DACs) appropriately. See the MAX1647 Logic section for more information. Setting V0 and I0 (MAX1648) Set the MAX1648’s voltage- and current-limit set points (V0 and I0, respectively) using external resistive dividers. Figure 6b is the MAX1648 block diagram. V0 equals four times the voltage on the SETV pin. I0 equals the voltage on SETI divided by 5.5, divided by R1 (Figure 4). _____________________Analog Section The MAX1647/MAX1648 analog section consists of a current-mode PWM controller and two transconductance error amplifiers: one for regulating current and the other for regulating voltage. The MAX1647 uses DACs to set the current and voltage level, which are controlled through the SMBus interface. The MAX1648 eliminates the DACs and controls the error amplifiers directly from SETI (for current) and SETV (for voltage). Since separate amplifiers are used for voltage and current control, both control loops can be compensated separately for optimum stability and response in each state. The following discussion relates to the MAX1647; however, MAX1648 operation can easily be inferred from the MAX1647. 12 The internal GMV amplifier controls the MAX1647’s output voltage. The voltage at the amplifier’s noninverting input amplifier is set by a 10-bit DAC, which is controlled by a ChargingVoltage( ) command on the SMBus (see the MAX1647 Logic section for more information). The battery voltage is fed to the GMV amplifier through a 4:1 resistive voltage divider. With an external 4.096V reference, the set voltage ranges between 0 and 16.38V with 16mV resolution. This poses a challenge for charging four lithium-ion cells in series: because the lithium-ion battery’s typical per-cell voltage is 4.2V maximum, 16.8V is required. A larger reference voltage can be used to circumvent this. Under this condition, the maximum battery voltage no longer matches the programmed voltage. The solution is to use a 4.2V reference and host software. Contact Maxim’s applications department for more information. The GMV amplifier’s output is connected to the CCV pin, which compensates the voltage-regulation loop. Typically, a series-resistor/capacitor combination can be used to form a pole-zero couplet. The pole introduced rolls off the gain starting at low frequencies. The zero of the couplet provides sufficient AC gain at midfrequencies. The output capacitor then rolls off the midfrequency gain to below 1, to guarantee stability before encountering the zero introduced by the output capacitor’s equivalent series resistance (ESR). The GMV amplifier’s output is internally clamped to between onefourth and three-fourths of the voltage at REF. Current Control The internal GMI amplifier and an internal current source control the battery current while the charger is regulating current. Since the regulator current’s accuracy is not adequate to ensure full 11-bit accuracy, an internal linear current source is used in conjunction with the PWM regulator to set the battery current. The current-control DAC’s five least significant bits set the ______________________________________________________________________________________ Chemistry-Independent Battery Chargers 10kΩ 10kΩ 10kΩ DCIN 10kΩ 8mA 16mA THERMISTOR_OR 4mA 2mA 1mA 5 IOUT THERM_SHUT THERMAL SHUTDOWN THERMISTOR_COLD SEL LOGIC BLOCK THM SCL THERMISTOR_HOT SDA DCIN INT VL THERMISTOR_UR 30kΩ 100kΩ 3kΩ AC_PRESENT 5.4V LINEAR REGULATOR 500Ω INTERNAL 3.9V REFERENCE REF AGND AGND CCV CCV_LOW 3R REF CS CURRENT-SENSE LEVEL SHIFT AND GAIN OF 5.5 BATT R AGND REF FROM LOGIC BLOCK 6 3/8 REF = ZERO CURRENT 6-BIT DAC CCI R BST NOTE: APPROX. REF/4 + VTHRESH TO 3/4 REF + VTHRESH LEVEL SHIFT GMI DRIVER DHI NOTE: REF/4 TO 3/4 REF R R SUMMING COMPARATOR BLOCK R FROM LOGIC BLOCK BATT AGND TO LOGIC BLOCK TO LOGIC BLOCK R MIN VOLTAGE_INREG CURRENT_INREG CLAMP R GMV R VL CLAMP TO REF (MAX) AGND R LX DRIVER FROM LOGIC BLOCK DLO PGND CCV REF AGND FROM LOGIC BLOCK 10 10-BIT DAC AGND TO LOGIC BLOCK DACV POWER_FAIL DCIN/4.5 Figure 6a. MAX1647 Block Diagram ______________________________________________________________________________________ 13 MAX1647/MAX1648 REF MAX1647/MAX1648 Chemistry-Independent Battery Chargers REF 10kΩ 10kΩ THERMISTOR_COLD THM THERMISTOR_HOT 30kΩ 3kΩ AGND DCIN VL AC_PRESENT CS BATT 5.4V LINEAR REGULATOR CURRENT-SENSE LEVEL SHIFT AND GAIN OF 5.5 ON INTERNAL 3.9V REFERENCE REF AGND BST LEVEL SHIFT CCI DRIVER DHI GMI LX SETI REF / 2 = ZERO CURRENT BATT CLAMP MIN SUMMING COMPARATOR BLOCK ON VL R DRIVER GMV R R R CCV AC_PRESENT AND NOT (THERMISTOR_HOT OR THERMISTOR_COLD) AGND SETV Figure 6b. MAX1648 Block Diagram 14 ______________________________________________________________________________________ PGND DLO Chemistry-Independent Battery Chargers The GMI amplifier’s noninverting input is driven by a 4:1 resistive voltage divider, which is driven by the 6-bit DAC. If an external 4.096V reference is used, this input is approximately 1.0V at full scale, and the resolution is 16mV. The current-sense amplifier drives the inverting input to the GMI amplifier. It measures the voltage across the current-sense resistor (R SEN ) (which is between the CS and BATT pins), amplifies it by approximately 5.45, and level shifts it to ground. The full-scale current is approximately 0.2V / RSEN, and the resolution is 3.2mV / RSEN. The current-regulation-loop is compensated by adding a capacitor to the CCI pin. This capacitor sets the current-feedback loop’s dominant pole. The GMI amplifier’s output is clamped to between approximately one-fourth and three-fourths of the REF voltage. While the current is in regulation, the CCV voltage is clamped to within 80mV of the CCI voltage. This prevents the battery voltage from overshooting when the DAC voltage setting is updated. The converse is true when the voltage is in regulation and the current is not at the current DAC setting. Since the linear range of CCI or CCV is about 1.5V to 3.5V or about 2V, the 80mV clamp results in a relatively negligible overshoot when the loop switches from voltage to current regulation or vice versa. PWM Controller The battery voltage or current is controlled by the current-mode, pulse-width-modulated (PWM), DC-DC converter controller. This controller drives two external N-channel MOSFETs, which switch the voltage from the input source. This switched voltage feeds an inductor, which filters the switched rectangular wave. The controller sets the pulse width of the switched voltage so that it supplies the desired voltage or current to the battery. The heart of the PWM controller is the multi-input comparator. This comparator sums three input signals to determine the pulse width of the switched signal, setting the battery voltage or current. The three signals are the current-sense amplifier’s output, the GMV or GMI error amplifier’s output, and a slope-compensation signal, which ensures that the controller’s internal currentcontrol loop is stable. The PWM comparator compares the current-sense amplifier’s output to the higher output voltage of either the GMV or the GMI amplifier (the error voltage). This current-mode feedback corrects the duty ratio of the switched voltage, regulating the peak battery current and keeping it proportional to the error voltage. Since the average battery current is nearly the same as the peak current, the controller acts as a transconductance amplifier, reducing the effect of the inductor on the output filter LC formed by the output inductor and the battery’s parasitic capacitance. This makes stabilizing the circuit easy, since the output filter changes from a complex second-order RLC to a first-order RC. To preserve the inner current-control loop’s stability, slope compensation is also fed into the comparator. This damps out perturbations in the pulse width at duty ratios greater than 50%. At heavy loads, the PWM controller switches at a fixed frequency and modulates the duty cycle to control the battery voltage or current. At light loads, the DC current through the inductor is not sufficient to prevent the current from going negative through the synchronous rectifier (Figure 3, M2). The controller monitors the current through the sense resistor RSEN; when it drops to zero, the synchronous rectifier turns off to prevent negative current flow. MOSFET Drivers The MAX1647 drives external N-channel MOSFETs to regulate battery voltage or current. Since the high-side N-channel MOSFET’s gate must be driven to a voltage higher than the input source voltage, a charge pump is used to generate such a voltage. The capacitor C7 (Figure 3) charges to approximately 5V through D2 when the synchronous rectifier turns on. Since one side of C7 is connected to the LX pin (the source of M1), the high-side driver (DHI) can drive the gate up to the voltage at BST, which is greater than the input voltage, when the high-side MOSFET turns on. The synchronous rectifier behaves like a diode, but with a smaller voltage drop to improve efficiency. A small dead time is added between the time that the high-side MOSFET turns off and the synchronous rectifier turns on, and vice versa. This prevents crowbar currents (currents that flow through both MOSFETS during the brief time that one is turning on and the other is turning off). Connect a Schottky rectifier from ground to LX (across the source and drain of M2) to prevent the synchronous rectifier’s body diode from conducting. The body diode typically has slower switching-recovery times, so allowing it to conduct would degrade efficiency. ______________________________________________________________________________________ 15 MAX1647/MAX1648 internal current sources’ state, and the six most significant bits control the switching regulator’s current. The internal current source supplies 1mA resolution to the battery to comply with the smart-battery specification. When the current is set to a number greater than 32, the internal current source remains at 31mA. This guarantees that battery-current setting is monotonic regardless of current-sense resistor choice and current-sense amplifier offset. The synchronous rectifier may not be completely replaced by a diode because the BST capacitor charges while the synchronous rectifier is turned on. Without the synchronous rectifier, the BST capacitor may not fully charge, leaving the high-side MOSFET with insufficient gate drive to turn on. However, the synchronous rectifier can be replaced with a small MOSFET, such as a 2N7002, to guarantee that the BST capacitor is allowed to charge. In this case, most of the current at high currents is carried by the diode and not by the synchronous rectifier. BOLD LINE INDICATES THAT THE MAX1647 PULLS SDA LOW ACK D8 ChargingMode( ) = 0 x 12 ChargingVoltage( ) = 0 x 15 ChargingCurrent( ) = 0 x 14 AlarmWarning( ) = 0 x 16 ChargerStatus( ) = 0 x 13 D9 D10 D11 D12 D13 D14 Internal Regulator and Reference D15 D2 THERMISTOR_HOT D3 THERMISTOR_UR D4 ALARM_INHIBITED D5 POWER_FAIL D6 BATTERY_PRESENT D7 AC_PRESENT CMD2 CMD3 CMD4 CMD5 CMD6 CMD7 ACK MAX1647 Logic W 1 0 0 1 0 0 0 SDA START ACK 1 CHARGE_INHIBITED 1 MASTER_MODE 0 VOLTAGE_NOTREG 0 CURRENT_NOTREG 1 LEVEL_2 0 LEVEL_3 0 CURRENT_OR 0 VOLTAGE_OR ACK ACK W R 1 1 0 0 0 0 1 1 0 0 0 0 0 0 START REPEATED START SDA CMD1 ACK SCL WRITE WORD: ChargingMode( ), ChargingVoltage( ), ChargingCurrent( ), AlarmWarning( ) ACK CMD0 Figure 7. Write-Word and Read-Word Examples ______________________________________________________________________________________ READ WORD: ChargersStatus( ) THERMISTOR_COLD SDA THERMISTOR_OR D1 SCL D0 The MAX1647 uses serial data to control its operation. The serial interface complies with the SMBus specification (see System Management Bus Specification, from Intel Architecture Labs; http://www.intel.com/IAL/powermgm.html; Intel Architecture Labs: 800-253-3696). Charger functionality complies with the Intel/Duracell Smart Charger Specification for a level 2 charger. The MAX1647 uses the SMBus Read-Word and WriteWord protocols to communicate with the battery it is charging, as well as with any host system that monitors the battery to charger communications. The MAX1647 never initiates communication on the bus; it only receives commands and responds to queries for status information. Figure 7 shows examples of the SMBus Write-Word and Read-Word protocols. 16 ACK ACK SCL The MAX1647 uses an internal low-dropout linear regulator to create a 5.4V power supply (VL), which powers its internal circuitry. VL can supply up to 20mA. A portion of this current powers the internal circuitry, but the remaining current can power the external circuitry. The current used to drive the MOSFETs comes from this supply, which must be considered when calculating how much power can be drawn. To estimate the current required to drive the MOSFETs, multiply the total gate charge of each MOSFET by the switching frequency (typically 250kHz). The internal circuitry requires as much as 6mA from the VL supply. To ensure VL stability, bypass the VL pin with a 1µF or greater capacitor. The MAX1647 has an internal ±2% accurate 3.9V reference voltage. An external reference can be used to increase the charger’s accuracy. Use a 4.096V reference, such as the MAX874, for compliance with the Intel/ Duracell smart-battery specification. Voltage-setting accuracy is ±0.65%, so the total voltage accuracy is the accuracy added to the reference accuracy. For 1% total voltage accuracy, use a reference with ±0.35% or greater accuracy. If the internal reference is used, bypass it with a 0.1µF or greater capacitor. TIME MAX1647/MAX1648 Chemistry-Independent Battery Chargers Chemistry-Independent Battery Chargers ChargingVoltage( ) The ChargingVoltage( ) command uses Write-Word protocol. The command code for ChargingVoltage( ) is 0x15; thus, the CMD7–CMD0 bits in Write-Word protocol should be 0b00010101. The 16-bit binary number formed by D15–D0 represents the voltage set point (V0) in millivolts; however, since the MAX1647 has only 16mV resolution in setting V0, the D0, D1, D2, and D3 bits are ignored. For D15 = D14 = 0: ChargerMode( ) The ChargerMode( ) command uses Write-Word protocol. The command code for ChargerMode( ) is 0x12; thus the CMD7–CMD0 bits in Write-Word protocol should be 0b00010010. Table 2 describes the functions of the 16 different data bits (D0–D15). Bit 0 refers to the D0 bit in the Write-Word protocol (Figure 7). VOLTAGE_OR = 0 and V0 in Volts = 4 x REF x Whenever the BATTERY_PRESENT status bit is clear, the HOT_STOP bit is set, regardless of any previous ChargerMode( ) command. To charge a battery that has a thermistor impedance in the HOT range (i.e., THERMISTOR_HOT = 1 and THERMISTOR_UR = 0), the host must use the ChargerMode( ) command to clear HOT_STOP after the battery is inserted. The HOT_STOP bit returns to its default power-up condition (‘1’) whenever the battery is removed. ( ) VDAC 210 In equation 1, VDAC is the decimal equivalent of the binary number represented by bits D13, D12, D11, D10, D9, D8, D7, D6, D5, and D4 programmed with the ChargingVoltage( ) command. For example, if D4–D13 are all set, VDAC is the decimal equivalent of 0b1111111111 (1023). If either D15 or D14, or both D15 and D14, are set, all the bits in the voltage DAC (Figure 6a) are set, regardless of D13–D0, and the status register’s VOLTAGE_OR bit is set. For D15 = 1 and/or D14 = 1: ( ) VOLTAGE_OR = 1 and V0 in Volts = 4 x REF x 210 - 1 210 Table 2. ChargerMode( ) Bit Functions BIT POSITION* POR VALUE** INHIBIT_CHARGE 0 0 0 = Allow normal operation; clear the CHG_INHIBITED status bit. 1 = Turn the charger off; set the CHG_INHIBITED status bit. ENABLE_POLLING 1 — Not implemented. Write 0 into this bit. POR_RESET 2 — 0 = No change in any non-ChargerMode( ) settings. 1 = Change the voltage and current settings to 0xFFFF and 0x00C0 respectively; clear the THERMISTOR_HOT and ALARM_INHIBITED bits. RESET_TO_ZERO 3 — Not implemented. Write 0 into this bit. 4, 7, 8, 9, 11–15 — Not implemented. Write 1 into this bit. BATTERY_PRESENT_MASK 5 0 0 = Interrupt on either edge of the BATTERY_PRESENT status bit. 1 = Do not interrupt because of a BATTERY_PRESENT bit change. POWER_FAIL_MASK 6 1 0 = Interrupt on either edge of the POWER_FAIL status bit. 1 = Do not interrupt because of a POWER_FAIL bit change. HOT_STOP 10 1 0 = The THERMISTOR_HOT status bit does not turn the charger off. 1 = THERMISTOR_HOT turns the charger off. BIT NAME N/A *Bit position in the D15–D0 data. N/A = Not available. FUNCTION **Power-on reset value. ______________________________________________________________________________________ 17 MAX1647/MAX1648 Each communication with the MAX1647 begins with a start condition that is defined as a falling edge on SDA with SCL high. The device address follows the start condition. The MAX1647 device address is 0b0001001 (0b indicates a binary number), which may also be denoted as 0x12 (0x indicates a hexadecimal number) for Write-Word commands, or 0x13 in hexadecimal for Read-Word commands (note that the address is only seven bits, and the hexadecimal representation uses R/W as its least significant bit). Figure 8 shows the mapping between V0 (the voltageregulation-loop set point) and the ChargingVoltage( ) data. The power-on reset value for the ChargingVoltage( ) register is 0xFFF0; thus, the first time a MAX1647 is powered on, the BATT voltage regulates to 16.368V with VREF = 4.096V. Any time the BATTERY_PRESENT status bit is clear, the ChargingVoltage( ) register returns to its power-on reset state. ChargingCurrent( ) The ChargingCurrent( ) command uses Write-Word protocol. The command code for ChargingCurrent( ) is 0x14; thus, the CMD7–CMD0 bits in Write-Word protocol should be 0b00010100. The 16-bit binary number formed by D15–D0 represents the current-limit set point (I0) in milliamps. Tying SEL to AGND selects a 1.023A maximum setting for I0. Leaving SEL open selects a 2.047A maximum setting for I0. Tying SEL to VL selects a 4.095A maximum setting for I0. 16.368 VREF = 4.096V 12.592 VOLTAGE SET POINT (V0) MAX1647/MAX1648 Chemistry-Independent Battery Chargers 8.400 4.192 0 0b000000000000xxxx 0x000x 0b000100000110xxxx 0x106x 0b001000001101xxxx 0x20Dx 0b001100010011xxxx 0x313x 0b001111111111xxxx 0x3FFx 0b111111111111xxxx 0xFFFx ChargingVoltage( ) D15–D0 DATA Figure 8. ChargingVoltage( ) Data to Voltage Mapping 18 ______________________________________________________________________________________ Chemistry-Independent Battery Chargers ChargingCurrent( ) command and IOUT source current. The CCV_LOW comparator checks to see if the output voltage is too high by comparing CCV to REF / 4. If CCV_LOW = 1 (when CCV < REF / 4), IOUT shuts off, preventing the output voltage from exceeding the voltage set point specified by the ChargingVoltage( ) register. VOLTAGE_NOTREG = 1 whenever the internal clamp pulls down on CCV. (The internal clamp pulls down on CCV to keep its voltage close to CCI’s voltage.) Table 3. Relationship Between IOUT Source Current and ChargingCurrent( ) Value CHARGE_ INHIBITED (NOTE 1) ALARM_ INHIBITED ChargingVoltage( ) ChargingCurrent( ) CCV_LOW VOLTAGE_ NOTREG IOUT OUTPUT CURRENT 0 0 0 0x0010–0xFFFF 0x0001–0x001F 0 x 1mA–31mA 0 0 0 0x0010–0xFFFF 0x0001–0x001F 1 0 0mA 0 0 0 0x0010–0xFFFF 0x0001–0x001F 1 1 1mA–31mA 0 0 0 0x0010–0xFFFF 0x0020–0xFFFF 0 x 31mA 0 0 0 0x0010–0xFFFF 0x0020–0xFFFF 1 0 0mA 0 0 0 0x0010–0xFFFF 0x0020–0xFFFF 1 1 31mA 0 0 0 x 0x0000 x x 0mA 0 0 0 0x0000–0x000F x x x 0mA 0 x 1 x x x x 0mA 0 1 x x x x x 0mA 1 x x x x x x 0mA Note 1: Logical AND of THERMISTOR_HOT, HOT_STOP, NOT(THERMISTOR_UR). 185 AVERAGE CS - BATT VOLTAGE IN CURRENT REGULATION (mV) SEL = OPEN OR SEL = VL 94 2.94 0b000001 0b100000 0b111111 CURRENT DAC CODE, DA5–DA0 BITS Figure 9. Average Voltage Between CS and BATT vs. Current DAC Code ______________________________________________________________________________________ 19 MAX1647/MAX1648 Two sources of current in the MAX1647 charge the battery: a binary-weighted linear current source sources from IOUT, and a switching regulator controls the current flowing through the current-sense resistor (R1). IOUT provides a small maintenance charge current to compensate for battery self-discharge, while the switching regulator provides large currents for fast charging. IOUT sources from 1mA to 31mA. Table 3 shows the relationship between the value programmed with the MAX1647/MAX1648 Chemistry-Independent Battery Chargers Table 4. Relationship Between Current DAC Code and the ChargingCurrent( ) Value CHARGE_ INHIBITED (NOTE 1) ALARM_ INHIBITED ChargingVoltage( ) SEL ChargingCurrent( ) CURRENT DAC CODE 0 0 0 0x0010–0xFFFF 0V 0x0001–0x001F 0 0 0 0x0010–0xFFFF 0V 0x0020–0x003F 0 0 0 0x0010–0xFFFF 0V 0 0 0 0x0010–0xFFFF 0 0 0 0 0 0 0 0 SW REG ON? (NOTE 2) 0 No 0 2 Yes 0 0x0040–0x03DF 4–60 Yes 0 0V 0x03E0–0x03FF 62 Yes 0 0x0010–0xFFFF 0V 0x0400–0xFFFF 62 Yes 1 0 0x0010–0xFFFF open 0x0001–0x001F 0 No 0 0 0x0010–0xFFFF open 0x0020–0x003F 1 Yes 0 0 0 0x0010–0xFFFF open 0x0040–0x07DF 2–62 Yes 0 0 0 0 0x0010–0xFFFF open 0x07E0–0x07FF 63 Yes 0 0 0 0 0x0010–0xFFFF open 0x0800–0xFFFF 63 Yes 1 0 0 0 0x0010–0xFFFF VL 0x0001–0x001F 0 No 0 0 0 0 0x0010–0xFFFF VL 0x0020–0x003F 1 Yes 0 0 0 0 0x0010–0xFFFF VL 0x0040–0x007F 1 Yes 0 0 0 0 0x0010–0xFFFF VL 0x0080–0x0F9F 2–62 Yes 0 0 0 0 0x0010–0xFFFF VL 0x0FA0–0x0FBF 63 Yes 0 0 0 0 0x0010–0xFFFF VL 0x0FC0–0x0FFF 63 Yes 0 0 0 0 0x0010–0xFFFF VL 0x0001–0xFFFF 63 Yes 1 0 0 0 x x 0x0000 0 No 0 0 0 0 0x0010–0xFFFF x x N/C No N/C 0 x 1 x x x N/C No N/C 0 1 x x x x N/C No N/C 1 x x x x x N/C No N/C Note 1: Logical AND of THERMISTOR_HOT, HOT_STOP, NOT(THERMISTOR_UR). Note 2: Value of CURRENT_OR bit in the ChargerStatus( ) register. N/C = No change. Table 5. Effect of SEL Pin-Strapping on the ChargingCurrent( ) Data Bits SEL R1 (mΩ) D15 D14 D13 D12 D11 AGND 181 0 0 0 0 Open 90 0 0 0 0 VL 45 0 0 0 0 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 0 0 DA5 DA4 DA3 DA2 DA1 I4 I3 I2 I1 I0 0 DA5 DA4 DA3 DA2 DA1 DA0 I4 I3 I2 I1 I0 DA5 DA4 DA3 DA2 DA1 DA0 * I4 I3 I2 I1 I0 *When SEL = VL, D5 = 1 forces DA0 to be 1 regardless of the D6 bit value. With the switching regulator on, the current through R1 (Figure 3) is regulated by sensing the average voltage between CS and BATT. A 6-bit current DAC controls the current-limit set point. DA5–DA0 denote the bits in the current DAC code. Figure 9 shows the relationship between the current DAC code and the average voltage between CS and BATT. 20 When the switching regulator is off, DHI is forced to LX and DLO is forced to ground. This prevents current from flowing through inductor L1. Table 4 shows the relationship between the ChargingCurrent( ) register value and the switching regulator current DAC code. ______________________________________________________________________________________ Chemistry-Independent Battery Chargers The power-on reset value for the ChargingCurrent( ) register is 0x000C. Irrespective of the SEL pin setting, the MAX1647 powers on with I0 set to 12mA (i.e., DA5–DA0, I1, and I0 all equal to zero, and only I3 and I2 set). Anytime the BATTERY_PRESENT status bit is clear (battery removed), the ChargingCurrent( ) register returns to its power-on reset state. This ensures that upon insertion of a battery, the initial charging current is 12mA. AlarmWarning( ) The AlarmWarning( ) command uses Write-Word protocol. The command code for AlarmWarning( ) is 0x16; thus the CMD7–CMD0 in Write-Word protocol should be 0b00010110. The AlarmWarning( ) command sets the ALARM_INHIBITED status bit in the MAX1647 if D15, D14, or D12 of the Write-Word protocol data equals 1. Table 6 summarizes the AlarmWarning( ) command’s function. The ALARM_INHIBITED status bit remains set until BATTERY_PRESENT = 0 (battery removed) or a ChargerMode() command is written with the POR_RESET bit set. As long as ALARM_INHIBITED = 1, the MAX1647 switching regulator and IOUT current source remain off. ChargerStatus( ) The ChargerStatus( ) command uses Read-Word protocol. The command code for ChargerStatus( ) is 0x13; thus, the CMD7–CMD0 bits in Write-Word protocol should be 0b00010011. The ChargerStatus( ) command returns information about thermistor impedance and the MAX1647’s internal state. The Read-Word protocol returns D15–D0 (Figure 7). Table 7 describes the meaning of the individual bits. The latched bits, THERMISTOR_HOT and ALARM_INHIBITED, are cleared whenever BATTERY_PRESENT = 0 or ChargerMode( ) is written with POR_RESET = 1. Interrupts and the Alert-Response Address An interrupt is triggered (INT goes low) whenever power is applied to DCIN, the BATTERY_PRESENT bit changes, or the POWER_FAIL bit changes. BATTERY_PRESENT and POWER_FAIL have interrupt masks that can be set or cleared via the ChargerMode( ) command. INT stays low until the interrupt is cleared. There are two methods for clearing the interrupt: issuing a ChargerStatus( ) command, and using the Receive Byte protocol with a 0x19 Alert-Response address. The MAX1647 responds to the Alert-Response address with the 0x89 byte. __________Applications Information Using the MAX1647 with Duracell Smart Batteries The following pseudo-code describes an interrupt routine that is triggered by the MAX1647 INT output going low. This interrupt routine keeps the host informed of any changes in battery-charger status, such as DCIN power detection, or battery removal and insertion. DOMAX1647: { This is the beginning of the routine that handles MAX1647 interrupts. } { Check the status of the MAX1647. } TEMPWORD = ReadWord( SMBADDR = 0b00010011 = 0x13, COMMAND = 0x13 ) { Check for the normal power-up case without a battery installed. THERMISTOR_OR = 1, BATTERY_PRESENT = 0. Use 0b1011111011111111 = 0xBEFF as the mask. } IF (TEMPWORD OR 0xBEFF) = 0xBFFF THEN GOTO NOBATT: { Check to see if the battery is installed. BATTERY_ PRESENT = 1. Use 0b1011111111111111 = 0xBFFF as the mask. } Table 6. Effect of the AlarmWarning( ) Command AlarmWarning( ) WRITE-WORD PROTOCOL DATA D15 D14 D13 D12 D11 1 x x x 1 x x D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 RESULT x x x x x x x x x x x x x Set ALARM_INHIBITED x x x x x x x x x x x x x x Set ALARM_INHIBITED x 1 x x x x x x x x x x x x Set ALARM_INHIBITED ______________________________________________________________________________________ 21 MAX1647/MAX1648 With SEL = AGND, R1 should be as close as possible to 0.185 / 1.023 = 181mΩ to ensure that the actual output current matches the data value programmed with the ChargingCurrent( ) command. With SEL = open, R1 should be as close as possible to 90mΩ. With SEL = VL, R1 should be as close as possible to 45mΩ. Table 5 summarizes how SEL affects the R1 value and the meaning of data bits D15–D0 in the ChargingCurrent( ) command. DA5–DA0 denote the current DAC code bits, and I4–I0 denote the IOUT linear-current source binary weighting bits. Note that whenever any current DAC bits are set, the linear-current source is set to full scale (31mA). MAX1647/MAX1648 Chemistry-Independent Battery Chargers IF (TEMPWORD OR 0xBEFF) = 0xFFFF THEN GOTO HAVEBATT: GOTO ENDINT: HAVEBATT: { A battery is installed. Turn the battery’s broadcast mode off to monitor the charging process. Using the BatteryMode( ) command, make sure the CHARGER_ MODE bit is set. } WriteWord(SMBADDR = 0b00010110 = 0x16, COMMAND = 0X03, DATA = 0x4000) GOTO ENDINT: NOBATT: { Notify the system that AC power is present, but no battery is present. } GOTO ENDINT: ENDINT: { This is the end of the interrupt routine. } The following pseudo-code describes a polling routine that queries the battery for its desired charge voltage and charge current, checks to make sure that the requested charge current and charge voltage are valid, and instructs the MAX1647 to comply with the request. DOPOLLING: { This is the beginning of the polling routine. } { Ask the battery what voltage it wants using the battery’s ChargingVoltage( ) command. } TEMPVOLTAGE = ReadWord( SMBADDR = 0b00010111 = 0x17, COMMAND = 0x15 ) { Ask the battery what current it wants using the battery’s ChargingCurrent( ) command. } TEMPCURRENT = ReadWord( SMBADDR = 0b00010111 = 0x17, COMMAND = 0x14 ) { Now the routine can check that the TEMPVOLTAGE and TEMPCURRENT values make sense and that the battery is not malfunctioning. } { With valid TEMPVOLTAGE and TEMPCURRENT values, instruct the MAX1647 to comply with the request. } WriteWord( SMBADDR = 0b00010010 = 0x12 , COMMAND = 0x15, DATA = TEMPVOLTAGE ) WriteWord( SMBADDR = 0b00010010 = 0x12 , COMMAND = 0x14, DATA = TEMPCURRENT ) ENDPOL: { This is the end of the polling routine. } 22 Negative Input Voltage Protection In most portable equipment, the DC power to charge batteries enters via a two-conductor cylindrical power jack. It is easy for the end user to add an adapter to switch the DC power’s polarity. Polarized capacitor C6 would be destroyed if a negative voltage were applied. Diode D4 in Figure 3 prevents this from happening. If reverse-polarity protection for the DC input power is not necessary, diode D4 can be omitted. This eliminates the power lost due to the voltage drop on diode D4. Selecting External Components for the MAX1647 4A Application The MAX1647 can be configured to charge at a maximum current of 4A (instead of 2A, as shown in Figure 3) by changing the external power components and tying SEL to REF. The following paragraphs discuss the selection requirements for each component in Figure 3 that must be changed to accommodate the 4A application. Diode D4 in Figure 3 has to support both the charge current and the current required to operate the host load (i.e., what the batteries normally power when not charging). This means that the continuous current flowing through D4 exceeds 4A. One possible choice for D4 is the Motorola MBRD835L 8A Schottky barrier diode in a DPAK surface-mount package. Care must be taken in thermal management of the circuit board when using the 4A application circuit, by mounting D4 on a three-square-inch piece of copper. Motorola’s MBRD835L can also be used for D3. The Siliconix Si4410DY is a good choice for M1 and M2 in the 4A application. Changing M2 from a 2N7002 (Table 1) to a Si4410DY increases the power dissipated by the MAX1647’s 20-pin SSOP. High-current inductors are difficult to find in surface-mount packages. Low-cost solutions use toroidal powdered-iron cores with exposed windings of heavy-gauge wire. The Coiltronics CTX20-5-52 20µH 5A inductor provides a highefficiency solution. R1A must also dissipate more power in the 4A application circuit than in the circuit of Figure 3. R1A’s value decreases to 50mΩ in the 4A application. IRC’s LR2512-01-R050-F meets this requirement with a 1W maximum power-dissipation rating. ______________________________________________________________________________________ Chemistry-Independent Battery Chargers MAX1647/MAX1648 Table 7. ChargerStatus( ) Bit Descriptions NAME BIT POSITION LATCHED? CHARGE_INHIBITED 0 Yes 0 = Ready to charge a smart battery 1 = Charger is off; IOUT current = 0mA; DLO = PGND; DHI = LX MASTER_MODE 1 N/A Always returns ‘0’ VOLTAGE_NOTREG 2 No 0 = BATT voltage is limited at the voltage set point (BATT = V0). 1 = BATT voltage is less than the voltage set point (BATT < V0). CURRENT_NOTREG 3 No 0 = Current through R1 is at its limit (IBATT = I0). 1 = Current through R1 is less than its limit (IBATT < I0). LEVEL_2 4 N/A Always returns 1 LEVEL_3 5 N/A Always returns 0 CURRENT_OR 6 No 0 = ChargingCurrent( ) value is valid for MAX1647. 1 = ChargingCurrent( ) value exceeds what MAX1647 can actually deliver. VOLTAGE_OR 7 No 0 = ChargingVoltage( ) value is valid for MAX1647. 1 = ChargingVoltage( ) value exceeds what MAX1647 can actually deliver. THERMISTOR_OR 8 No 0 = THM voltage < 91% of REF voltage 1 = THM voltage > 91% of REF voltage THERMISTOR_COLD 9 No 0 = THM voltage < 75% of REF voltage 1 = THM voltage > 75% of REF voltage DESCRIPTION THERMISTOR_HOT 10 Yes This bit reports the state of an internal SR flip-flop (denoted THERMISTOR_HOT flip-flop). The THERMISTOR_HOT flip-flop is set whenever THM is below 23% of REF. It is cleared whenever BATTERY_PRESENT = 0 or ChargerMode( ) is written with POR_RESET = 1. THERMISTOR_UR 11 No 0 = THM voltage > 5% of REF voltage 1 = THM voltage < 5% of REF voltage ALARM_INHIBITED 12 Yes This bit reports the state of an internal SR flip-flop (denoted ALARM_INHIBITED flip-flop). The ALARM_INHIBITED flip-flop is set whenever the AlarmWarning( ) command is written with D15, D14, or D12 set. The ALARM_INHIBITED flip-flop is cleared whenever BATTERY_PRESENT = 0 or ChargerMode( ) is written with POR_RESET = 1. POWER_FAIL 13 No 0 = BATT voltage < 89% of DCIN voltage 1 = BATT voltage > 89% of DCIN voltage BATTERY_PRESENT 14 No 0 = No battery is present (THERMISTOR_OR = 1). 1 = A battery is present (THERMISTOR_OR = 0). AC_PRESENT 15 No 0 = VL voltage < 4V 1 = VL voltage > 4V *Bit position in the D15-D0 data. N/A = Not applicable. ___________________Chip Information TRANSISTOR COUNT: 3612 SUBSTRATE CONNECTED TO AGND ______________________________________________________________________________________ 23 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.) 2 SSOP.EPS MAX1647/MAX1648 Chemistry-Independent Battery Chargers 1 INCHES E H MILLIMETERS DIM MIN MAX MIN MAX A 0.068 0.078 1.73 1.99 A1 0.002 0.008 0.05 0.21 B 0.010 0.015 0.25 0.38 C D 0.20 0.09 0.004 0.008 SEE VARIATIONS E 0.205 e 0.212 0.0256 BSC 5.20 INCHES D D D D D 5.38 MILLIMETERS MIN MAX MIN MAX 0.239 0.239 0.278 0.249 0.249 0.289 6.07 6.07 7.07 6.33 6.33 7.33 0.317 0.397 0.328 0.407 8.07 10.07 8.33 10.33 N 14L 16L 20L 24L 28L 0.65 BSC H 0.301 0.311 7.65 7.90 L 0.025 0∞ 0.037 8∞ 0.63 0∞ 0.95 8∞ N A C B e A1 L D NOTES: 1. D&E DO NOT INCLUDE MOLD FLASH. 2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006"). 3. CONTROLLING DIMENSION: MILLIMETERS. 4. MEETS JEDEC MO150. 5. LEADS TO BE COPLANAR WITHIN 0.10 MM. PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, SSOP, 5.3 MM APPROVAL DOCUMENT CONTROL NO. 21-0056 24 ______________________________________________________________________________________ REV. C 1 1 Chemistry-Independent Battery Chargers N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS DIM A A1 B C e E H L 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D C A B e 0∞-8∞ A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 REV. B 1 1 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 ____________________25 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX1647/MAX1648 Package Information (continued) (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.)