MAX1538ETI+-MAX1538ETI+T Fast Delivery |IC PHOENIX CO.,LIMITED

MAX1538ETI+ ,Power-Source Selector for Dual-Battery SystemsELECTRICAL CHARACTERISTICS(V = V = V = 16.8V, C = 1µF, V = V = 0.93V, V = V = 28V, V = V = V = 0,BA ..
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MAX4173HESA+ ,Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense AmplifierFeaturesThe MAX4173 low-cost, precision, high-side current-♦ Low-Cost, Compact Current-Sense Soluti ..
MAX4173HESA+T ,Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense Amplifierfeatures a voltage output that eliminates the need forRange, Functional Down to 0V, Independent ofg ..
MAX4173HEUT ,Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense AmplifierMAX4173 Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense Amplifier
MAX4173HEUT+T ,Low-Cost, SOT23, Voltage-Output, High-Side Current-Sense AmplifierApplicationsRS+ RS-+3V TO +28VNotebook ComputersVCCPortable/Battery-Powered Systems0.1μFSmart Batte ..
MAX4173TESA ,Low-Cost / SOT23 / Voltage-Output / High-Side Current-Sense AmplifierApplications+3V TO +28VVCCNotebook Computers0.1μFPortable/Battery-Powered SystemsMAX4173T/F/HSmart ..
MAX4173TESA ,Low-Cost / SOT23 / Voltage-Output / High-Side Current-Sense Amplifierfeatures a voltage output that eliminates the need forIndependent of Supply Voltagegain-setting res ..

MAX1538ETI+-MAX1538ETI+T
Power-Source Selector for Dual-Battery Systems
General Description
The MAX1538 selector provides power-source control
for dual-battery systems. The device selects between
an AC adapter and dual batteries based on the pres-
ence of the three power sources and the state of
charge of each battery. The MAX1538 includes analog
comparators to detect AC/airline-adapter presence and
determine battery undervoltage. Fast analog circuitry
allows the device to switch between power sources to
implement a break-before-make time, which allows hot
swapping of battery packs. The MAX1538 indepen-
dently performs power-source monitoring and selec-
tion, freeing the system power-management µP for
other tasks. This simplifies the development of µP
power-management firmware and allows the µP to enter
standby, reducing system power consumption.
The MAX1538 supports “relearn mode,” which allows
the system to measure and fully utilize battery capacity.
In this state, the part allows the selected battery to be
discharged even when an AC adapter is present. The
MAX1538 can also be used to power the system in an
aircraft. On detecting an airline adapter, the MAX1538
automatically disables charging or discharging of bat-
tery packs and only allows the system to be powered
from the adapter.
The MAX1538 is available in a space-saving 28-pin thin
QFN package with a maximum footprint of 5mm x 5mm.
Applications
Notebook and Subnotebook Computers
Internet Tablets
Dual-Battery Portable Equipment
FeaturesAutomatically Detects and Responds to
Low-Battery Voltage Condition
Battery Insertion and Removal
AC-Adapter Presence
Airline-Adapter PresenceStep-Down and Step-Up Charger CompatibilityFast Break-Before-Make Selection
Allows Hot Swapping of Power Sources
No External Schottky Diodes Needed50µA Maximum Battery Quiescent CurrentImplements Battery Capacity RelearningAllows Usage of Aircraft SupplyDirect Drive of P-Channel MOSFETsSimplifies Power-Management µP Firmware4.75V to 28V AC-Adapter Input Voltage RangeSmall 28-Pin Thin QFN Package (5mm x 5mm)
MAX1538
Power-Source Selector for
Dual-Battery Systems
19-3169; Rev 0; 1/04
MAX1538
REVBLK
DISA
DISB
BATA
BATB
CHGB
CHGA
CHGIN
ADPIN
EXTLD
ADPBLK
AIRDET
ACDET
MINVA
MINVB
VDD
CHRG
BATSEL
RELRN
OUT2
OUT1
OUT0
GND
BATSUP
BATTERY
CHARGER
CHG_OUT
SYSTEM LOAD
ADAPTER
BATTERY BBATTERY A
PARTTEMP RANGEPIN-PACKAGE
MAX1538ETI-40°C to +85°C28 Thin QFN
Ordering Information
Pin Configuration appears at end of data sheet.ypical Operating Circuit
MAX1538
Power-Source Selector for
Dual-Battery Systems
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VBATA= VBATB= VCHGIN= 16.8V, CVDD= 1µF, VMINVA= VMINVB= 0.93V, VEXTLD= VADPIN= 28V, VCHRG= VBATSEL= VRELRN= 0,
CADPPWR= CREVBLK = CADPBLK = CDISBAT= CDISA= CDISB= CCHGA= CCHGB= 4.7nF, TA = 0°C to +85°C, unless otherwise noted.
Typical values are at TA= +25°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.
VEXTLD, VBATSUP, VADPIN, VBATA, VBATB,
VCHGINto GND .................................................-0.3V to +30V
VADPPWRto GND...................................-0.3V to (VADPIN+ 0.3V)
VREVBLK, VADPBLKto GND...................-0.3V to (VEXTLD+ 0.3V)
VCHGA, VCHGB, VDISBATto GND..........-0.3V to (VCHGIN+ 0.3V)
VDISAto GND..........................................-0.3V to (VBATA+ 0.3V)
VDISBto GND..........................................-0.3V to (VBATB+ 0.3V)
VDD, VCHRG, VBATSEL, VRELRN, VOUT0, VOUT1, VOUT2,
VMINVA, VMINVB, VAIRDET, VACDETto GND..........-0.3V to +6V
Continuous Power Dissipation (TA= +70°C)
28-Pin Thin QFN 5mm x 5mm
(derate 20.8mW/°C above +70°C)..........................1666.7mW
Operating Temperature Range
MAX1538ETI....................................................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETERCONDITIONSMINTYPMAXUNITS
ADPIN, EXTLD Supply Voltage
Range4.7528.00V
CHGIN, BATA, BATB and
BATSUP Supply Voltage Range4.7519.00V
VADPIN = highest,
VADPPWR = high2150
VADPIN = highest,
VADPPWR = low2354
VBATA = highest,
VDISA = high2142
VBATA = highest, VDISA = low2450
VBATB = highest,
VDISB = high2142
VBATB = highest, VDISB = low2450
ADPIN, BATA, BATB, BATSUP
Quiescent Current (Current from
the Highest Voltage Supply)
VBATA = 4.75V to 19V,
VBATB = 4.75V to 19V,
VBATSUP = 4.75V to 19V,
VADPIN = 4.75V to 28V,
no external load at VDD
VBATSUP = highest1840
VADPPWR = high0.010.5ADPIN Quiescent Current (ADPIN
Current When Not the Highest
Voltage)
VADPIN = 4.75V to 18V,
no external load at VDDVADPPWR = low2.66
VDISA = high3.96.0BATA Quiescent Current (BATA
Current When Not the Highest
Voltage)
VBATA = 4.75V to 19V,
no external load at VDDVDISA = low7.012
VDISB = high3.96.0BATB Quiescent Current (BATB
Current When Not the Highest
Voltage)
VBATB = 4.75V to 19V,
no external load at VDDVDISB = low7.012
Adapter selected (REVBLK or ADPBLK pins low)3.06.1EXTLD Quiescent CurrentAdapter not selected (REVBLK and ADPBLK pins high)0.021.0µA
AC or ai r l i ne state ( C H G A, C H GB, and D IS BAT p i ns hi g h) 0.031.5
Charge state (CHGA or CHGB pin low, DISBAT pin high)3.16.2CHGIN Quiescent Current
Discharge or relearn state (CHGA or CHGB pin low,
DISBAT pin low)6.112.1
MAX1538
Power-Source Selector for
Dual-Battery Systems
ELECTRICAL CHARACTERISTICS (continued)
(VBATA= VBATB= VCHGIN= 16.8V, CVDD= 1µF, VMINVA= VMINVB= 0.93V, VEXTLD= VADPIN= 28V, VCHRG= VBATSEL= VRELRN= 0,
CADPPWR= CREVBLK = CADPBLK = CDISBAT= CDISA= CDISB= CCHGA= CCHGB= 4.7nF, TA = 0°C to +85°C, unless otherwise noted.
Typical values are at TA= +25°C.)
PARAMETERCONDITIONSMINTYPMAXUNITS
LINEAR REGULATOR
VDD Output VoltageIVDD = 0 to 100µA3.2703.33.330V
VBATA or VBATB = 5V to 19V, VADPIN = 5V1.0
VBATA = VBATB = 5V, VADPIN = 5V to 28V1.0VDD Power-Supply Rejection
RatioVBATA, VBATB, or VADPIN = 5V to 19V, sawtooth at
10V/µs, other supplies = 12V1
mV / V
VDD Undervoltage LockoutRising edge, relative to regulation point-55-10mV
COMPARATORS
ACDET, AIRDET Input Voltage
Range05.5V
ACDET, AIRDET Input Bias
CurrentVAIRDET = VACDET = 3V0.11µA
ACDET, AIRDET Trip ThresholdInput falling1.972.02.03V
ACDET, AIRDET Hysteresis20mV
MINV_ Operating Voltage Range0.932.60V
MINV_ Input Bias CurrentVMINV_ = 0.93V to 2.6V-50+50nA
VMINV_ = 0.93V4.6054.654.695
VMINV_ = 1.5V7.4557.57.545BAT_ Minimum Voltage Trip
ThresholdVBAT_ falling
VMINV_ = 2.6V12.931313.07
BAT_ Minimum Voltage
Hysteresis125mV
BAT_ Pack Removal Detection
ThresholdVBAT_ falling1.902.02.10V
BAT_ Pack Removal Hysteresis85mV
GATE DRIVERS (Note 1)
VSOURCE = 15V, VPIN = 7.5V1860ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Source Current (PMOS
Turn-Off)VSOURCE = 15V, VPIN = 13V315
VSOURCE = 15V, VPIN = 15V2070ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Sink Current (PMOS
Turn-On)VSOURCE = 15V, VPIN = 9.5V1055
VSOURCE = 8V to 19V (ADPPWR, REVBLK, and AOPBLK,
VSOURCE = 8V to 28V)-11.0-9.0-7.0ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-On Clamp Voltage
(VPIN to VSOURCE)VSOURCE = 4.75V to 8V-8.00-3.65
MAX1538
Power-Source Selector for
Dual-Battery Systems
ELECTRICAL CHARACTERISTICS (continued)
(VBATA= VBATB= VCHGIN= 16.8V, CVDD= 1µF, VMINVA= VMINVB= 0.93V, VEXTLD= VADPIN= 28V, VCHRG= VBATSEL= VRELRN= 0,
CADPPWR= CREVBLK = CADPBLK = CDISBAT= CDISA= CDISB= CCHGA= CCHGB= 4.7nF, TA = 0°C to +85°C, unless otherwise noted.
Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-On Time
VSOURCE = 15V, VPIN = 13V to VPIN = 9V0.30.88µs
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-Off Time
VSOURCE = 15V, VPIN = 9V to VPIN = 13V0.30.88µs
STATE SELECTION INPUTS
CHRG, BATSEL, RELRN Input
Low Voltage0.8V
CHRG, BATSEL, RELRN Input
High Voltage2.1V
CHRG, BATSEL, RELRN Input
Leakage CurrentVCHRG = VBATSEL = VRELRN = 5.5V0.11µA
STATE OUTPUTS
VOUT_ = 0.4V1OUT0, OUT1, OUT2 Sink CurrentVOUT_ = 5.5V25mA
OUT0, OUT1, OUT2 Leakage
CurrentV OU T _ = 5.5V 0.11µA
TRANSITION TIMES
MINV_ Comparator DelaytMINVVBAT_ = 5.5V to VBAT_ = 4.45V5.511µs
AIRDET and ACDET Comparator
DelaytADPFalling edge with -20mV overdrive2.76.0µs
BAT_ Removal Comparator DelayFalling edge with -20mV overdrive10µs
Battery-Insertion Blanking TimetBBLANK132131ms
State-Machine Delay50ns
MOSFET Turn-On DelaytTRANS57.510µs
MAX1538
Power-Source Selector for
Dual-Battery Systems
ELECTRICAL CHARACTERISTICS
(VBATA= VBATB= VCHGIN= 16.8V, CVDD = 1µF, VMINVA= VMINVB= 0.93V, VEXTLD= VADPIN= 28V, VCHRG= VBATSEL= VRELRN= 0,
CADPPWR= CREVBLK = CADPBLK = CDISBAT= CDISA= CDISB= CCHGA= CCHGB= 4.7nF, TA = -40°C to +85°C, unless otherwise noted.)
(Note 2)
PARAMETERCONDITIONSMINMAXUNITS
ADPIN, EXTLD Supply Voltage
Range4.7528.00V
CHGIN, BATA, BATB, and
BATSUP Supply Voltage Range4.7519.00V
VADPIN = highest,
VADPPWR = high50
VADPIN = highest,
VADPPWR = low54
VBATA = highest, VDISA = high42
VBATA = highest, VDISA = low50
VBATB = highest, VDISB = high42
VBATB = highest, VDISB = low50
ADPIN, BATA, BATB, BATSUP
Quiescent Current (Current from
the Highest Voltage Supply)B AT A = 4.75V to 19V ,B AT B = 4.75V to 19V ,B AT S U P = 4.75V to 19V ,A D P IN = 4.75V to 28V ,
no exter nal l oad at V D D
VBATSUP = highest40
VADPPWR = high1ADPIN Quiescent Current (ADPIN
Current When Not the Highest
Voltage)
VADPIN = 4.75V to 18V,
no external load at VDDVADPPWR = low9
VDISA = high7.5BATA Quiescent Current (BATA
Current When Not the Highest
Voltage)
VBATA = 4.75V to 19V,
no external load at VDDVDISA = low16
VDISB = high7.5BATB Quiescent Current (BATB
Current When Not the Highest
Voltage)
VBATB = 4.75V to 19V,
no external load at VDDVDISB = low16
Adapter selected (REVBLK or ADPBLK pins low)9.5EXTLD Quiescent CurrentAdapter not selected (REVBLK and ADPBLK pins high)1.0µA
AC or ai r l i ne state ( C H G A, C H GB, and D IS BAT p i ns hi g h) 1.5
Charge state (CHGA or CHGB pin low, DISBAT pin high)10CHGIN Quiescent Current
Discharge or relearn state (CHGA or CHGB pin low,
DISBAT pin low)18.5
LINEAR REGULATOR
VDD Output VoltageIVDD = 0 to 100µA3.2703.330V
VDD Undervoltage LockoutRising edge, relative to regulation point-60-10mV
COMPARATORS
ACDET, AIRDET Input Voltage
Range05.5V
ACDET, AIRDET Trip ThresholdInput falling1.942.06V
MINV_ Operating Voltage Range0.932.60V
VMINV_ = 0.93V4.594.72
VMINV_ = 1.5V7.47.6BAT_ Minimum Voltage Trip
ThresholdVBAT_ falling
VMINV_ = 2.6V12.8613.14
MAX1538
Power-Source Selector for
Dual-Battery Systems
PARAMETERSYMBOLCONDITIONSMINMAXUNITS
BAT_ Pack Removal Detection
ThresholdVBAT_ falling1.882.12V
GATE DRIVERS (Note 1)
VSOURCE = 15V, VPIN = 7.5V18ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Source Current (PMOS
Turn-Off)VSOURCE = 15V, VPIN = 13V3
VSOURCE = 15V, VPIN = 15V20ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Sink Current (PMOS
Turn-On)VSOURCE = 15V, VPIN = 9.5V10S OU RC E = 8V to 19V ( AD P P W R, RE V BLK,
and AD P BLK, V S OU RC E = 8V to 28V ) -11.7-6.5ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-On Clamp Voltage
(VPIN to VSOURCE)VSOURCE = 4.75V to 8V-8.00-3.50
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-On Time
VSOURCE = 15V, VPIN = 13V to VPIN = 9V0.88µs
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-Off Time
VSOURCE = 15V, VPIN = 9V to VPIN = 13V0.88µs
STATE SELECTION INPUTS
CHRG, BATSEL, RELRN Input
Low Voltage0.8V
CHRG, BATSEL, RELRN Input
High Voltage2.1V
STATE OUTPUTSOU T _ = 0.4V 1OUT0, OUT1, OUT2 Sink CurrentV OU T _ = 5.5V 25mA
TRANSITION TIMES
MINV_ Comparator DelaytMINVVBAT_ = 5.5V to VBAT_ = 4.45V11µs
AIRDET and ACDET Comparator
DelaytADPFalling edge with -20mV overdrive6µs
Battery-Insertion Blanking TimetBBLANK1231ms
MOSFET Turn-On DelaytTRANS510µs
Note 1:VPINrefers to the voltage of the driver output. VSOURCErefers to the power source for the driver. ADPPWR, REVBLK, ADP-
BLK, DISBAT, DISA, DISB, CHGA, and CHGB gate drivers correspond to sources at ADPIN, EXTLD, EXTLD, CHGIN, BATA,
BATB, CHGIN, and CHGIN, respectively.
Note 2:Guaranteed by design. Not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(VBATA= VBATB= VCHGIN= 16.8V, CVDD = 1µF, VMINVA= VMINVB= 0.93V, VEXTLD= VADPIN= 28V, VCHRG= VBATSEL= VRELRN= 0,
CADPPWR= CREVBLK = CADPBLK = CDISBAT= CDISA= CDISB= CCHGA= CCHGB= 4.7nF, TA = -40°C to +85°C, unless otherwise noted.)
(Note 2)
MAX1538
Power-Source Selector for
Dual-Battery Systems
VDD LOAD REGULATION
MAX1538 toc01
VDD LOAD CURRENT (mA)
(V)
VDD vs. TEMPERATURE
MAX1538 toc02
TEMPERATURE (°C)
(V)40200-20
IBAT_ vs. VBAT_
MAX1538 toc04
BATTERY VOLTAGE (V)
BATTERY INPUT CURRENT (105
BAT_ NOT HIGHEST SUPPLY
IBAT_ vs. VBAT_
MAX1538 toc03
BATTERY VOLTAGE (V)
BATTERY INPUT CURRENT (121086
BAT_ HIGHEST SUPPLY
Typical Operating Characteristics
(Circuit of Figure 1. TA = +25°C, unless otherwise noted.)
ADAPTER INSERTION
MAX1538 toc05
10.0µs/div
20V
10V
VADPIN AND
VEXTLD
VADPBLK
VREVBLK
VOUT1
20V
10V
VADPIN
VEXTLD
VREVBLK
VADPBLK
tADP
MAX1538
Power-Source Selector for
Dual-Battery Systems
Typical Operating Characteristics (continued)
(Circuit of Figure 1. TA = +25°C, unless otherwise noted.)
SOURCE SELECTION CHANGE
MAX1538 toc10
2.00µs/div
10V
VDISB
(10V/div)
VDISA
(10V/div)
VBATB
AC-COUPLED
(5V/div)
VBATSEL
VOUT0
10V
20V
10VtTRANS
INDUCTIVE KICKNO CAPACITOR
AT BATB
BATTERY INSERTION
MAX1538 toc06
5.00ms/div
10V
VDISB
(10V/div)
VOUT0
(10V/div)
VDISA
VBATA
VEXTLD
10V
10V
20V
10V
SYSTEM LOAD = 3A
VBATB = 16.8VVBATA = 10V
A: CONTACT BOUNCE
B: BATTERY INSERTION BLANKING TIME = 22ms
BATTERY REMOVAL TIMING
MAX1538 toc08
4.00µs/div
10V
10.2V
9.8V
VOUT0
(10V/div)
VDISB
VDISA
VEXTLD
9.6V
10V
10V
5 x MINV
tMINV
(tADP FOR
ADAPTER
REMOVAL
TIMING)
tTRANS
VBATA = 16.8V
BATTERY B
REMOVED
SYSTEM LOAD = 3A
SOURCE SELECTION CHANGE
MAX1538 toc09
2.00µs/div
10V
VDISB
(10V/div)
VDISA
(10V/div)
VBATB
AC-COUPLED
(5V/div)
VBATSEL
VOUT0
10V
20V
10VtTRANS
INDUCTIVE KICK
CBATB = 1µF
SYSTEM LOAD = 3A
BATTERY REMOVAL
MAX1538 toc07
5.00ms/div
10V
VDISB
(10V/div)
VOUT0
(10V/div)
VDISA
VBATA
VEXTLD
10V
10V
20V
10V
CONTACT BOUNCE
VBATB = 16.8VVBATA = 10V
MAX1538
Power-Source Selector for
Dual-Battery Systems
PINNAMEFUNCTIONMINVAMinimum Battery A Voltage Set Point. Battery A discharge is prevented if VBATA has fallen below 5 x
VMINVA.MINVBMinimum Battery B Voltage Set Point. Battery B discharge is prevented if VBATB has fallen below 5 x
VMINVB.BATSELBattery-Selection Input. Drive to logic low to charge battery A or give discharge preference to battery A.
Drive to logic high to charge battery B or give discharge preference to battery B.RELRNBattery-Relearn Logic-Level Input. Drive RELRN high to enable battery-relearn mode.CHRGCharge-Enable Logic-Level Input. Drive CHRG high to enable the charging path from the charger to the
battery selected by BATSEL.OUT0OUT1OUT2
Selector-State Output. This open-drain output indicates the state of the MAX1538. See Table 1 for
information on decoding.ACDETAC-Adapter Detection Input. When VACDET is greater than the ACDET trip threshold (2V typ), adapter
presence is detected.AIRDETAirline-Adapter Detection Input. When VAIRDET > 2V and VACDET < 2V, the airline-adapter presence is
detected. Charging is disabled when an airline adapter is detected.ADPINAdapter Input. When VADPIN > VBATSUP, the MAX1538 is powered by ADPIN. ADPIN is the supply rail for
the ADPPWR MOSFET driver.ADPPWR
Adapter-Power P-Channel MOSFET Driver. Connect ADPPWR to the gate of P1 (Figure 1). P1 disconnects
the adapter from the system during relearn mode. Exclude P1 and leave ADPPWR disconnected if relearn
is not used. ADPPWR is driven relative to ADPIN. ADPPWR and REVBLK are driven with the same control
signal.REVBLK
Gate Drive for the Reverse-Blocking P-Channel MOSFET. Connect REVBLK to the gate of P2 (Figure 1). P2
enables and disables the AC adapter’s power path. REVBLK is driven relative to EXTLD. REVBLK and
ADPPWR are driven with the same control signal.
BREAK-BEFORE-MAKE TIMING
MAX1538 toc11
1.00µs/div
14V
16V
MOSFET
DRIVERS
12V
10V
tTRANS
MOSFET
TURN-OFF
TIMEMOSFET
TURN-ON
TIME
MOSFET FOR INITIAL
DISCHARGE PATH
MOSFET FOR FINAL
DISCHARGE PATH
FIRST SOURCE INSERTION
MAX1538 toc12
200µs/div
VADPIN
VREVBLK
VEXTLD
OUT1
OUT2, OUT0
10V
20V
20V
10V
POWER-UP TIMEypical Operating Characteristics (continued)
(Circuit of Figure 1. TA = +25°C, unless otherwise noted.)
Pin Description
MAX1538
Power-Source Selector for
Dual-Battery Systems
PINNAMEFUNCTIONADPBLK
Gate Drive for the Adapter-Blocking P-Channel MOSFET. Connect ADPBLK to the gate of P3 (Figure 1). P3
enables and disables the battery discharge path. ADPBLK is driven relative to EXTLD. ADPBLK and
DISBAT are driven with the same control signal.
15, 21N.C.Not Internally ConnectedEXTLDExternal Load. EXTLD is the supply rail for REVBLK and ADPBLK.CHGINCharger Node Input. CHGIN is the supply rail for DISBAT, CHGA, and CHGB.DISBAT
Gate Drive for the Battery-Discharge P-Channel MOSFET. Connect DISBAT to the gate of P4 (Figure 2). P4
disconnects the battery from the system load when charging from a step-up converter. Exclude P4 and
leave DISBAT disconnected if using a step-down charger. DISBAT is driven relative to CHGIN. DISBAT and
ADPBLK are driven by the same control signal.CHGA
Gate Drive for the Charge Battery A P-Channel MOSFET. Connect CHGA to the gate of P6 (Figure 1). P6
enables and disables the charge path into battery A. CHGA is driven relative to CHGIN. CHGA and DISA
are driven by the same control signal.CHGB
Gate Drive for the Charge Battery B P-Channel MOSFET. Connect CHGB to the gate of P7 (Figure 1). P7
enables and disables the charge path into battery B. CHGB is driven relative to CHGIN. CHGB and DISB
are driven by the same control signal.BATBBattery B Voltage Input. Battery undervoltage and absence is determined by measuring BATB. BATB is the
supply rail for DISB.DISB
Gate Drive for the Discharge from Battery B P-Channel MOSFET. Connect DISB to the gate of P8 (Figure 1).
P8 enables and disables the discharge path from battery B. DISB is driven relative to BATB. DISB and
CHGB are driven by the same control signal.DISA
Gate Drive for the Discharge from Battery A P-Channel MOSFET. Connect DISA to the gate of P5 (Figure 1).
P5 enables and disables the discharge path from battery A. DISA is driven relative to BATA. DISA and
CHGA are driven by the same control signal.BATABattery A Voltage Input. Battery undervoltage and absence is determined by measuring BATA. BATA is the
supply rail for DISA.BATSUPBATSUP powers the MAX1538. Diode OR BATA and BATB to BATSUP externally. ADPIN is diode
connected to BATSUP internally. Bypass with a 0.1µF capacitor from BATSUP to GND.GNDGroundVDDLinear-Regulator Output. Bypass with a 1µF capacitor from VDD to GND.
Pin Description (continued)
MAX1538
Power-Source Selector for
Dual-Battery Systems
MAX1538
REVBLK
DISA
DISB
BATA
BATB
CHGB
CHGA
CHGIN
ADPIN
EXTLD
ADPBLK
BATTERY ABATTERY B
AIRDET
ACDET
MINVA
MINVB
VDD
CHRG
BATSEL
RELRN
OUT2
OUT1
OUT0
GNDBATSUP
ADAPTER
ADPPWRR2R3P7
STEP-DOWN CHARGER
CSYS
CCHG
FOR RELEARN
MODE ONLY
CBATB
CBATAD2
R10
R11
R12
R13
0.1µF
LOGIC SUPPLY
RSNSSYSTEM LOAD
CHARGER OUTPUT
CADAPTER
0.1µF
CHARGER INPUT
OUT
Figure1. Step-Down Typical Application Circuit

Partno	Mfg	Dc	Qty	Available	Descript
MAX1538ETI+ \|MAX1538ETI	MAXIM	N/a	1870	avai	Power-Source Selector for Dual-Battery Systems
MAX1538ETI+T \|MAX1538ETIT	MAXIM	N/a	17	avai	Power-Source Selector for Dual-Battery Systems