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19-1796; Rev 1; 1/03
KIT ATION EVALU ABLE AVAIL
Power Source Selector for Dual-Battery Systems
Features
o Patented 7-MOSFET Solution o Automatically Detects and Responds to: Low Battery Voltage Condition Battery Insertion and Removal AC Adapter Presence o Direct Drive of P-Channel MOSFETs o Simplifies Power Management P Firmware o Extends Battery Life by Allowing Power Management P to Enter Standby o 4.75V to 28V AC Adapter Input Voltage Range o Integrated LDO with 1mA Drive Capability o Small Footprint 20-Pin TSSOP Package Topology Offers Low-Cost
General Description
The MAX1773/MAX1773A highly integrated ICs serve as the control logic for a system with multiple power sources. They directly drive external P-channel MOSFETs to select from an AC adapter and dual battery sources for charge and discharge. The selection is made based on the presence of the power sources and the state of the batteries. The MAX1773/MAX1773A detect low battery conditions using integrated analog comparators and check for the presence of a battery by using battery thermistor outputs. The MAX1773/MAX1773A are designed for use with a buck topology charger. They provide a simple and easily controlled solution to a difficult analog power control problem. The MAX1773/MAX1773A provide most of the power source monitoring and selection, freeing the system power management microprocessor (P) for other tasks. This not only simplifies development of the power management firmware for the P but also allows the P to enter standby, thereby reducing system power consumption. The MAX1773A is recommended for new designs.
MAX1773/MAX1773A
Ordering Information
PART MAX1773EUP MAX1773AEUP TEMP. RANGE -40C to +85C -40C to +85C PIN-PACKAGE 20 TSSOP 20 TSSOP
________________________Applications
Notebook and Subnotebook Computers PDAs and Handy-Terminals Internet Tablets Dual-Battery Portable Equipment
Pin Configuration appears at end of data sheet.
Covered by U.S. Patent number 5,764,032.
Typical Operating Circuit
FROM HOST P BATSEL VDD MINV 3.3V
SYSTEM LOGIC SUPPLY
TO HOST P AC ADAPTER INPUT
ACPRES BATSTAT ACDET PDS
3.3V
MAX1773 MAX1773A
EXTLD THMA BATA TCOMP THMB BATB COMB DISB CHGB BATTERY B
BATTERY A
COMA DISA CHGA
STEP-DOWN CHARGER OUTPUT INPUT
OUTPUT 3.3V DC-DC CONVERTER INPUT
SYSTEM LOAD
________________________________________________________________ Maxim Integrated Products
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
ABSOLUTE MAXIMUM RATINGS
VBATA, VBATB to GND ............................................-0.3V to +20V VCOMA to GND........................................-0.3V to (VBATA + 0.3V) VCOMB to GND........................................-0.3V to (VBATB + 0.3V) VCHGA, VCHGB, VEXTLD, VACDET to GND ..............-0.3V to +30V VPDS, VDISA, VDISB to GND ...................-0.3V to (VEXTLD + 0.3V) VDD, VBATSEL, V ACPRES, VBATSTAT, VTCOMP, VMINV to GND.......................................................-0.3V to +6V VTHMA, VTHMB (Note 1)............................................ -0.3V to +6V Continuous Current out of THMA, THMB............................20mA I ACPRES, IBATSTAT Sink Current..........................................30mA Continuous Power Dissipation (TA = +70C) 20-Pin TSSOP (derate 7.0mW/C above +70C) ........560mW Operating Temperature ......................................-40C to +85C Storage Temperature ........................................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Note 1: Signals on THMA and THMB below -0.3V are clamped by internal diodes limit forward diode current to maximum continuous current. When voltage on these pins is below -0.3V.
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
(VBATA = VBATB = 16.8V, CVDD = 3.3F, VMINV = 0.93V, VEXTLD = VACDET = 28V, VTCOMP = 3V, VTHMA = VTHMB = 1.65V, VBATSEL = 0, CCOMA = CCOMB = CDISA = CDISB = CCHGA = CCHGB = CPDS = 5nF, TA = 0C to +85C, unless otherwise noted.)
PARAMETER EXTLD Supply Voltage Range BATA, BATB Supply Voltage Range BATA, BATB Quiescent Current (Current from the higher voltage supply) VBATA = 4.75V to 19V, VBATB = 4.75V to 19V, IVDD = 0 VBATA = 4.75V to 19V, VBATB = 4.75V to 19V, IVDD = 0 VACDET = 28V VACDET = 2.2V to VBATA and VBATB VACDET = 28V VACDET = 2.2V to VBATA and VBATB CONDITIONS VEXTLD > VBATA and VBATB MIN 4.75 4.75 5 40 5 8 35 5 TYP MAX 28.00 19.00 8 70 8 13 55 8 A A A UNITS V V
BATA, BATB Quiescent Current (Current from the lower voltage supply)
VACDET = 28V, VEXTLD = 28V EXTLD Quiescent Current LINEAR REGULATOR VDD Output Voltage IVDD = 0 to 100A IVDD = 100A to 1mA VBATA or VBATB = 5V to 19V, VEXTLD = 5V VDD Power-Supply Rejection Ratio VBATA = VBATB = 5V, VEXTLD = 5V to 28V VBATA, VBATB, or VEXTLD = 5V to 19V, sawtooth at 10V/s, other supplies = 12V Hysteresis is typically 50mV (Note 2) VTHM_ = 5.5V VTHMA = VTHMB = 0 to 5.5V TCOMP Input Voltage Range VTHMA = VTHMB = 0 to 5.5V, VBATA = VBATB = VEXTLD = 4.75V 0 0 2.0 0 0 3.234 3.168 VACDET= 2.2V to VBATA and VBATB, VEXTLD = 16V
3.3 3.3
3.367 3.432 1.0 1.0
V
mV/V
1 2.5 3.0 1.1 5.5 0.1 100 5.5 4.3 V V V V nA
VDD Undervoltage Lockout COMPARATORS TCOMP Undervoltage Lockout THM_ Input Voltage Range THM_ Input Leakage Current
2
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
ELECTRICAL CHARACTERISTICS (continued)
(VBATA = VBATB = 16.8V, CVDD = 3.3F, VMINV = 0.93V, VEXTLD = VACDET = 28V, VTCOMP = 3V, VTHMA = VTHMB = 1.65V, VBATSEL = 0, CCOMA = CCOMB = CDISA = CDISB = CCHGA = CCHGB = CPDS = 5nF, TA = 0C to +85C, unless otherwise noted.)
PARAMETER TCOMP Input Leakage Current THM_ to TCOMP Trip Threshold THM_ to TCOMP Hysteresis ACDET Operating Voltage Range ACDET Logic Threshold High VACDET = 3V, VACDET < VBATA and VBATB ACDET Input Bias Current ACDET to BATA Trip Threshold ACDET to BATA Hysteresis ACDET to BATB Trip Threshold ACDET to BATB Hysteresis MINV Operating Voltage Range MINV Input Bias Current BAT_ Minimum Voltage Trip Threshold BATSEL Input Low Voltage BATSEL Input High Voltage BATSEL Input Leakage Current BATSEL Action Delay GATE DRIVERS COM_ Initial Source Current COM_ Final Source Current COM_ Sink Current (PMOS Turn-On) COM_ Turn-On Clamp Voltage (VCOM_ to VBAT_) PDS Source Current (PMOS Turn-Off) PDS Sink Current (PMOS Turn-On) PDS Leakage Current (PMOS Off) CHG_ Sink Current (PMOS Turn-On) CHG_ Leakage Current (PMOS Off) DIS_ Initial Source Current DIS_ Final Source Current DIS_ Sink Current (PMOS Turn-On) VBAT_ = 16.8V, VCOM_ = 14.8V VBAT_ = 16.8V, VCOM_ = 16.4V VBAT_ = 16.8V, VCOM_ = 14.8V VCOM_ = 11.8V, VBAT_ = 16.8V (Note 4) VBAT_ = 8V to 19V VBAT_ = 4.75V to 8V VPDS = 10V, VEXTLD = 12V VPDS = 2V to 28V VPDS = 28V VCHG_ = 2V to 22V VCHG_ = 28V VEXTLD = 15V, VDIS_ = 13V VEXTLD = 15V, VDIS_ = 14.6V VEXTLD = 15V, VDIS_ = 13V VEXTLD = 16.8V, VDIS_ = 11.8V (Note 5) 5 10 50 4 100 150 0.7 5 10 50 4 -11.5 -8.00 5 0.8 1.0 0.1 1.0 0.1 1.2 2 1.3 2 -9.5 -7.5 -4.25 100 150 mA A mA V mA mA A mA A mA A mA VBATSEL = 5.5V 20 VBATA = VBATB = 5 x VMINV VMINV = 0.93V to 2.6V VBAT_ falling VMINV = 0.93V VMINV = 2.6V VACDET falling with respect to VBATB VACDET = 3V, VACDET < VBATB, VBATA = 0 VACDET = 28V, VACDET > VBATA and VBATB VACDET falling with respect to VBATA 0 100 0 100 0.93 -100 4.55 12.7 2.0 1 100 4.65 13 (Note 3) VTCOMP = 5.5V THM_ falling with respect to TCOMP -30 15 2.2 2.2 4 5 6 50 150 50 150 8 9 11 100 200 100 200 2.60 +100 4.75 13.3 0.8 mV mV mV mV V nA V V V A s A 50 28.0 CONDITIONS MIN TYP 0.1 MAX 100 +30 UNITS nA mV mV V V
Typical hysteresis is 100mV
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
ELECTRICAL CHARACTERISTICS (continued)
(VBATA = VBATB = 16.8V, CVDD = 3.3F, VMINV = 0.93V, VEXTLD = VACDET = 28V, VTCOMP = 3V, VTHMA = VTHMB = 1.65V, VBATSEL = 0, CCOMA = CCOMB = CDISA = CDISB = CCHGA = CCHGB = CPDS = 5nF, TA = 0C to +85C, unless otherwise noted.)
PARAMETER DIS_ Turn-On Clamp Voltage (VDIS_ to VEXTLD) STATUS OUTPUTS ACPRES Sink Current BATSTAT Sink Current ACPRES Leakage Current BATSTAT Leakage Current TRANSITION TIMES Battery Switchover Delay Battery Action Delay Thermistor Action Delay AC to Battery Switchover Delay Battery to AC Switchover Delay CHG_ Turn-On Delay VACDET = 2.2V, VMINV = 0.93V (Note 6) VACDET = 2.2V, VMINV = 0.93V (Note 7) VACDET = 2.2V, VMINV = 0.93V (Note 8) VACDET = 2.2V, VMINV = 0.93V (Note 9) VACDET = 2.2V, VMINV = 0.93V (Note 10) (Note 11) 130 300 5 260 12 10 260 530 s s s s s s V ACPRES = 0.4V V ACPRES = 5.5V VBATSTAT = 0.4V VBATSTAT = 5.5V V ACPRES = 5.5V VBATSTAT = 5.5V 1 0.1 0.1 1 1 1 30 mA mA A A CONDITIONS VEXTLD = 8V to 28V VEXTLD = 4.75V to 8V MIN -11.5 -8.00 TYP -9.5 MAX -7.5 -4.25 UNITS V
ELECTRICAL CHARACTERISTICS
(VBATA = VBATB = 16.8V, CVDD = 3.3F, VMINV = 0.93V, VEXTLD = VACDET = 28V, VTCOMP = 3V, VTHMA = VTHMB = 1.65V, VBATSEL = 0, CCOMA = CCOMB = CDISA = CDISB = CCHGA = CCHGB = CPDS = 5nF, TA = -40C to +85C, unless otherwise noted.)
PARAMETER EXTLD Supply Voltage Range BATA, BATB Supply Voltage Range BATA, BATB Quiescent Current (Current from the higher voltage supply) VBATA = 4.75V to 19V, VACDET = 28V VBATB = 4.75V to 19V, VACDET = 2.2V to IVDD = 0 VBATA and VBATB VBATA = 4.75V to 19V, VACDET = 28V VBATB = 4.75V to 19V, VACDET = 2.2V to IVDD = 0 VBATA and VBATB VACDET = 28V, VEXTLD = 28V VACDET = 2.2V to VBATA and VBATB, VEXTLD = 16V IVDD = 0 to 100A IVDD = 100A to 1mA VBATA or VBATB = 5V to 19V, VEXTLD = 5V VBATA = VBATB = 5V, VEXTLD = 5V to 28V Hysteresis is typically 50mV (Note 2) 2.0 0 3.234 3.168 CONDITIONS VEXTLD > VBATA and VBATB MIN 4.75 4.75 TYP MAX 28.00 19.00 8 70 8 13 55 8 3.367 3.432 1.0 1.0 3.0 1.1 A A UNITS V V
BATA, BATB Quiescent Current (Current from the lower voltage supply) EXTLD Quiescent Current LINEAR REGULATOR VDD Output Voltage VDD Power-Supply Rejection Ratio VDD Undervoltage Lockout COMPARATORS TCOMP Undervoltage Lockout
A
V mV/V V V
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Power Source Selector for Dual-Battery Systems
ELECTRICAL CHARACTERISTICS (continued)
(VBATA = VBATB = 16.8V, CVDD = 3.3F, VMINV = 0.93V, VEXTLD = VACDET = 28V, VTCOMP = 3V, VTHMA = VTHMB = 1.65V, VBATSEL = 0, CCOMA = CCOMB = CDISA = CDISB = CCHGA = CCHGB = CPDS = 5nF, TA = -40C to +85C, unless otherwise noted.)
PARAMETER THM_ Input Voltage Range THM_ Input Leakage Current TCOMP Input Voltage Range ACDET Operating Voltage Range ACDET Logic Threshold High VACDET = 3V, VACDET < VBATA and VBATB ACDET Input Bias Current ACDET to BATA Trip Threshold ACDET to BATA Hysteresis ACDET to BATB Trip Threshold ACDET to BATB Hysteresis MINV Operating Voltage Range MINV Input Bias Current BAT_ Minimum Voltage Trip Threshold BATSEL Input Low Voltage BATSEL Input High Voltage BATSEL Input Leakage Current BATSEL Action Delay GATE DRIVERS COM_ Initial Source Current COM_ Final Source Current COM_ Sink Current (PMOS Turn-On) COM_ Turn-On Clamp Voltage (VCOM_ to VBAT_) PDS Source Current (PMOS Turn-Off) PDS Sink Current (PMOS Turn-On) PDS Leakage Current (PMOS Off) CHG_ Sink Current (PMOS Turn-On) VBAT_ = 16.8V, VCOM_ = 14.8V VBAT_ = 16.8V, VCOM_ = 16.4V VBAT_ = 16.8V, VCOM_ = 14.8V VCOM_ = 11.8V, VBAT_ = 16.8V (Note 4) VBAT_ = 8V to 19V VBAT_ = 4.75V to 8V VPDS = 10V, VEXTLD = 12V VPDS = 2V to 28V VPDS = 28V VCHG_ = 2V to 22V 0.6 4 10 50 2 -11.5 -8.00 4 0.7 1.3 2 1.4 -7.25 -4.25 150 mA A mA V mA mA A mA VBATSEL = 5.5V 20 VBATA = VBATB = 5 x VMINV VMINV = 0.93V to 2.6V VBAT_ falling VMINV = 0.93V VMINV = 2.6V VACDET falling with respect to VBATB VACDET = 3V, VACDET < VBATB, VBATA = 0 VACDET = 28V, VACDET > VBATA and VBATB VACDET falling with respect to VBATA -35 100 -35 100 0.93 -100 4.55 12.7 2.0 1 100 VTHM_= 5.5V VTHMA = VTHMB = 0 to 5.5V VBATA = VBATB = VEXTLD = 4.75V (Note 3) 0 0 2.2 2.2 8 9 11 +125 200 +125 200 2.60 +100 4.75 13.3 0.8 mV mV mV mV V nA V V V A s A CONDITIONS MIN 0 TYP MAX 5.5 100 5.5 4.3 28.0 UNITS V NA V V V
MAX1773/MAX1773A
Typical hysteresis is 100mV
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
ELECTRICAL CHARACTERISTICS (continued)
(VBATA = VBATB = 16.8V, CVDD = 3.3F, VMINV = 0.93V, VEXTLD = VACDET = 28V, VTCOMP = 3V, VTHMA = VTHMB = 1.65V, VBATSEL = 0, CCOMA = CCOMB = CDISA = CDISB = CCHGA = CCHGB = CPDS = 5nF, TA = -40C to +85C, unless otherwise noted.)
DIS_ Sink Current (PMOS Turn-On) DIS_ Turn-On Clamp Voltage (VDIS_ to VEXTLD) STATUS OUTPUTS ACPRES Sink Current BATSTAT Sink Current ACPRES Leakage Current BATSTAT Leakage Current TRANSITION TIMES Battery Switchover Delay Battery Action Delay Thermistor Action Delay AC to Battery Switchover Delay Battery to AC Switchover Delay CHG_ Turn-On Delay VACDET = 2.2V, VMINV = 0.93V (Note 6) VACDET = 2.2V, VMINV = 0.93V (Note 7) VACDET = 2.2V, VMINV = 0.93V (Note 8) VACDET = 2.2V, VMINV = 0.93V (Note 9) VACDET = 2.2V, VMINV = 0.93V (Note 10) (Note 11) 130 5 260 12 10 260 530 s s s s s s V ACPRES = 0.4V V ACPRES = 5.5V VBATSTAT = 0.4V VBATSTAT = 5.5V V ACPRES = 5.5V VBATSTAT = 5.5V 1 30 1 1 1 30 mA mA A A VEXTLD = 16.8V, VDIS_ = 11.8V (Note 5) VEXTLD = 8V to 28V VEXTLD = 4.75V to 8V 2 -11.50 -8.00 -7.25 -4.25 mA V
TCOMP undervoltage lockout sets the MAX1773/MAX1773A's internal status bits for the batteries to be designated as "absent" (VTHM_ > VTCOMP). Note 3: VACDET must remain above 2.2V, except in power-up. Note 4: COMA cannot sink current until VCOMB > VBATB - 2V. Likewise, COMB cannot sink current until VCOMA > VBATA - 2V. Note 5: DISA cannot sink current until VDISB > VEXTLD - 2V. Likewise, DISB cannot sink current until VDISA > VEXTLD - 2V. Note 6: Battery Switchover Delay starts when either VCOM_ or VDIS_ of the connected battery begins to rise and ends when both VCOM_ and VDIS_ of the other battery have fallen 3V below their sources (Figures 1 and 2). Note 7: Battery Action Delay starts when the connected battery's voltage falls below 5 VMINV and ends when both VCOM_ and VDIS_ of the other battery have fallen 3V below their sources (Figures 1 and 2). Note 8: Thermistor Action Delay begins when VTHM_ of the connected battery rises above VTCOMP and ends when both VCOM_ and VDIS_ of the other battery have fallen 3V below their sources (Figures 3 and 4). Note 9: AC to Battery Switchover Delay begins when VACDET falls below its threshold and ends when both VCOM_ and VDIS_ of the battery being switched to have fallen 3V below their sources (Figure 5). Note 10: Battery to AC Switchover Delay begins when VACDET rises above its threshold and ends when VDIS_ of the battery being switched from has begun to rise (Figure 6). Note 11: CHG_ Turn-on Delay begins when VCHG_ of the battery being switched from begins to rise and ends when VCHG_ of the battery being switched to begins to fall (Figures 7 and 8). Note 2:
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
VDD ERROR vs. INPUT VOLTAGE
VIN = VACDET, BAT_ = OPEN
MAX1773-01
VDD ERROR vs. IDD
MAX1773-02
VDD ERROR vs. TEMPERATURE
MAX1773-03
0.04
0
0.5 0 VDD ERROR (%) -0.5 -1.0 IDD = 1mA -1.5 -2.0 IDD = 5A
0 -1 ERROR (%) -0.04 ERROR (%) -2 -0.08 VIN = VBAT_, VACDET = 3.3V -0.12 5 10 15 VIN (V) 20 25 30 -3 0.01 -2.5 0.1 IDD (mA) 1 10 -40 -15 10 35 60 85 TEMPERATURE (C)
BATTERY CURRENT vs. BATTERY VOLTAGE (VACDET = 20V)
MAX1773-04
TRANSITION FROM BATTERY A TO BATTERY B (MINV) (IEXTLD = 1A, CEXTLD = 66F)
MAX1773-05
TRANSITION FROM BATTERY A TO BATTERY B (MINV) (IEXTLD = 1A, CEXTLD = 66F)
15V
MAX1773-06
10 IBATTERY_ (A) TOTAL CURRENT FROM THE BATTERY
VBATB 5V 15V VEXTLD 5V VBATA 12V 5 VMINV VDISB VCOMA
5V 0 10V VDISA VCOMB 0 10V 0 5V 0 5s/div VBATA = 12V VBATB = 10.75V
8
6
4
2
0 0 4 8 12 16 20 VBATTERY_ (V) 100s/div VBATA = 12V, BATTERY A REMOVED AT 100s VBATB = 10.75V VMINV = 1.4V
2V
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
TRANSITION FROM BATTERY A TO BATTERY B (TCOMP) (IEXTLD = 4A, CEXTLD = 66F)
MAX1773-07
TRANSITION FROM BATTERY A TO BATTERY B (TCOMP) (IEXTLD = 4A, CEXTLD = 66F)
MAX1773-08
TRANSITION FROM BATTERY A TO BATTERY B (BATSEL) (IEXTLD = 4A, CEXTLD = 66F)
MAX1773-09
12V
VCOMA
10V 0
11V
11V VEXTLD 4V VDISA VCOMB
10V 0 10V 0
VEXTLD
10V
VBATSEL
4V
VTHMA 10s/div VBATA = 10.5V AT 4A VBATB = 12V AT 4A
0
VDISB 5s/div VBATA = 10.5V AT 4A VBATB = 12V AT 4A
10V 0 50s/div VBATA = 9.4V AT 4A VBATB = 10.8V AT 4A
0
TRANSITION FROM AC ADAPTER TO BATTERY A (IEXTLD = 4A, CEXTLD = 66F)
MAX1773-10
TRANSITION FROM TRANSITION FROM BATTERY A TO AC ADAPTER (IEXTLD = 4A, CEXTLD = 66F)
20V IBATA (CURRENT FROM THE BATTERY) VBATA 20V
MAX1773-11
10A 0 -10A 12V 10V
VACDET VBATA 10V
VEXTLD VDISA 10V
VDISA VCHGA 0 20s/div VBATA = 10.8V AT 4A VACADAPTER = 17.5V AT 4A 100s/div VACADAPTER = 17.5A AT 4A VBATA = 10.5V AT 4A VACADAPTER APPLIED AT 240s CHARGER INPUT OPEN
10V 0 10V 0
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Power Source Selector for Dual-Battery Systems
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 NAME BATA THMA CHGA DISA COMA GND MINV EXTLD PDS ACDET BATSTAT ACPRES BATSEL TCOMP VDD COMB DISB CHGB THMB BATB Battery A Connection Thermistor A Input Open-Drain Gate Driver for Charge Path MOSFET to Battery A Gate Driver for Discharge Path MOSFET to Battery A. Switches from VEXTLD to (VEXTLD - 9.5V). Gate Driver for Common Path MOSFET to Battery A. Switches from VBATA to (VBATA - 9.5V). Ground Minimum Operating Voltage Set Point. The battery voltage switchover set point is 5 x VMINV. External Load Connection. Source connection for the PDS, DISA, and DISB MOSFETs. Gate Driver for the AC Adapter MOSFET AC Adapter Detection Input Open-Drain Battery Status Output. Use a pullup resistor to the system logic supply. Open-Drain AC Presence Output. Use a pullup resistor to the system logic supply. Battery Select Digital Input. Selects which battery to charge or discharge. Externally Set Thermistor Trip Point. Sets the thermistor voltage level for detecting the battery's presence. Linear Regulator Output Gate Driver for Common Path MOSFET to Battery B. Switches from VBATB to (VBATB - 9.5V). Gate Driver for Discharge Path MOSFET to Battery B. Switches from VEXTLD to (VEXTLD - 9.5V). Open-Drain Gate Driver for Charge Path MOSFET to Battery B Thermistor B Input Battery B Connection FUNCTION
MAX1773/MAX1773A
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
Transition Time Diagrams
(VCOM_GS = COM_ turn-on clamp voltage, VDIS_GS = DIS_ turn-on clamp voltage, VCHARGER = system step-down charger output.)
MAX1773-Fig-01
MAX1773-Fig-02
VBATA VCOMA VDISA
5 VMINV VBATA VBATA + VCOM_GS VEXTLD VEXTLD + VDIS_GS 3V VBATB VBATB + VCOM_GS 3V VEXTLD VEXTLD + VDIS_GS
VBATB VCOMB VDISB
5 VMINV VBATB VBATB + VCOM_GS VEXTLD VEXTLD + VDIS_GS
VCOMB
VCOMA
3V VBATA VBATA + VCOM_GS 3V VEXTLD VEXTLD + VDIS_GS
VDISB
VDISA
BATTERY ACTION DELAY
VTHMA < VTCOMP VTHMB < VTCOMP
BATTERY ACTION DELAY
VTHMA < VTCOMP VTHMB < VTCOMP
BATTERY SWITCHOVER DELAY
BATTERY SWITCHOVER DELAY
Figure 1. Battery Delay (Battery A to Battery B)
Figure 2. Battery Delay (Battery B to Battery A)
MAX1773-Fig-03
MAX1773-Fig-04
VTHMA VCOMA VDISA
VTCOMP VBATA VBATA + VCOM_GS VEXTLD VEXTLD + VDIS_GS
VTHMB VCOMB VDISB
VTCOMP VBATB VBATB + VCOM_GS VEXTLD VEXTLD + VDIS_GS
VCOMB
3V VBATB VBATB + VCOM_GS 3V VEXTLD VEXTLD + VDIS_GS VTHMB < VTCOMP
VCOMA
3V VBATA VBATA + VCOM_GS 3V VEXTLD VEXTLD + VDIS_GS VTHMA < VTCOMP
VDISB
VDISA
THERMISTOR ACTION DELAY BATTERY SWITCHOVER DELAY
THERMISTOR ACTION DELAY BATTERY SWITCHOVER DELAY
Figure 3. Thermistor Switchover Delay (Battery A to Battery B)
Figure 4. Thermistor Switchover Delay (Battery B to Battery A)
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
Transition Time Diagrams (continued)
(VCOM_GS = COM_ turn-on clamp voltage, VDIS_GS = DIS_ turn-on clamp voltage, VCHARGER = system step-down charger output.)
MAX1773-Fig-05
MAX1773-Fig-06
VACDET
ACDET TO BAT_ TRIP THRESHOLD
VACDET
ACDET TO BAT_ TRIP THRESHOLD
VEXTLD 3V VDIS_ VEXTLD + VDIS_GS VDIS_
VEXTLD
VEXTLD + VDIS_GS
AC TO BATTERY SWITCHOVER DELAY VBAT_ > 5 VMINV VTHM_ < VTCOMP
BATTERY TO AC SWITCHOVER DELAY VBAT_ > 5 VMINV VTHM_ < VTCOMP
Figure 5. AC to Battery Switchover Delay
Figure 6. Battery to AC Switchover Delay
MAX1773-Fig-07
MAX1773-Fig-08
VBATSEL
VBATSEL
VCHGA
VCHARGER
VCHGB
VCHARGER
VCHARGER VCHGB VCHGA
VCHARGER
CHG_ TURN-ON DELAY
VTHMA < VTCOMP VTHMB < VTCOMP VTHMA < VTCOMP VTHMB < VTCOMP
CHG_ TURN-ON DELAY
Figure 7. Charge Turn-On Delay (Battery A to Battery B)
Figure 8. Charge Turn-On Delay (Battery B to Battery A)
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11
Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
Table 1. AC Adapter States
BATSEL 0 0 1 1 BATTERY A Present Absent X X BATTERY B X X Present Absent BATSTAT 0 1 1 0 CONNECTION STATE AC adapter is connected to load. Battery A's charge path connected. AC adapter is connected to load. AC adapter is connected to load. Battery B's charge path connected. AC adapter is connected to load.
X = Don't care, Present: VTHM_ < VTCOMP, Absent: VTHM_ > VTCOMP, ACPRES = 0
Table 2. Simplified Standard Battery States (without latches)
BATSEL 0 X X X X 1 BATTERY A Present Present Present X Absent X VBATA >5 x VMINV >5 x VMINV >5 x VMINV <5 x VMINV X X BATTERY B X Absent X Present Present Present VBATB X X < 5 x VMINV > 5 x VMINV > 5 x VMINV > 5 x VMINV BATSTAT 0 0 0 1 1 1 CONNECTION STATE Battery A is connected to the load. Battery A is connected to the load. Battery A is connected to the load. Battery B is connected to the load. Battery B is connected to the load. Battery B is connected to the load.
X = Don't care, Present: VTHM_ < VTCOMP, Absent: VTHM_ > VTCOMP
Detailed Description
The MAX1773/MAX1773A provide the functions necessary to allow an external controller to manage the power connections needed for two battery packs, an AC adapter input, a battery charger, and the system load. The MAX1773/MAX1773A use seven PMOS FETs to provide all the switching necessary in systems using a step-down charger powered by the AC adapter (Figures 9 and 10). The MAX1773/MAX1773A automatically adapt to many transient conditions--such as AC plug-in, battery hot swapping, and battery switchover-- to provide constant power to the system without requiring real-time support from an external controller. The MAX1773/MAX1773A draw their power from the highest voltage supply present (Figure 11).
tery when no AC adapter is present. AC adapter States mode provides functionality when an AC Adapter is present. Standard Battery States mode provides functionality when one or both batteries are present, the AC adapter is not present, and EXTLD is above 2.2V. The Standard Battery States mode requires an external supply with an output voltage between 2.2V and 4.5V for ACDET, as shown in Figure 10. The external power supply must be powered from EXTLD.
AC Adapter States
The MAX1773/MAX1773A check for the presence of an AC adapter by sensing the voltage at ACDET. When VACDET exceeds the batteries' voltage and 4.75V, then the MAX1773/MAX1773A use the AC adapter to power the load. In addition, if the selected battery is present, the MAX1773/MAX1773A connect the selected battery's charge path. See Table 1 for a detailed listing of the MAX1773/MAX1773A states for operation with an AC adapter detected.
Battery Detection
The MAX1773/MAX1773A monitor the battery's thermistor voltage to determine the presence of the battery. The devices compare the battery's thermistor voltage (VTHM_) to the thermistor trip point (VTCOMP). If VTHM_ < VTCOMP, then the MAX1773/MAX1773A assume that the battery is present. However, if VTHM_ > VTCOMP, the MAX1773/MAX1773A assume that the battery is absent and do not charge or discharge the battery.
Standard Battery States
When the AC adapter power supply is not present, the MAX1773/MAX1773A use the batteries to supply the load. BATSEL allows an external controller to select a battery. Table 2 shows the simplified standard battery states that normally control operation. However, the Battery Switchover Latch, the Low-Battery Latch, and the Discharged Battery Latch are able to suspend the state table and provide additional functionality.
Modes of Operation
The MAX1773/MAX1773A provide three modes of operation. Start-up States mode provides functionality when the MAX1773/MAX1773A are initially powered by a bat12
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
STEP-DOWN CHARGER AC-ADAPTER SUPPLY
R12 R14 VBATA+ COMA CHGA CHGB VBATB+ COMB PDS
DISA
DISB
EXTLD SYSTEM
POWER CONNECTIONS
Figure 9. 7-MOSFET Topology
Table 3. Startup States
VBATA >5 x VMINV <5 x VMINV X X <5 x VMINV <5 x VMINV X VBATB X >5 x VMINV >5 x VMINV X <5 x VMINV X <5 x VMINV BATTERY A Present Present Absent Absent X X Absent BATTERY B X Present Present Absent X Absent X CONNECTION STATE Battery A is connected to the load. Battery B is connected to the load. Battery B is connected to the load. No connections. No connections. No connections. No connections.
X = Don't care, Present: VTHM_ < VTCOMP, Absent: VTHM_ > VTCOMP
The Battery Switchover Latch stops the MAX1773/ MAX1773A from oscillating when the device switches from the selected battery and then the selected battery's voltage recovers. According to the state table, the MAX1773/MAX1773A would switch back to the selected battery as soon as the battery's voltage recovered. The Battery Switchover Latch suspends the state table as soon as the MAX1773/MAX1773A switch over to the nonselected battery. This causes the MAX1773/MAX1773A to continue to power from the nonselected battery unless the latch is cleared. The Battery Switchover Latch is cleared when BATSEL is toggled (to select the other battery), when in the Startup States mode, in the AC Adapter States mode, and when the selected battery is removed (VTHM_ > VTCOMP).
To prevent the MAX1773/MAX1773A from switching to a discharged battery, the Low-Battery Latch suspends the state table when the unconnected battery's voltage is below 5 VMINV and the discharging battery's voltage drops below 5 VMINV. Instead of switching to the unconnected battery, the MAX1773/MAX1773A continue to power from the discharging battery. This latch is cleared when the unconnected battery is removed (VTHM_ > VTCOMP), when in the Startup States mode, when in the AC Adapter States mode, and if the unconnected battery's voltage rises above 5 VMINV. The Discharged Battery Latch sets whenever the MAX1773/MAX1773A are in the Standard Battery States mode, both batteries are present (VTHM_ < VTCOMP), one of the batteries is low (VBAT_ < 5 VMINV), and the other battery's voltage is below V ACDET . While the
13
______________________________________________________________________________________
Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
SYSTEM LOGIC SUPPLY 500k 500k
FROM HOST P
BATSEL TO HOST P AC ADAPTER INPUT 100k 0.1F P7 3.3k ACDET PDS R13 8k EXTLD 3.3V 10k BATTERY A THMA BATA ACPRES BATSTAT
VDD 28.7k MINV 100k 10k 0.33F 3.3V
MAX1773 MAX1773A
TCOMP 100k
10k
THMB BATB 1.5F
BATTERY B
1.5F COMA DISA CHGA COMB DISB CHGB
P1 STEP-DOWN CHARGER OUTPUT INPUT
R12 8k
R14 8k
P4 OUTPUT 3.3V DC-DC CONVERTER INPUT
SYSTEM LOAD
66F
Figure 10. Standard Application Circuit
Discharged Battery Latch is set, the state table is suspended, the MAX1773/MAX1773A are not allowed to switch batteries, and the Low Battery Latch is cleared. The Discharged Battery Latch is cleared when both batteries are above VACDET, in the AC Adapter States mode, and in the Startup States mode.
Startup States
When V ACDET rises at startup, the MAX1773/ MAX1773A use Startup States. See Table 3 for a detailed listing of the MAX1773/MAX1773A states in this mode. Note that once ACDET rises above 2.2V, the MAX1773/MAX1773A are no longer in the Startup
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Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
BATA BATB EXTLD LINEAR REGULATOR VDD UVLO
MAX1773 MAX1773A
9.5V LOGIC ACDET + + _ _ GND MINV _ 9.5V DISB PDS CHGA THMA TCOMP + _ VDD CHGB 9.5V DISA + _ 9.5V COMA COMB
BATSEL
Figure 11. Functional Diagram
States mode and enters either the Standard Battery States mode or the AC Adapter States mode.
Status and Configuration
BATSTAT and ACPRES provide information to an external controller. Table 4 shows the different states of BATSTAT and ACPRES.
______________________________________________________________________________________
+
THMB
+ _ DELAY 60s
ACPRES
BATSTAT
In the AC Adapter States mode, the BATSEL Action Delay (see Electrical Characteristics) allows the external controller to tell if both batteries are absent. When both batteries are absent in the AC Adapter States mode and BATSEL changes states, BATSTAT is immediately updated. However, changes to the connection states are delayed (see Table 1 for connection states).
15
Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
Table 4. Status Bits
MODE All Startup States Standard Battery States Standard Battery States AC Adapter States AC Adapter States Selected Battery Discharge Path Connected Other Battery Discharge Path Connected Selected Battery Charge Path Connected Selected Battery Absent STATUS VDD Undervoltage Lockout BATSTAT 1 1 BATSEL BATSEL BATSEL BATSEL ACPRES 1 1 1 1 0 0
If BATSEL is returned to its original state within the BATSEL Action Delay, then changes to the connection states are never made. Note that in the Standard Battery States mode and in the AC Adapter States mode when one or both batteries are present, both BATSTAT and the connection states are delayed during the BATSEL Update Delay.
where V GS(MIN) is the minimum P7 gate-to-source voltage, IPDS(SINK) is the PDS sink current, and RPDS is R13. The MAX1773/MAX1773A use open-collector drivers to open the charge paths. Minimize the value of the pullup resistors on the charge paths (R12 and R14) to allow the MAX1773/MAX1773A to quickly turn on the PMOS FETs; however, keep the value large enough to prevent a lower VGS than specified by the PMOS FET. The minimum VGS is: VGS(MIN) = -ICHG_(SINK) RCHG_ where VGS(MIN) is the minimum P1 or P4 gate-to-source voltage, I CHG_(SINK) is the CHG_ sink current (see Electrical Characteristics), and RCHG_ is R12 or R14.
MOSFET Drivers
To minimize the time when no supply is connected to the external load during switchover transients, the MAX1773/MAX1773A use active pullup drivers for the discharge paths (DIS_) and the common paths (COM_). When the MAX1773/MAX1773A initially begin to pull up one of these pins, they use a large current (Initial COM_ Source Current and Initial DIS_ Source Current; see Electrical Characteristics). Once the COM_ voltage rises to within 2V of VBAT_ or the DIS_ voltage rises to within 2V of VEXTLD, then a weaker driver is used to hold up the voltage (Final COM_ Source Current and Final DIS_ Source Current; see Electrical Characteristics). The MAX1773/MAX1773A are designed to prevent shoot-through from one battery to the other when transitioning from discharging one battery to discharging the other battery. To accomplish this, the MAX1773/ MAX1773A do not connect the second battery to EXTLD until it senses that the first battery is disconnected from EXTLD. See Notes 4 and 5 of Electrical Characteristics. To allow flexibility when choosing the higher voltage PDS PMOS FET (P7, Figure 10), the MAX1773/ MAX1773A do not limit the gate-to-source voltage applied to the PDS PMOSFET. The minimum VGS is set by the MAX1773/MAX1773A PDS sink current (see Electrical Characteristics) and the external resistor from PDS to EXTLD (R13): VGS(MIN) = -IPDS(SINK) RPDS
VDD Regulator The MAX1773/MAX1773A feature an internal linear regulator to provide power for itself and external circuitry. The linear regulator's output is available at VDD and is nominally 3.3V. When the linear regulator is not used to power external circuitry, bypass it with a 0.33F ceramic capacitor. To supply external loads up to 1mA, bypass the linear regulator with a 3.3F tantalum capacitor.
Applications Information
Load Switchover Transients
When power switches from one power source to another, a transient is created on the load. This transient (VEXTLD) is minimized by the capacitance on the load (CEXTLD). The voltage transient can be approximated as: i x t SWITCHOVER VEXTLD = EXLTLD CEXTLD where tSWITCHOVER is the time where no supply is connected to the EXTLD.
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______________________________________________________________________________________
Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
ES EN T, N IN BA SE O BA TB RT ED TTER IN IES SE RT ,A ED SE AC LE AD CT AP ED TE RR EM VB OV AT ED A EX FALL TE SB R VB NAL ELO W AT B F CON 5 AC ALL TR V OL M AD S B AP E LE INV TE LOW R RE RA A PP 5 CTS LIE VM D IN V, SY ST EM EX SH TE UT RN SD AL OW CO N NT RO LL ER RE AC TS
PR AC
20V VACDET VEXTLD 8V 12.6V 8V 12.6V 8V BATSEL BATSTAT ACPRES t0 0 1 0 t1 0 0 0 t2 0 0 0 t3 0 0 1 t4 0 1 1 t5 1 1 1 t6 1 0 1 t7 1 1 0 t8 0 0 0 t9 0 0 0 3.3V 20V
VBATA
VBATB
Figure 12. Charge/Discharge Example
In applications where the battery voltage always falls away slowly, tSWITCHOVER is primarily composed of the Battery Switchover Delay. However, in applications where the battery voltage can suddenly fall away, tSWITCHOVER is substantially increased because it is primarily composed of the Battery Action Delay (Figures 1 and 2). Ideally, when a battery is removed from the system, the thermistor connection is broken before the battery's power path is broken. In this case, tSWITCHOVER is typically bound by the Thermistor Action Delay (Figures 3 and 4). However, if the battery's power path is broken first, then tSWITCHOVER primarily consists of the shorter of the following times: time until the thermistor connection is broken plus the Thermistor Action Delay, or the Battery Action Delay.
BA
TA
IPK =
VEXTLOAD RSOURCE + RSWITCH + RESR
where VEXTLOAD is the voltage difference between the supply switched off and the supply switched on, RSOURCE is the source resistance of the power supply switched on, RSWITCH is the RDS(ON) of the PMOS FETs in the path, and RESR is the equivalent series resistance of the output capacitance. The duration of the current transient is determined by RSOURCE, RSWITCH, RESR, and the output capacitance. Smaller resistances and less output capacitance reduce the transient duration.
Typical Operation
Figure 12 shows a typical discharge and charge cycle for a system utilizing the MAX1773/MAX1773A, two 3-cell lithium-ion (Li+) batteries, and a 20V AC adapter power supply. The diagram starts with the AC adapter applied, no batteries present, and battery A selected (see AC Adapter States). BATSTAT = BATSEL = 1 indicates that battery A is not present and battery A's
17
Source Switchover Transients
When the MAX1773/MAX1773A suddenly switch a power supply to the load, they create a current transient from the source to charge up the capacitance on the load. The peak current drawn is approximated by:
______________________________________________________________________________________
Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
Table 5. Recommended Manufacturers
SUPPLIER Fairchild IR Siliconix PHONE 408-822-2000 310-322-3331 408-988-8000 FAX 408-822-2102 310-322-3332 408-970-3950
At t8, the external controller recognizes that battery B is charged and changes BATSEL to battery A. BATSTAT goes to BATSEL (0) to indicate that battery A is present. After t9, the batteries are fully charged and the system is ready for another cycle.
Power MOSFET Selection
The MAX1773/MAX1773A do not place stringent requirements on the external PMOS FETs. Use PMOS FETs with low VGS thresholds (logic level FETs). Low RDS(ON) PMOS FETs are desirable since the PMOS FET's resistance directly contributes to power losses. Also, ensure that the PMOS FET's VDS and VGS ratings exceed the specific circuit requirements. See Table 5 for a list of recommended manufacturers.
charge path is not connected. If the external controller polled the MAX1773/MAX1773A as described in Status and Configuration, then BATSTAT would return BATSEL (0) to indicate that battery B is not present. At t 1 , battery A is inserted and the MAX1773/ MAX1773A connect battery A's charge path. Note that BATSTAT changes to BATSEL (0) to indicate that battery A is present. At t2, battery B is inserted. BATSTAT does not change and still indicates that battery A is present. At t 3 , the AC adapter is removed and the MAX1773/MAX1773A automatically disconnect battery A's charge path and connect battery A's discharge path (see Standard Battery States). ACPRES changes to 1 to indicate that the AC adapter source is no longer present. BATSTAT = BATSEL (0) to indicate that battery A is present and supplying the load. Between t3 and t4, battery A discharges as it supplies the load. At t4, battery A's voltage falls below 5 VMIN, and the MAX1773/MAX1773A automatically disconnect battery A's discharge path and connect battery B's discharge path. BATSTAT goes to BATSEL (1) to indicate that battery A is no longer supplying the load. Shortly after BATSTAT goes high, the external controller should catch up to the MAX1773/MAX1773A and change BATSEL. This is shown at t5. BATSTAT remains at 1, indicating that battery B is present and supplying the load. At t 6 , battery B falls below 5 V MIN, and the MAX1773/MAX1773A automatically disconnect battery B's discharge path and connect battery A's discharge path. BATSTAT changes to BATSEL (0) to indicate that battery B is no longer supplying the load. At this point, the external controller orders a controlled shutdown of the system and drastically reduces the supply current. At t7, the AC adapter supply is reconnected to the system. The MAX1773/MAX1773A automatically disconnect battery A's discharge path, connects the AC adapter's load path (PDS switch), and connects battery B's charge path. BATSTAT goes to BATSEL (1) to indicate that battery B is present. ACPRES goes to 0 to indicate that the AC adapter source is present.
Layout Guidelines
The MAX1773/MAX1773A do not use fast switching times or high frequencies. Therefore, the layout requirements are minimal. Keep the gate connections to the external PMOS FETs short to minimize capacitive coupling, reduce parasitic inductance, and ensure stability. In addition, minimize the power path length when possible to reduce the path's resistance. See the MAX1773 evaluation kit for a layout example.
Pin Configuration
TOP VIEW
BATA 1 THMA 2 CHGA 3 DISA 4 COMA 5 GND 6 MINV 7 EXTLD 8 PDS 9 ACDET 10 20 BATB 19 THMB 18 CHGB 17 DISB
MAX1773 MAX1773A
16 COMB 15 VDD 14 TCOMP 13 BATSEL 12 ACPRES 11 BATSTAT
TSSOP
Chip Information
TRANSISTOR COUNT: 5245 PROCESS: BiCMOS
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Power Source Selector for Dual-Battery Systems
Differences Between MAX1773 and MAX1773A
This section discusses the differences between the MAX1773 and MAX1773A for the situations detailed. Note that the MAX1773 and MAX1773A are pin-to-pin compatible. PDS FET Switching MAX1773: If battery B is selected but absent, and battery A is inserted with a voltage less than five times MINV, when an adapter is inserted, the PDS FET does not turn on. The problem also occurs if battery A is selected but absent, and battery B is inserted with a voltage less than five times MINV, when an adapter is inserted, the PDS FET does not turn on. In the MAX1773A, when the sequences discussed are encountered, the part has been changed to enable the PDS FET. This results in the PDS FET having to dissipate less energy in the MAX1773A. Selected Battery Present But Under-Voltage MAX1773: When the selected battery is present and less than five times the MINV voltage, and a battery above five times the MINV voltage is inserted at the nonselected slot. In this case, the MAX1773 will not enable discharge from the nonselected slot if the THM_ pin of the nonselected battery is valid after the TCOMP pin goes high. In the MAX1773A the order in which the THM_ and TCOMP pins become enabled is unimportant for these states. This results in this behavior not being encountered in the MAX1773A. Switchover to Nonselected Battery Upon Adapter Removal MAX1773: When the selected battery is present and less than five times MINV, and the nonselected battery is present and greater than five times MINV. The MAX1773 enables the discharge path from the nonselected battery, which has a voltage greater than five times MINV, which is an expected operation for the part. If the AC adapter is then inserted, the charge path to the selected battery is enabled, this is also expected operation. When the adapter is removed, the MAX1773 does not switch to the nonselected battery, which is the issue. In the MAX1773A, when the AC adapter is removed in the scenario detailed, three separate conditions are possible: 1) A charger is present but does not charge the selected battery. This can happen if the input current-limit feature in the charger has been activated, reducing the charger current to zero. The AC adapter is then removed. In this case the MAX1773A allows discharge from the unselected battery, whose voltage was above 5 x MINV. 2) A charger is present and charges the selected battery. The battery is charged sufficiently so that it can support the system load for more then 10ms. (Assuming the typical application circuit with 100k and 0.1F on the AC adapter input.) When the AC adapter is removed, the MAX1773A correctly allows discharge from the selected battery. 3) In the third scenario, the charger charges the selected battery, but before the battery is sufficiently charged to support the system load, the AC adapter is removed. In this case, the MAX1773A does not allow discharge from the unselected battery, whose voltage is above 5 x MINV. The limiting condition is that the battery has to be sufficiently charged to support the system load for 10ms.
MAX1773/MAX1773A
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19
Power Source Selector for Dual-Battery Systems MAX1773/MAX1773A
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.)
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.
20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
TSSOP4.40mm.EPS

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