19-2455; Rev 0; 4/02
Li+ Battery-Pack Protector with
Integrated Fuse Driver
General Description
The MAX1906 protects against overvoltage conditions
in lithium-ion/lithium polymer (Li+) battery packs by
blowing a three-terminal protection fuse. The IC should
be used in conjunction with resettable protection cir-
cuits to provide a high level of safety against over-
charging Li+ batteries. It can be used with 2-, 3-, or
4-series cell battery packs.
The MAX1906 monitors individual cell voltages. If any
cell voltage exceeds the overvoltage threshold for
greater than 2.1s, the MAX1906 activates an internal
SCR. The SCR sinks sufficient current to blow an exter-
nal protection fuse, permanently disabling the battery
pack. Alternatively, the IC can drive the gate of an
external MOSFET to blow the fuse.
The MAX1906 also offers protection against disconnect-
ed voltage sense pins. If a disconnected pin is detected,
the DISCON output is forced low. The MAX1906 includes
a test mode, which determines if the circuit is operating
correctly while in an assembled battery pack.
The low-cost MAX1906 is available in a thermally
enhanced 16-pin QFN package.
o
Protects Against Overvoltage
o
±1% Accurate Protection Thresholds
o
Integrated 2.1s Fault-Delay Timer
o
Built-in 1.5A SCR Fuse Driver
o
Test Mode for Functional Verification in
Assembled Pack
o
8µA (max) Supply Current
o
1µA (max) Standby Current
o
Protects Against Disconnected B1P–B4P Pins
o
Protects 2-, 3-, or 4-Series Li+ Battery Packs
o
Available in Small 16-Pin QFN Package
(5mm x 5mm)
Features
MAX1906
Ordering Information
PART
TEMP RANGE
MAX1906SEGE -40°C to +85°C
MAX1906VEGE -40°C to +85°C
MAX1906XEGE -40°C to +85°C
PIN-PACKAGE
CELLS
16 QFN 5mm
✕
5mm
2
16 QFN 5mm
✕
5mm
3
16 QFN 5mm
✕
5mm
4
Applications
2-, 3-, or 4-Series Li+ Battery Packs for
Portable Products
Minimal Operating Circuit
I.C. (B4P)
FUSE
PACK+
VCC
7
OUT
B4P
16
Pin Configuration
I.C. [B3P]
14
N.C.
N.C.
13
12
11
B2P
N.C.
B1P
I.C.
10
9
8
BN
16
I.C.
4
DISCON
B3P
14
15
1
2
3
4
5
PKN
6
N.C.
7
OUT
DRV
12
OPTIONAL
PACK
CONTROLLER
2
DRV
MAX1906X
B2P
TEST
DISCON
MAX1906S/V/X
3
TEST
5
B1P
10
PKN
BN
8
5mm x 5mm QFN
PACK-
[]:MAX1906V, MAX1906X
():MAX1906X
________________________________________________________________
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.
Li+ Battery-Pack Protector with
Integrated Fuse Driver
MAX1906
ABSOLUTE MAXIMUM RATINGS
B4P to BN ...............................................................-0.3V to +24V
B3P to BN ...............................................................-0.3V to +18V
B2P to BN ...............................................................-0.3V to +12V
B4P to B3P, B3P to B2P, B2P to B1P, B1P to BN ....-0.3V to +6V
TEST, DRV, DISCON to PKN ....................................-0.3V to +6V
OUT to BN ..............................................................-0.3V to +24V
BN to PKN ...................................................................-2V to +2V
OUT Maximum Current .........................................................2.5A
Continuous Power Dissipation (T
A
= +70°C, per JEDEC JESD51-7)
16-Pin QFN (derate 19mW/°C above +70°C ambient) ....1.5W
Operating Temperature Ranges..........................-40°C to +85°C
Storage Temperature.........................................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(T
A
= 0°C to +85°C,
individual cell voltages = 4.2V unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
B4P Voltage Range
B3P Voltage Range
B2P Voltage Range
B1P Voltage Range
Overvoltage Detection Threshold
Overvoltage Detection Threshold,
Test Mode
Overvoltage Detection Hysteresis
SCR Release Threshold
Standby-Mode Threshold
Overvoltage Delay
Sampling Interval
Supply Current
Supply Current During Sampling
Standby Current
Intermediate Cell
Quiescent Current
OUT Output Sink Current
OUT Voltage
(when SCR Is Triggered)
OUT Leakage Current
DRV Output Voltage Low
DRV Output Voltage High
DRV Sink Current
DRV Source Current
Test-Mode Delay
Test-Mode Output Duration
DISCON Output Voltage Low
DISCON Leakage Current
V
DRVL
V
DRVH
I
DRV
I
DRV
t
DLY
t
OUT
Individual cell voltages = 2.2V
(Note 3)
OUT = 2V, current not internally limited
I
OUT
= 1.5A
OUT = 24V
I
DRV
= 200µA
I
DRV
= 5µA
I
DRV
= -1mA
V
DRVH
= 2.5V
V
DRVL
= 0V
(Note 4)
(Note 4)
I
DISCON
= 1mA
V
DISCON
= 3.3V
-1
100
130
4.0
2.0
2
2
1.2
160
0.4
+1
4.8
4.8
-1
1.0
0.5
1.5
1.6
2.0
2.0
+1
0.4
5.5
5.5
I
SUP
t
OV
(Note 1)
(Note 2)
V
OV_HYS
V
REL
V
OV_TH
Cell voltage rising
Cell voltage rising, test mode
Cell voltage falling
Cell voltage falling
Cell voltage falling
3.85
2.3
1.85
4.4
2.0
4.45
2.225
10
4.0
3.3
2.1
2.56
3
300
800
6
4.15
4.1
2.45
SYMBOL
CONDITIONS
MIN
TYP
MAX
20
15
10
5
4.5
2.4
UNITS
V
V
V
V
V
V
mV
V
V
s
s
µA
µA
nA
nA
A
V
µA
V
V
mA
mA
ms
ms
V
µA
2
_______________________________________________________________________________________
Li+ Battery-Pack Protector with
Integrated Fuse Driver
ELECTRICAL CHARACTERISTICS (continued)
(T
A
= 0°C to +85°C,
individual cell voltages = 4.2V unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Disconnected Pin Test Time
TEST Input High
Minimum TEST High Duration
TEST Input Low
TEST Pulldown to PKN
Thermal Impedance,
Junction to Case
17
5
SYMBOL
CONDITIONS
Test time per cell
2.2
50
0.8
33
MIN
TYP
0.2
MAX
UNITS
ms
V
µs
V
kΩ
°C/W
MAX1906
ELECTRICAL CHARACTERISTICS
(T
A
= -40°C to +85°C,
individual cell voltages = 4.2V, unless otherwise noted.)
PARAMETER
B4P Voltage Range
B3P Voltage Range
B2P Voltage Range
B1P Voltage Range
Overvoltage Detection Threshold
Overvoltage Detection Threshold,
Test Mode
SCR Release Threshold
Standby Mode Threshold
Overvoltage Delay
Supply Current
Standby Current
OUT Output Sink Current
OUT Voltage
(when SCR Is Triggered)
DRV Output Voltage Low
DRV Output Voltage High
DRV Output Voltage High
DRV Sink Current
DRV Source Current
Test-Mode Delay
Test-Mode Output Duration
DISCON Output Voltage Low
TEST Input High
TEST Input Low
TEST Pulldown to PKN
17
V
DRVL
V
DRVH
V
DRVH
I
DRV
I
DRV
t
DLY
t
OUT
t
OV
I
SUP
(Note 2)
Individual cell voltages = 2.2V
OUT = 2V, current not internally limited
I
OUT
= 1.5A
I
DRV
= 200µA
I
DRV
= 5µA
I
DRV
= -1mA
V
DRVH
= 2.5V
V
DRVL
= 0V
(Note 4)
(Note 4)
I
DISCON
= 1mA
2.6
0.8
33
95
3.9
2.0
2
2
1.25
165
0.4
1.0
2.2
0.4
5.5
5.5
V
REL
V
OV_TH
Cell voltage rising
Cell voltage rising, test mode
Cell voltage falling
Cell voltage falling
4.35
1.95
3.80
2.25
1.85
SYMBOL
CONDITIONS
MIN
TYP
MAX
20
15
10
5
4.55
2.45
4.2
4.15
2.45
8
1
UNITS
V
V
V
V
V
V
V
V
s
µA
µA
A
V
V
V
V
mA
mA
ms
ms
V
V
V
kΩ
Note 1:
Note 2:
Note 3:
Note 4:
See the
Normal Operating Mode
section.
The supply current is measured at the top cell and averaged over one sampling interval.
Guaranteed by design.
See Figure 7.
_______________________________________________________________________________________
3
Li+ Battery-Pack Protector with
Integrated Fuse Driver
MAX1906
Typical Operating Characteristics
(T
A
= +25°C, unless otherwise noted.)
OVERVOLTAGE THRESHOLD
vs. TEMPERATURE
MAX1906 toc01
STANDBY-MODE THRESHOLD
vs. TEMPERATURE
MAX1906 toc02
SUPPLY CURRENT
vs. TEMPERATURE
MAX1906 toc03
4.455
3.5
3.3
CELL VOLTAGE (V)
3.1
2.9
2.7
2.5
EQUAL VOLTAGE APPLIED
TO ALL CELL INPUTS (FALLING)
4.5
4.3
SUPPLY CURRENT (µA)
CELL VOLTAGE (V)
4.450
4.1
3.9
4.445
3.7
4.440
-40
-15
10
35
60
85
TEMPERATURE (°C)
2.3
-40
-15
10
35
60
85
TEMPERATURE (°C)
3.5
-40
-15
10
35
60
85
TEMPERATURE (°C)
STANDBY CURRENT
vs. TEMPERATURE
MAX1906 toc04
THERMAL IMPEDANCE, CASE-TO-AMBIENT
vs. COPPER AREA
MAX1906 toc05
TIME-TO-MAX JUNCTION TEMPERATURE
vs. POWER DISSIPATION
T
A
= +60°C
1000
TIME (s)
MAX1906 toc06
0.70
80
1oz COPPER
10,000
STANDBY CURRENT (µA)
0.68
0.66
R
θCA
(°C/W)
60
100
0.25in
2
0.50in
2
0.64
40
0.62
10
0.04in
2
20
-40
-15
10
35
60
85
0.01
0.1
1
10
TEMPERATURE (°C)
COPPER AREA (in
2
)
1
1.0
1.5
2.0
2.5
3.0
POWER DISSIPATION (W)
0.60
INSTANTANEOUS ON-STATE VOLTAGE
vs. CURRENT
INSTANTANEOUS ON-STATE CURRENT (A)
MAX1906 toc07
TEST-MODE TIMING
MAX1906 toc08
1.6
1.3
TEST PIN
VOLTAGE
5V/div
1.0
110°C
0.7
T
J
= 25°C
0.4
DRV PIN
VOLTAGE
5V/div
DISCON PIN
VOLTAGE
5V/div
0.8
1.0
1.2
1.4
1.6
1.8
20ms/div
0.1
INSTANTANEOUS ON-STATE VOLTAGE (V)
4
_______________________________________________________________________________________
Li+ Battery-Pack Protector with
Integrated Fuse Driver
Pin Description
PIN
MAX1906S
1, 9
MAX1906V
1, 9
MAX1906X
1, 9
NAME
I.C.
N.C.
DRV
DESCRIPTION
Internal Connection. Float pins 1 and 9.
No Connection
MOSFET Driver Output. High when an overvoltage condition is detected.
Connect the DRV pin to the gate of an external MOSFET to blow the
protection fuse.
Test-Mode Input. Test mode is enabled with a pulse of minimum 50µs
duration on the TEST pin.
Disconnected Pin Output. This is an open-drain output and is high-Z during
normal operation. If B4P, B3P, B2P, or B1P is disconnected, this pin is
pulled low (see the
Disconnected Pin Detection
section).
Pack Negative. A sense resistor may be connected between BN and PKN.
Anode Output of the SCR. Connect OUT to the fuse’s heater connection (see
the
Protection Fuse Selection
section).
Negative Terminal of Cell 1. Connect BN to the negative terminal of the first
series Li+ cell. BN is also chip ground, which is connected to the backside
paddle on the QFN package.
Positive Terminal of Cell 1. Connect B1P to the positive terminal of the first
series Li+ cell.
Positive Terminal of Cell 2. Connect B2P to the positive terminal of the
second series Li+ cell.
Positive Terminal of Cell 3. Connect B3P to the positive terminal of the third
series Li+ cell.
Positive Terminal of Cell 4. Connect B4P to the positive terminal of the fourth
series Li+ cell.
MAX1906
6, 11, 13, 15 6, 11, 13, 15 6, 11, 13, 15
2
2
2
3
3
3
TEST
4
5
7
4
5
7
4
5
7
DISCON
PKN
OUT
8
8
8
BN
10
12
—
—
10
12
14
—
10
12
14
16
B1P
B2P
B3P
B4P
Detailed Description
The MAX1906 protects 2-, 3-, or 4-series Li+ battery
packs from overcharge by controlling a three-terminal
protection fuse. Figures 1 and 2 show two application
circuits using the MAX1906. The MAX1906 checks the
voltage of each cell at regular intervals. An overcharge
condition is detected if any cell voltage exceeds the
overvoltage threshold for more than 2.1s. The MAX1906
responds to an overcharge condition by turning on an
internal SCR (Figure 1) or an external MOSFET (Figure 2)
to blow a three-terminal protection fuse placed in series
with the charging path.
The MAX1906 checks for disconnected voltage sense
pins every time it exits the standby mode or test mode. If
a disconnected pin is detected, the DISCON pin is
latched low. The MAX1906 also includes a test mode,
which determines if the circuit is operating correctly while
in an assembled battery pack. A pulse on the TEST pin
enables the test mode. Figure 3 shows the cell connec-
tions for 2- and 3-series battery packs and Figure 4
shows the functional diagram for the MAX1906.
The MAX1906 can be used together with other
resettable protection circuits to provide a high level of
safety against overcharging Li+ batteries. Figure 5 shows
a typical application circuit using the MAX1906 together
with the MAX1924. The MAX1924 has a lower overvoltage
threshold than the MAX1906. If any cell voltage exceeds
4.35V (typ), the MAX1924 turns off the
TKO
and
CGO
MOSFETs and opens the charging path. If the
TKO
or
CGO
MOSFET fails and charging continues, the
MAX1906 blows the protection fuse and opens the charg-
ing path permanently once any cell voltage reaches
4.45V (typ). The MAX1924 also protects the battery pack
against undervoltage, charge current, discharge current,
and pack-short fault conditions. Refer to the MAX1894/
MAX1924 data sheets for complete details.
5
_______________________________________________________________________________________
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