19-1796; Rev 1; 1/03
KIT
ATION
EVALU
BLE
AVAILA
Power Source Selector for
Dual-Battery Systems
Features
o
Patented
†
7-MOSFET Topology Offers Low-Cost
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 µP Firmware
o
Extends Battery Life by Allowing Power
Management µP 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
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 bat-
tery 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 prob-
lem. The MAX1773/MAX1773A provide most of the power
source monitoring and selection, freeing the system power
management microprocessor (µP) for other tasks. This not
only simplifies development of the power management
firmware for the µP but also allows the µP to enter standby,
thereby reducing system power consumption.
The MAX1773A is recommended for new designs.
MAX1773/MAX1773A
Ordering Information
PART
MAX1773EUP
MAX1773AEUP
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
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
µP
BATSEL
V
DD
MINV
3.3V
SYSTEM LOGIC SUPPLY
TO HOST
µP
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
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Power Source Selector for
Dual-Battery Systems
MAX1773/MAX1773A
ABSOLUTE MAXIMUM RATINGS
V
BATA
, V
BATB
to GND ............................................-0.3V to +20V
V
COMA
to GND........................................-0.3V to (V
BATA
+ 0.3V)
V
COMB
to GND........................................-0.3V to (V
BATB
+ 0.3V)
V
CHGA
, V
CHGB
, V
EXTLD
, V
ACDET
to GND ..............-0.3V to +30V
V
PDS
, V
DISA
, V
DISB
to GND ...................-0.3V to (V
EXTLD
+ 0.3V)
V
DD
, V
BATSEL
, V
ACPRES
, V
BATSTAT
, V
TCOMP
,
V
MINV
to GND.......................................................-0.3V to +6V
V
THMA,
V
THMB
(Note 1)............................................ -0.3V to +6V
Continuous Current out of THMA, THMB............................20mA
I
ACPRES
, I
BATSTAT
Sink Current..........................................30mA
Continuous Power Dissipation (T
A
= +70°C)
20-Pin TSSOP (derate 7.0mW/°C above +70°C) ........560mW
Operating Temperature ......................................-40°C to +85°C
Storage Temperature ........................................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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
(V
BATA
= V
BATB
= 16.8V, C
VDD
= 3.3µF, V
MINV
= 0.93V, V
EXTLD
= V
ACDET
= 28V, V
TCOMP
= 3V, V
THMA
= V
THMB
= 1.65V,
V
BATSEL
= 0, C
COMA
= C
COMB
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= C
PDS
= 5nF,
T
A
= 0°C to +85°C,
unless otherwise noted.)
PARAMETER
EXTLD Supply Voltage Range
BATA, BATB Supply Voltage Range
BATA, BATB Quiescent Current
(Current from the higher voltage supply)
V
BATA
= 4.75V to 19V,
V
BATB
= 4.75V to 19V,
I
VDD
= 0
V
BATA
= 4.75V to 19V,
V
BATB
= 4.75V to 19V,
I
VDD
= 0
V
ACDET
= 28V
V
ACDET
= 2.2V to
V
BATA
and V
BATB
V
ACDET
= 28V
V
ACDET
= 2.2V to
V
BATA
and V
BATB
CONDITIONS
V
EXTLD
> V
BATA
and V
BATB
MIN
4.75
4.75
5
40
5
8
35
5
TYP
MAX
28.00
19.00
8
70
8
13
55
8
µA
µA
µA
UNITS
V
V
BATA, BATB Quiescent Current
(Current from the lower voltage supply)
V
ACDET
= 28V, V
EXTLD
= 28V
EXTLD Quiescent Current
LINEAR REGULATOR
V
DD
Output Voltage
I
VDD
= 0 to 100µA
I
VDD
= 100µA to 1mA
V
BATA
or V
BATB
= 5V to 19V, V
EXTLD
= 5V
V
DD
Power-Supply Rejection Ratio
V
BATA
= V
BATB
= 5V, V
EXTLD
= 5V to 28V
V
BATA
, V
BATB
, or V
EXTLD
= 5V to 19V,
sawtooth at 10V/µs, other supplies = 12V
Hysteresis is typically 50mV
(Note 2)
V
THM
_ = 5.5V
V
THMA
= V
THMB
= 0 to 5.5V
TCOMP Input Voltage Range
V
THMA
= V
THMB
= 0 to 5.5V, V
BATA
= V
BATB
= V
EXTLD
= 4.75V
0
0
2.0
0
0
3.234
3.168
V
ACDET
= 2.2V to V
BATA
and V
BATB,
V
EXTLD
= 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
V
DD
Undervoltage Lockout
COMPARATORS
TCOMP Undervoltage Lockout
THM_ Input Voltage Range
THM_ Input Leakage Current
2
_______________________________________________________________________________________
Power Source Selector for
Dual-Battery Systems
MAX1773/MAX1773A
ELECTRICAL CHARACTERISTICS (continued)
(V
BATA
= V
BATB
= 16.8V, C
VDD
= 3.3µF, V
MINV
= 0.93V, V
EXTLD
= V
ACDET
= 28V, V
TCOMP
= 3V, V
THMA
= V
THMB
= 1.65V,
V
BATSEL
= 0, C
COMA
= C
COMB
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= C
PDS
= 5nF,
T
A
= 0°C to +85°C,
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
V
ACDET
= 3V, V
ACDET
< V
BATA
and V
BATB
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
(V
COM
_ to V
BAT
_)
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)
V
BAT
_ = 16.8V, V
COM
_ = 14.8V
V
BAT
_ = 16.8V, V
COM
_ = 16.4V
V
BAT
_ = 16.8V, V
COM
_ = 14.8V
V
COM
_ = 11.8V, V
BAT
_ = 16.8V (Note 4)
V
BAT
_ = 8V to 19V
V
BAT
_ = 4.75V to 8V
V
PDS
= 10V, V
EXTLD
= 12V
V
PDS
= 2V to 28V
V
PDS
= 28V
V
CHG
_ = 2V to 22V
V
CHG
_ = 28V
V
EXTLD
= 15V, V
DIS
_ = 13V
V
EXTLD
= 15V, V
DIS
_ = 14.6V
V
EXTLD
= 15V, V
DIS
_ = 13V
V
EXTLD
= 16.8V, V
DIS
_ = 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
µA
mA
V
mA
mA
µA
mA
µA
mA
µA
mA
V
BATSEL
= 5.5V
20
V
BATA
= V
BATB
= 5
×
V
MINV
V
MINV
= 0.93V to 2.6V
V
BAT
_ falling
V
MINV
= 0.93V
V
MINV
= 2.6V
V
ACDET
falling with respect to V
BATB
V
ACDET
= 3V, V
ACDET
< V
BATB
, V
BATA
= 0
V
ACDET
= 28V, V
ACDET
> V
BATA
and V
BATB
V
ACDET
falling with respect to V
BATA
0
100
0
100
0.93
-100
4.55
12.7
2.0
1
100
4.65
13
(Note 3)
V
TCOMP
= 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
µA
µs
µA
50
28.0
CONDITIONS
MIN
TYP
0.1
MAX
100
+30
UNITS
nA
mV
mV
V
V
Typical hysteresis is 100mV
_______________________________________________________________________________________
3
Power Source Selector for
Dual-Battery Systems
MAX1773/MAX1773A
ELECTRICAL CHARACTERISTICS (continued)
(V
BATA
= V
BATB
= 16.8V, C
VDD
= 3.3µF, V
MINV
= 0.93V, V
EXTLD
= V
ACDET
= 28V, V
TCOMP
= 3V, V
THMA
= V
THMB
= 1.65V,
V
BATSEL
= 0, C
COMA
= C
COMB
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= C
PDS
= 5nF,
T
A
= 0°C to +85°C,
unless otherwise noted.)
PARAMETER
DIS_ Turn-On Clamp Voltage
(V
DIS
_
to V
EXTLD
)
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
V
ACDET
= 2.2V, V
MINV
= 0.93V (Note 6)
V
ACDET
= 2.2V, V
MINV
= 0.93V (Note 7)
V
ACDET
= 2.2V, V
MINV
= 0.93V (Note 8)
V
ACDET
= 2.2V, V
MINV
= 0.93V (Note 9)
V
ACDET
= 2.2V, V
MINV
= 0.93V (Note 10)
(Note 11)
130
300
5
260
12
10
260
530
µs
µs
µs
µs
µs
µs
V
ACPRES
= 0.4V
V
ACPRES
= 5.5V
V
BATSTAT
= 0.4V
V
BATSTAT
= 5.5V
V
ACPRES
= 5.5V
V
BATSTAT
= 5.5V
1
0.1
0.1
1
1
1
30
mA
mA
µA
µA
CONDITIONS
V
EXTLD
= 8V to 28V
V
EXTLD
= 4.75V to 8V
MIN
-11.5
-8.00
TYP
-9.5
MAX
-7.5
-4.25
UNITS
V
ELECTRICAL CHARACTERISTICS
(V
BATA
= V
BATB
= 16.8V, C
VDD
= 3.3µF, V
MINV
= 0.93V, V
EXTLD
= V
ACDET
= 28V, V
TCOMP
= 3V, V
THMA
= V
THMB
= 1.65V,
V
BATSEL
= 0, C
COMA
= C
COMB
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= C
PDS
= 5nF,
T
A
= -40°C to +85°C,
unless otherwise noted.)
PARAMETER
EXTLD Supply Voltage Range
BATA, BATB Supply Voltage Range
BATA, BATB Quiescent Current
(Current from the higher voltage supply)
V
BATA
= 4.75V to 19V, V
ACDET
= 28V
V
BATB
= 4.75V to 19V, V
ACDET
= 2.2V to
I
VDD
= 0
V
BATA
and V
BATB
V
BATA
= 4.75V to 19V, V
ACDET
= 28V
V
BATB
= 4.75V to 19V, V
ACDET
= 2.2V to
I
VDD
= 0
V
BATA
and V
BATB
V
ACDET
= 28V, V
EXTLD
= 28V
V
ACDET
= 2.2V to V
BATA
and V
BATB
, V
EXTLD
= 16V
I
VDD
= 0 to 100µA
I
VDD
= 100µA to 1mA
V
BATA
or V
BATB
= 5V to 19V, V
EXTLD
= 5V
V
BATA
= V
BATB
= 5V, V
EXTLD
= 5V to 28V
Hysteresis is typically 50mV
(Note 2)
2.0
0
3.234
3.168
CONDITIONS
V
EXTLD
> V
BATA
and V
BATB
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
µA
µA
UNITS
V
V
BATA, BATB Quiescent Current
(Current from the lower voltage supply)
EXTLD Quiescent Current
LINEAR REGULATOR
V
DD
Output Voltage
V
DD
Power-Supply Rejection Ratio
V
DD
Undervoltage Lockout
COMPARATORS
TCOMP Undervoltage Lockout
µA
V
mV/V
V
V
4
_______________________________________________________________________________________
Power Source Selector for
Dual-Battery Systems
ELECTRICAL CHARACTERISTICS (continued)
(V
BATA
= V
BATB
= 16.8V, C
VDD
= 3.3µF, V
MINV
= 0.93V, V
EXTLD
= V
ACDET
= 28V, V
TCOMP
= 3V, V
THMA
= V
THMB
= 1.65V,
V
BATSEL
= 0, C
COMA
= C
COMB
= C
DISA
= C
DISB
= C
CHGA
= C
CHGB
= C
PDS
= 5nF,
T
A
= -40°C to +85°C,
unless otherwise noted.)
PARAMETER
THM_ Input Voltage Range
THM_ Input Leakage Current
TCOMP Input Voltage Range
ACDET Operating Voltage Range
ACDET Logic Threshold High
V
ACDET
= 3V, V
ACDET
< V
BATA
and V
BATB
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
(V
COM
_ to V
BAT
_)
PDS Source Current (PMOS Turn-Off)
PDS Sink Current (PMOS Turn-On)
PDS Leakage Current (PMOS Off)
CHG_ Sink Current (PMOS Turn-On)
V
BAT
_ = 16.8V, V
COM
_ = 14.8V
V
BAT
_ = 16.8V, V
COM
_ = 16.4V
V
BAT
_ = 16.8V, V
COM
_ = 14.8V
V
COM
_ = 11.8V, V
BAT
_ = 16.8V (Note 4)
V
BAT
_ = 8V to 19V
V
BAT
_ = 4.75V to 8V
V
PDS
= 10V, V
EXTLD
= 12V
V
PDS
= 2V to 28V
V
PDS
= 28V
V
CHG
_ = 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
µA
mA
V
mA
mA
µA
mA
V
BATSEL
= 5.5V
20
V
BATA
= V
BATB
= 5
×
V
MINV
V
MINV
= 0.93V to 2.6V
V
BAT
_ falling
V
MINV
= 0.93V
V
MINV
= 2.6V
V
ACDET
falling with respect to V
BATB
V
ACDET
= 3V, V
ACDET
< V
BATB
, V
BATA
= 0
V
ACDET
= 28V, V
ACDET
> V
BATA
and V
BATB
V
ACDET
falling with respect to V
BATA
-35
100
-35
100
0.93
-100
4.55
12.7
2.0
1
100
V
THM_
= 5.5V
V
THMA
= V
THMB
= 0 to 5.5V
V
BATA
= V
BATB
= V
EXTLD
= 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
µA
µs
µA
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
_______________________________________________________________________________________
5
FPGA/CPLD
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