Rainbow Electronics MAX1538 User Manual
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 presence 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 independently performs power-source monitoring and selection, 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 battery 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
Features
♦ Automatically Detects and Responds to
Low-Battery Voltage Condition
Battery Insertion and Removal
AC-Adapter Presence
Airline-Adapter Presence
♦ Step-Down and Step-Up Charger Compatibility
♦ Fast Break-Before-Make Selection
Allows Hot Swapping of Power Sources
No External Schottky Diodes Needed
♦ 50µA Maximum Battery Quiescent Current
♦ Implements Battery Capacity Relearning
♦ Allows Usage of Aircraft Supply
♦ Direct Drive of P-Channel MOSFETs
♦ Simplifies Power-Management µP Firmware
♦ 4.75V to 28V AC-Adapter Input Voltage Range
♦ Small 28-Pin Thin QFN Package (5mm x 5mm)
MAX1538
Power-Source Selector for
Dual-Battery Systems
________________________________________________________________ Maxim Integrated Products 1
19-3169; Rev 0; 1/04
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.
MAX1538
REVBLK
DISA
DISB
BATA
BATB
CHGB
CHGA
CHGIN
ADPIN
EXTLD
ADPBLK
AIRDET
ACDET
MINVA
MINVB
V
DD
CHRG
BATSEL
RELRN
OUT2
OUT1
OUT0
GND
BATSUP
BATTERY
CHARGER
CHG_OUT
SYSTEM LOAD
ADAPTER
BATTERY B
BATTERY A
Ordering Information
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
PART TEMP RANGE PIN-PACKAGE
MAX1538ETI -40°C to +85°C 28 Thin QFN
MAX1538
Power-Source Selector for
Dual-Battery Systems
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
BATA
= V
BATB
= V
CHGIN
= 16.8V, C
VDD
= 1µF, V
MINVA
= V
MINVB
= 0.93V, V
EXTLD
= V
ADPIN
= 28V, V
CHRG
= V
BATSEL
= V
RELRN
= 0,
C
ADPPWR
= C
REVBLK
= C
ADPBLK
= C
DISBAT
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= 4.7nF, TA = 0°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +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.
V
EXTLD
, V
BATSUP
, V
ADPIN
, V
BATA
, V
BATB
,
V
CHGIN
to GND .................................................-0.3V to +30V
V
ADPPWR
to GND...................................-0.3V to (V
ADPIN
+ 0.3V)
V
REVBLK
, V
ADPBLK
to GND ...................-0.3V to (V
EXTLD
+ 0.3V)
V
CHGA
, V
CHGB, VDISBAT
to GND ..........-0.3V to (V
CHGIN
+ 0.3V)
V
DISA
to GND..........................................-0.3V to (V
BATA
+ 0.3V)
V
DISB
to GND..........................................-0.3V to (V
BATB
+ 0.3V)
V
DD
, V
CHRG
, V
BATSEL
, V
RELRN
, V
OUT0
, V
OUT1
, V
OUT2
,
V
MINVA
, V
MINVB
, V
AIRDET
, V
ACDET
to GND..........-0.3V to +6V
Continuous Power Dissipation (T
A
= +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
PARAMETER CONDITIONS
MIN
TYP
MAX
UNITS
ADPIN, EXTLD Supply Voltage
Range
V
CHGIN, BATA, BATB and
BATSUP Supply Voltage Range
V
V
ADPIN
= highest,
V
ADPPWR
= high
21 50
V
ADPIN
= highest,
V
ADPPWR
= low
23 54
V
BATA
= highest,
V
DISA
= high
21 42
24 50
V
BATB
= highest,
V
DISB
= high
21 42
24 50
ADPIN, BATA, BATB, BATSUP
Quiescent Current (Current from
the Highest Voltage Supply)
V
BATA
= 4.75V to 19V,
V
BATB
= 4.75V to 19V,
V
ADPIN
= 4.75V to 28V,
no external load at V
DD
V
BATSUP
= highest 18 40
µA
V
ADPPWR
= high
0.5
ADPIN Quiescent Current (ADPIN
Current When Not the Highest
Voltage)
V
ADPIN
= 4.75V to 18V,
no external load at V
DD
V
ADPPWR
= low 2.6 6
µA
V
DISA
= high 3.9 6.0
BATA Quiescent Current (BATA
Current When Not the Highest
Voltage)
V
BATA
= 4.75V to 19V,
no external load at V
DD
V
DISA
= low 7.0 12
µA
V
DISB
= high 3.9 6.0
BATB Quiescent Current (BATB
Current When Not the Highest
Voltage)
V
BATB
= 4.75V to 19V,
no external load at V
DD
V
DISB
= low 7.0 12
µA
Adapter selected (REVBLK or ADPBLK pins low) 3.0 6.1
EXTLD Quiescent Current
Adapter not selected (REVBLK and ADPBLK pins high)
1.0
µA
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
3.1 6.2
CHGIN Quiescent Current
Discharge or relearn state (CHGA or CHGB pin low,
DISBAT pin low)
6.1
µA
4.75 28.00
4.75 19.00
V
BATSUP
= 4.75V to 19V,
V
V
BATA
BATB
= highest, V
= highest, V
DISA
DISB
= low
= low
Charge state (CHGA or CHGB pin low, DISBAT pin high)
0.01
0.02
0.03
12.1
MAX1538
Power-Source Selector for
Dual-Battery Systems
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
BATA
= V
BATB
= V
CHGIN
= 16.8V, C
VDD
= 1µF, V
MINVA
= V
MINVB
= 0.93V, V
EXTLD
= V
ADPIN
= 28V, V
CHRG
= V
BATSEL
= V
RELRN
= 0,
C
ADPPWR
= C
REVBLK
= C
ADPBLK
= C
DISBAT
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= 4.7nF, TA = 0°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C.)
PARAMETER CONDITIONS
UNITS
LINEAR REGULATOR
VDD Output Voltage I
VDD
= 0 to 100µA
3.3
V
V
BATA
or V
BATB
= 5V to 19V, V
ADPIN
= 5V 1.0
V
BATA
= V
BATB
= 5V, V
ADPIN
= 5V to 28V 1.0
VDD Power-Supply Rejection
Ratio
V
BATA
, V
BATB
, or V
ADPIN
= 5V to 19V, sawtooth at
10V/µs, other supplies = 12V
1
mV / V
VDD Undervoltage Lockout Rising edge, relative to regulation point -55 -10 mV
COMPARATORS
ACDET, AIRDET Input Voltage
Range
0 5.5 V
ACDET, AIRDET Input Bias
Current
V
AIRDET
= V
ACDET
= 3V 0.1 1 µA
ACDET, AIRDET Trip Threshold Input falling
2.0
V
ACDET, AIRDET Hysteresis 20 mV
MINV_ Operating Voltage Range
V
MINV_ Input Bias Current V
MINV_
= 0.93V to 2.6V -50
nA
V
MINV_
= 0.93V
V
MINV_
= 1.5V
7.5
BAT_ Minimum Voltage Trip
Threshold
V
BAT_
falling
V
MINV_
= 2.6V
13
V
BAT_ Minimum Voltage
Hysteresis
mV
BAT_ Pack Removal Detection
Threshold
V
BAT_
falling
2.0
V
BAT_ Pack Removal Hysteresis 85 mV
GATE DRIVERS (Note 1)
V
SOURCE
= 15V, V
PIN
= 7.5V 18 60
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Source Current (PMOS
Turn-Off)
V
SOURCE
= 15V, V
PIN
= 13V 3 15
mA
V
SOURCE
= 15V, V
PIN
= 15V 20 70
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Sink Current (PMOS
Turn-On)
V
SOURCE
= 15V, V
PIN
= 9.5V 10 55
mA
V
SOURCE
= 8V to 28V)
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-On Clamp Voltage
(V
PIN
to V
SOURCE
)
V
SOURCE
= 4.75V to 8V
V
MIN TYP MAX
3.270
1.97
0.93 2.60
4.605 4.65 4.695
7.455
12.93
1.90
V
= 8V to 19V (ADPPWR, REVBLK, and AOPBLK,
SOURCE
-11.0 -9.0 -7.0
-8.00 -3.65
125
3.330
2.03
+50
7.545
13.07
2.10
MAX1538
Power-Source Selector for
Dual-Battery Systems
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(V
BATA
= V
BATB
= V
CHGIN
= 16.8V, C
VDD
= 1µF, V
MINVA
= V
MINVB
= 0.93V, V
EXTLD
= V
ADPIN
= 28V, V
CHRG
= V
BATSEL
= V
RELRN
= 0,
C
ADPPWR
= C
REVBLK
= C
ADPBLK
= C
DISBAT
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= 4.7nF, TA = 0°C to +85°C, unless otherwise noted.
Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-On Time
0.3
µs
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-Off Time
0.3
µs
STATE SELECTION INPUTS
CHRG, BATSEL, RELRN Input
Low Voltage
0.8 V
CHRG, BATSEL, RELRN Input
High Voltage
2.1 V
CHRG, BATSEL, RELRN Input
Leakage Current
V
CHRG
= V
BATSEL
= V
RELRN
= 5.5V 0.1 1 µA
STATE OUTPUTS
V
OUT_
= 0.4V 1
OUT0, OUT1, OUT2 Sink Current
V
OUT_
= 5.5V 25
mA
OUT0, OUT1, OUT2 Leakage
Current
0.1 1 µA
TRANSITION TIMES
MINV_ Comparator Delay t
MINV
V
BAT
_ = 5.5V to V
BAT
_ = 4.45V 5.5 11 µs
AIRDET and ACDET Comparator
Delay
t
ADP
Falling edge with -20mV overdrive 2.7 6.0 µs
BAT_ Removal Comparator Delay
Falling edge with -20mV overdrive 10 µs
Battery-Insertion Blanking Time t
BBLANK
13 21 31 ms
State-Machine Delay 50 ns
MOSFET Turn-On Delay t
TRANS
5 7.5 10 µs
V
OU T _
V
V
= 5.5V
SOURCE
SOURCE
= 15V, V
= 15V, V
= 13V to V
PIN
= 9V to V
PIN
PIN
PIN
= 9V
= 13V
0.88
0.88
MAX1538
Power-Source Selector for
Dual-Battery Systems
_______________________________________________________________________________________ 5
ELECTRICAL CHARACTERISTICS
(V
BATA
= V
BATB
= V
CHGIN
= 16.8V, C
VDD
= 1µF, V
MINVA
= V
MINVB
= 0.93V, V
EXTLD
= V
ADPIN
= 28V, V
CHRG
= V
BATSEL
= V
RELRN
= 0,
C
ADPPWR
= C
REVBLK
= C
ADPBLK
= C
DISBAT
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= 4.7nF, TA = -40°C to +85°C, unless otherwise noted.)
(Note 2)
PARAMETER CONDITIONS
UNITS
ADPIN, EXTLD Supply Voltage
Range
V
CHGIN, BATA, BATB, and
BATSUP Supply Voltage Range
V
V
ADPIN
= highest,
V
ADPPWR
= high
50
V
ADPIN
= highest,
V
ADPPWR
= low
54
42
50
42
50
ADPIN, BATA, BATB, BATSUP
Quiescent Current (Current from
the Highest Voltage Supply)
V
B AT A
= 4.75V to 19V ,
V
B AT B
= 4.75V to 19V ,
V
A D P IN
= 4.75V to 28V ,
no exter nal l oad at V
D D
V
BATSUP
= highest 40
µA
V
ADPPWR
= high 1
ADPIN Quiescent Current (ADPIN
Current When Not the Highest
Voltage)
V
ADPPWR
= low 9
µA
V
DISA
= high 7.5
BATA Quiescent Current (BATA
Current When Not the Highest
Voltage)
V
BATA
= 4.75V to 19V,
V
DISA
= low 16
µA
V
DISB
= high 7.5
BATB Quiescent Current (BATB
Current When Not the Highest
Voltage)
V
BATB
= 4.75V to 19V,
V
DISB
= low 16
µA
Adapter selected (REVBLK or ADPBLK pins low) 9.5
EXTLD Quiescent Current
Adapter not selected (REVBLK and ADPBLK pins high) 1.0
µA
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
10
CHGIN Quiescent Current
Discharge or relearn state (CHGA or CHGB pin low,
DISBAT pin low)
µA
LINEAR REGULATOR
VDD Output Voltage I
VDD
= 0 to 100µA
V
VDD Undervoltage Lockout Rising edge, relative to regulation point -60 -10 mV
COMPARATORS
ACDET, AIRDET Input Voltage
Range
0 5.5 V
ACDET, AIRDET Trip Threshold Input falling
V
MINV_ Operating Voltage Range
V
V
MINV_
= 0.93V
V
MINV_
= 1.5V 7.4 7.6
BAT_ Minimum Voltage Trip
Threshold
V
BAT_
falling
V
MINV_
= 2.6V
V
MIN MAX
4.75 28.00
4.75 19.00
V
B AT S U P
V
ADPIN
no external load at V
no external load at V
no external load at V
Charge state (CHGA or CHGB pin low, DISBAT pin high)
= 4.75V to 19V ,
= 4.75V to 18V,
= highest, V
BATA
V
= highest, V
BATA
V
= highest, V
BATB
V
BATB
= highest, V
DD
DD
DD
DISA
DISA
DISB
DISB
= high
= low
= high
= low
V
3.270 3.330
1.94 2.06
0.93 2.60
4.59 4.72
12.86 13.14
18.5
MAX1538
Power-Source Selector for
Dual-Battery Systems
6 _______________________________________________________________________________________
PARAMETER
CONDITIONS
UNITS
BAT_ Pack Removal Detection
Threshold
V
BAT_
falling
V
GATE DRIVERS (Note 1)
V
SOURCE
= 15V, V
PIN
= 7.5V 18
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Source Current (PMOS
Turn-Off)
V
SOURCE
= 15V, V
PIN
= 13V 3
mA
V
SOURCE
= 15V, V
PIN
= 15V 20
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Sink Current (PMOS
Turn-On)
V
SOURCE
= 15V, V
PIN
= 9.5V 10
mA
V
S 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 )
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-On Clamp Voltage
(V
PIN
to V
SOURCE
)
V
SOURCE
= 4.75V to 8V
V
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-On Time
µs
ADPPWR, REVBLK, ADPBLK,
DISBAT, DISA, DISB, CHGA,
CHGB Turn-Off Time
µs
STATE SELECTION INPUTS
CHRG, BATSEL, RELRN Input
Low Voltage
0.8 V
CHRG, BATSEL, RELRN Input
High Voltage
2.1 V
STATE OUTPUTS
1
25
mA
TRANSITION TIMES
MINV_ Comparator Delay t
MINV
V
BAT
_ = 5.5V to V
BAT
_ = 4.45V 11 µs
AIRDET and ACDET Comparator
Delay
t
ADP
Falling edge with -20mV overdrive 6 µs
Battery-Insertion Blanking Time t
BBLANK
12 31 ms
MOSFET Turn-On Delay t
TRANS
510µs
Note 1: V
PIN
refers to the voltage of the driver output. V
SOURCE
refers to the power source for the driver. ADPPWR, REVBLK, ADPBLK, 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)
(V
BATA
= V
BATB
= V
CHGIN
= 16.8V, C
VDD
= 1µF, V
MINVA
= V
MINVB
= 0.93V, V
EXTLD
= V
ADPIN
= 28V, V
CHRG
= V
BATSEL
= V
RELRN
= 0,
C
ADPPWR
= C
REVBLK
= C
ADPBLK
= C
DISBAT
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= 4.7nF, TA = -40°C to +85°C, unless otherwise noted.)
(Note 2)
SYMBOL
MIN MAX
1.88 2.12
OUT0, OUT1, OUT2 Sink Current
-11.7 -6.5
-8.00 -3.50
V
OU T _
V
OU T _
V
V
= 15V, V
SOURCE
= 15V, V
SOURCE
= 0.4V
= 5.5V
= 13V to V
PIN
= 9V to V
PIN
= 9V 0.88
PIN
= 13V 0.88
PIN
MAX1538
Power-Source Selector for
Dual-Battery Systems
_______________________________________________________________________________________ 7
VDD LOAD REGULATION
MAX1538 toc01
VDD LOAD CURRENT (mA)
V
DD
(V)
0.150.100.05
3.291
3.292
3.293
3.294
3.295
3.296
3.297
3.298
3.299
3.290
00.20
VDD vs. TEMPERATURE
MAX1538 toc02
TEMPERATURE (°C)
V
DD
(V)
6040200-20
3.290
3.295
3.300
3.305
3.310
3.285
-40 80
I
BAT_
vs. V
BAT_
MAX1538 toc04
BATTERY VOLTAGE (V)
BATTERY INPUT CURRENT (µA)
15105
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
020
BAT_ NOT HIGHEST SUPPLY
I
BAT_
vs. V
BAT_
MAX1538 toc03
BATTERY VOLTAGE (V)
BATTERY INPUT CURRENT (µA)
14121086
5
10
15
20
25
30
35
0
416
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
V
ADPIN
AND
V
EXTLD
V
ADPBLK
V
REVBLK
V
OUT1
0V
20V
10V
0V
5V
0V
V
ADPIN
V
EXTLD
V
REVBLK
V
ADPBLK
t
ADP
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