DS2762AX-025/T&R [MAXIM]
Power Supply Support Circuit, Fixed, 1 Channel, PBGA14, FLIPCHIP-14;
| 型号： | DS2762AX-025/T&R |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | Power Supply Support Circuit, Fixed, 1 Channel, PBGA14, FLIPCHIP-14 电池 监视器 |
| 文件： | 总25页 (文件大小：251K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
DS2762
High-Precision Li+ Battery Monitor With Alerts
www.maxim-ic.com
GENERAL DESCRIPTION
FEATURES
The DS2762 high-precision Li+ battery monitor is a
data-acquisition, information-storage, and safety-
protection device tailored for cost-sensitive battery
pack applications. This low-power device integrates
C
Li+ Safety Circuit
Overvoltage Protection
Overcurrent/Short-Circuit Protection
Undervoltage Protection
precise
temperature,
voltage,
and
current
C
Host Alerted When Accumulated Current or
Temperature Exceeds User-Selectable Limits
measurement, nonvolatile (NV) data storage, and Li+
protection into the small footprint of either a TSSOP
package or flip-chip package. The DS2762 is a key
component in applications including remaining
capacity estimation, safety monitoring, and battery-
specific data storage.
C
C
0V Battery Recovery Charge
Available in Two Configurations:
Internal 25mꢀ Sense Resistor
External User-Selectable Sense Resistor
C
Current Measurement
12-Bit Bidirectional Measurement
Internal Sense Resistor Configuration:
0.625mA LSB and ±1.9A Dynamic Range
External Sense Resistor Configuration:
15.625ꢁV LSB and ±64mV Dynamic Range
PIN CONFIGURATIONS
TOP VIEW
1
2
16
15
14
13
12
11
10
9
VIN
CC
PLS
DC
VDD
PIO
VSS
VSS
VSS
PS
C
Current Accumulation:
3
Internal Sense Resistor: 0.25mAhr LSB
External Sense Resistor: 6.25ꢁVhr LSB
SNS
SNS
SNS
DQ
4
5
6
7
8
C
C
Voltage Measurement with 4.88mV Resolution
Temperature Measurement Using Integrated
Sensor with 0.125°C Resolution
C
System Power Management and Control
Feature Support
IS2
IS1
TSSOP
C
C
C
32 Bytes of Lockable EEPROM
16 Bytes of General-Purpose SRAM
1
2
3
4
Dallas 1-Wire® Interface with Unique 64-Bit
Device Address
A
SNS
C
Low-Power Consumption:
B
C
D
PLS DC
DQ
Active Current: 60ꢁA typ, 90ꢁA max
Sleep Current: 1ꢁA typ, 2ꢁA max
SNS
CC
IS2
IS1
PROBE
APPLICATIONS
PDAs
VSS
VIN
PROBE
E
F
Cell Phones/Smartphones
Digital Cameras
VDD PIO
PS
VSS
FLIP CHIP
ORDERING INFORMATION
(top view – bumps on bottom)
PART
TEMP RANGE
PIN-PACKAGE
DS2762BE
-20°C to +70°C
16 TSSOP
Selector Guide appears at end of data sheet, for additional
options.
1-Wire is registered trademark of Dallas Semiconductor.
Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device
may be simultaneously available through various sales channels. For information about device errata, click here: www.maxim-ic.com/errata.
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REV: 111703
DS2762 High-Precision Li+ Battery Monitor With Alerts
ABSOLUTE MAXIMUM RATINGS
Voltage Range on PLS and CC Pin, Relative to VSS
Voltage Range on PIO Pin, Relative to VSS
Voltage Range on Any Other Pin, Relative to VSS
Continuous Internal Sense Resistor Current
Pulsed Internal Sense Resistor Current
Operating Temperature Range
-0.3V to +18V
-0.3V to +12V
-0.3V to +6V
M2.5A
M50A for <100µs/s, <1000 pulses
-40°C to +85°C
Storage Temperature Range
-55°C to +125°C
Soldering Temperature
See IPC/JEDEC J-STD-020A Specification
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 the absolute maximum rating conditions for extended periods may affect device.
RECOMMENDED DC OPERATING CONDITIONS
(2.5V ? VDD ? 5.5V, TA = -20°C to +70°C.)
PARAMETER
Supply Voltage
Data Pin
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
VDD
DQ
(Note 1)
(Note 1)
2.5
5.5
V
V
-0.3
+5.5
DC ELECTRICAL CHARACTERISTICS
(2.5V ? VDD ? 5.5V, TA = -20°C to +70°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Active Current
IACTIVE
DQ = VDD, normal operation
60
90
ꢀA
Sleep Mode Current
ISLEEP
VIH
DQ = 0V, no activity, PS floating
(Note 1)
1
2
ꢀA
V
Input Logic High: DQ, PIO
Input Logic High: PS
1.5
VIH
(Note 1)
VDD - 0.2V
V
Input Logic Low: DQ, PIO
Input Logic Low: PS
VIL
(Note 1)
0.4
0.2
V
VIL
(Note 1)
V
VOH
VOH
VOL
VOL
IPD
IOH = -0.1mA (Note 1)
IOH = -0.1mA (Note 1)
IOL = 0.1mA (Note 1)
IOL = 4mA (Note 1)
VPLS - 0.4V
VDD - 0.4V
V
Output Logic High: CC
Output Logic High: DC
Output Logic Low: CC, DC
Output Logic Low: DQ, PIO
DQ Pulldown Current
V
0.4
0.4
V
V
1
ꢀA
Mꢁ
mꢁ
s
Input Resistance: VIN
RIN
5
Internal Current-Sense Resistor
DQ Low to Sleep time
RSNS
tSLEEP
+25°C
20
2.1
25
30
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DS2762 High-Precision Li+ Battery Monitor With Alerts
ELECTRICAL CHARACTERISTICS: PROTECTION CIRCUITRY
(2.5V ? VDD ? 5.5V, TA = 0°C to +50°C.)
PARAMETER SYMBOL
CONDITIONS
MIN
4.325
4.250
4.10
2.5
TYP
4.350
4.275
4.15
2.6
MAX
4.375
4.300
4.20
2.7
UNITS
Overvoltage Detect
VOV
(Notes 1, 2)
V
Charge Enable
VCE
VUV
IOC
(Note 1)
(Note 1)
(Note 3)
(Note 1, 4)
(Note 3)
(Note 1)
V
V
Undervoltage Detect
Overcurrent Detect
Overcurrent Detect
Short-Circuit Detect
Short-Circuit Detect
Overvoltage Delay
Undervoltage Delay
Overcurrent Delay
Short-Circuit Delay
Test Threshold
1.8
1.9
2.0
A
VOC
ISC
45
47.5
8.0
50
mV
A
5.0
11
VSC
tOVD
tUVD
tOCD
tSCD
VTP
ITST
IRC
150
0.8
200
1
250
1.2
mV
s
90
100
10
110
20
ms
ms
ꢀs
V
5
160
0.5
200
1.0
240
1.5
Test Current
10
20
40
ꢀA
mA
Recovery Charge Current
(Note 5)
0.5
1
2
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DS2762 High-Precision Li+ Battery Monitor With Alerts
ELECTRICAL CHARACTERISTICS: TEMPERATURE, VOLTAGE, CURRENT
(2.5V ? VDD ? 5.5V, TA = -20°C to +50°C.)
PARAMETER
Temperature Resolution
Temperature Full-Scale Magnitude
Temperature Error
SYMBOL
TLSB
CONDITIONS
MIN
TYP
MAX
UNITS
LC
0.125
TFS
127
LC
TERR
(Note 6)
(Note 7)
M3
LC
Voltage Resolution
VLSB
4.88
mV
V
Voltage Full-Scale Magnitude
Voltage Offset Error
VFS
4.75
1.9
VOERR
VGERR
1
5
LSB
%
Voltage Gain Error
(Note 3)
(Note 4)
0.625
15.625
2.56
mA
ꢀV
Current Resolution
ILSB
(Notes 3, 4)
(Note 8)
A
Current Full-Scale Magnitude
Current Offset Error
IFS
64
mV
LSB
IOERR
IGERR
(Note 9)
1
3
1
(Notes 3, 10)
(Note 4)
Current Gain Error
%
(Note 3)
0.25
6.25
1456
M1
mAhr
µVhr
Hz
Accumulated Current Resolution
Current Sampling Frequency
Internal Timebase Accuracy
qCA
(Note 4)
fSAMP
tERR1
tERR2
(Note 11)
(Note 11)
%
M3
%
M6.5
EEPROM RELIABILITY SPECIFICATION
(2.5V ? VDD ? 5.5V, TA = -20LC to +70LC.)
PARAMETER
SYMBOL
tEEC
CONDITIONS
MIN
TYP
MAX
UNITS
ms
Copy to EEPROM Time
EEPROM Copy Endurance
2
10
NEEC
(Note 12)
25,000
cycles
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DS2762 High-Precision Li+ Battery Monitor With Alerts
ELECTRICAL CHARACTERISTICS: 1-WIRE INTERFACE
(2.5V ? VDD ? 5.5V, TA = -20LC to +70LC.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Time Slot
tSLOT
60
120
ꢀs
Recovery Time
tREC
tLOW0
tLOW1
tRDV
1
60
1
ꢀs
ꢀs
ꢀs
ꢀs
ꢀs
ꢀs
ꢀs
ꢀs
ꢀs
Write 0 Low Time
Write 1 Low Time
Read Data Valid
Reset Time High
Reset Time Low
Presence Detect High
Presence Detect Low
SWAP Timing Pulse Width
120
15
15
tRSTH
tRSTL
tPDH
480
480
15
960
60
tPDL
60
240
120
tSWL
0.2
SWAP Timing Pulse Falling Edge to DC
tSWOFF
(Note 13)
(Note 13)
0
0
1
ꢀs
Release
SWAP Timing Pulse Rising Edge to DC
tSWON
CDQ
1
ꢀs
Engage
DQ Capacitance
60
pF
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
All voltages are referenced to VSS.
See the Selector Guide section to determine the corresponding part number for each VOV value.
Internal current-sense resistor configuration.
External current-sense resistor configuration.
Test conditions are PLS = 4.1V, VDD = 2.5V. Maximum current for conditions of PLS = 15V, VDD = 0V is 10mA.
Self-heating due to output pin loading and sense resistor power dissipation can alter the reading from ambient conditions.
Voltage offset measurement is with respect to VOV at +25°C.
The current register supports measurement magnitudes up to 2.56A using the internal sense resistor option and 64mV with the
external resistor option. Compensation of the internal sense resistor value for process and temperature variation can reduce the
maximum reportable magnitude to 1.9A.
Note 7:
Note 8:
Note 9:
Current offset error null to ±1LSB typically requires 3.5s in-system calibration by user.
Note 10:
Current gain error specification applies to gain error in converting the voltage difference at IS1 and IS2, and excludes any error
remaining after the DS2762 compensates for the internal sense resistor’s temperature coefficient of 3700ppm/LC to an accuracy
of M500ppm/LC. The DS2762 does not compensate for external sense resistor characteristics, and any error terms arising from
the use of an external sense resistor should be taken into account when calculating total current measurement error.
Note 11:
Typical value for tERR1 is specified at 3.6V and +25LC, max value is specified for 0°C to +50°C. Max value for tERR2 is specified
for -20°C to +70°C.
Note 12:
Note 13:
Four-year data retention at +70LC.
Typical load capacitance on DC and CC is 1000pF.
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DS2762 High-Precision Li+ Battery Monitor With Alerts
PIN DESCRIPTION
PIN
SYMBOL
FUNCTION
FLIP
CHIP
TSSOP
Charge Protection Control Output. Controls an external P-channel high-side charge
1
C1
B1
CC
protection FET.
Battery Pack Positive Terminal Input. The DS2762 monitors the pack plus terminal
through PLS to detect overcurrent and overload conditions, as well as the presence of a
charge source. Additionally, a charge path to recover a deeply depleted cell is provided
from PLS to VDD. In sleep mode (with SWEN = 0), any capacitance or voltage source
connected to PLS is discharged internally to VSS through 200µA (nominal) to assure
reliable detection of a valid charge source. For details of other internal connections to
PLS and associated conditions see the Li+ Protection Circuitry section.
2
PLS
Discharge Protection Control Output. Controls an external P-channel high-side
3
B2
A3
DC
discharge protection FET.
Sense Resistor Connection. Connect to the negative terminal of the battery pack. In
the internal sense resistor configuration, the sense resistor is connected between VSS
and SNS.
4, 5, 6
SNS
Data Input/Out. 1-Wire data line. Open-drain output driver. Connect this pin to the DATA
terminal of the battery pack. Pin has an internal 1ꢀA pulldown for sensing disconnection.
7
B4
C4
D4
E4
F3
DQ
IS2
IS1
PS
8
Current-Sense Input. This pin is internally connected to SNS through a 4.7kꢁ resistor.
Current-Sense Input. This pin is internally connected to VSS through a 4.7kꢁ resistor.
Connect a 0.1ꢀF capacitor between IS1 and IS2 to complete a lowpass input filter.
9
10
Power Switch Sense Input. The device wakes up from sleep mode when it senses the
closure of a switch to VSS on this pin. Pin has an internal 1ꢀA pullup to VDD
.
Device Ground. Connect directly to the negative terminal of the Li+ cell. For the external
11, 12, 13
VSS
sense resistor configuration, connect the sense resistor between VSS and SNS.
Programmable I/O Pin. Can be configured to be used to control and monitor user-
14
E2
PIO
defined external circuitry or as an interrupt output to alert the host when preset current
accumulator or temperature limits are exceeded. Open drain to VSS
.
Power-Supply Input. Connect to the positive terminal of the Li+ cell through a
15
16
—
—
E1
D1
C2
D2
VDD
VIN
decoupling network.
Voltage Sense Input. The voltage of the Li+ cell is monitored through this input pin. This
pin has a weak pullup to VDD
.
SNS
Do not connect.
Probe
VSS
Do not connect.
Probe
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DS2762 High-Precision Li+ Battery Monitor With Alerts
Figure 1. Block Diagram
1-Wire
REGISTERS AND
DQ
INTERFACE
AND
DS2762
LOCKABLE EEPROM
SRAM
ADDRESS
VOLTAGE
THERMAL
SENSE
REFERENCE
ADC
TEMPERATURE
VOLTAGE
V
MUX
CURRENT
+
TIMEBASE
IS1
ACCUM. CURRENT
-
STATUS/CONTROL
PIO
IS2
PLS
PS
Li+ PROTECTION
CC
DC
INTERNAL SENSE RESISTOR
CONFIGURATION ONLY
25mꢀ
CHIP GROUND
SNS
V
IS2
IS1
DETAILED DESCRIPTION
The DS2762 high-precision Li+ battery monitor is a data-acquisition, information-storage, and safety-protection
device tailored for cost-sensitive battery pack applications. This low-power device integrates precise temperature,
voltage, and current measurement, nonvolatile (NV) data storage, and Li+ protection into the small footprint of
either a TSSOP package or flip-chip package. The DS2762 is a key component in applications including remaining
capacity estimation, safety monitoring, and battery-specific data storage.
Through its 1-Wire interface, the DS2762 gives the host system read/write access to status and control registers,
instrumentation registers, and general-purpose data storage. Each device has a unique factory-programmed 64-bit
net address that allows it to be individually addressed by the host system, supporting multibattery operation.
The DS2762 is capable of performing temperature, voltage, and current measurement to a resolution sufficient to
support process monitoring applications such as battery charge control, remaining capacity estimation, and safety
monitoring. Temperature is measured using an on-chip sensor, eliminating the need for a separate thermistor.
Bidirectional current measurement and accumulation are accomplished using either an internal 25mꢀ sense
resistor or an external device. The DS2762 also features a programmable I/O pin that allows the host system to
sense and control other electronics in the pack, including switches, vibration motors, speakers, and LEDs. This pin
may also be used to alert the host when preset accumulated current or temperature limits are exceeded.
Three types of memory are provided on the DS2762 for battery information storage: EEPROM, lockable EEPROM,
and SRAM. EEPROM memory saves important battery data in true NV memory that is unaffected by severe battery
depletion, accidental shorts, or ESD events. Lockable EEPROM becomes ROM when locked to provide additional
security for unchanging battery data. SRAM provides inexpensive storage for temporary data.
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DS2762 High-Precision Li+ Battery Monitor With Alerts
Figure 2. Application Example
102 x 2
BAT+
PACK+
150ꢀ
1kꢀ
1kꢀ
1kꢀ
DS2762
VIN
VDD
PIO
VSS
VSS
VSS
PS
CC
PLS
DC
PIO
150ꢀ
SNS
SNS
SNS
DQ
104
150ꢀ
PS
DATA
4.7kꢀ
IS1
IS2
102
104
PACK-
BAT-
RSNS
(NOTE 1)
NOTE 1: RSNS IS PRESENT FOR EXTERNAL SENSE RESISTOR
CONFIGURATIONS ONLY.
RSNS-INT
NOTE 2: RSNS-INT IS PRESENT FOR INTERNAL SENSE RESISTOR
CONFIGURATIONS ONLY.
(NOTE 2)
SNS
VSS
RKS
IS1
RKS
IS2
VOLTAGE
SENSE
DS2762
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DS2762 High-Precision Li+ Battery Monitor With Alerts
POWER MODES
The DS2762 has two power modes: active and sleep. While in active mode, the DS2762 continually measures
current, voltage, and temperature to provide data to the host system and to support current accumulation and Li+
safety monitoring. In sleep mode, the DS2762 ceases these activities. The DS2762 enters sleep mode when any of
the following conditions occurs:
C
The PMOD bit in the Status Register has been set to 1 and the DQ line is low for longer than 2s (pack
disconnection).
C
C
The voltage on VIN drops below undervoltage threshold VUV for tUVD (cell depletion).
The pack is disabled through the issuance of a SWAP command (SWEN bit = 1).
The DS2762 returns to active mode when any of the following occurs:
C
The PMOD bit has been set to 1 and the SWEN bit is set to 0 and the DQ line is pulled high (pack
connection).
C
C
C
The PS pin is pulled low (power switch).
The voltage on PLS becomes greater than the voltage on VIN (charger connection) with the SWEN bit set to 0.
The pack is enabled through the issuance of a SWAP command (SWEN bit = 1).
The DS2762 defaults to active mode when power is first applied.
Li+ PROTECTION CIRCUITRY
During active mode, the DS2762 constantly monitors cell voltage and current to protect the battery from overcharge
(overvoltage), overdischarge (undervoltage), and excessive charge and discharge currents (overcurrent, short
circuit). Conditions and DS2762 responses are described in the following sections and summarized in Table 1 and
Figure 3.
Table 1. Li+ Protection Conditions and DS2762 Responses
ACTIVATION
CONDITION
RELEASE THRESHOLD
THRESHOLD
DELAY
RESPONSE
VIN < VCE, or
Overvoltage
VIN > VOV
tOVD
CC high
VIS ≤ -2mV
(1)
CC, DC high,
VPLS > VDD
Undervoltage
VIN < VUV
tUVD
tOCD
tOCD
tSCD
Sleep Mode
(charger connected)
(2)
(3)
Overcurrent, Charge
Overcurrent, Discharge
Short Circuit
VIS > VOC
VPLS < VDD - VTP
CC, DC high
(2)
(4)
(4)
VIS < -VOC
V
PLS > VDD - VTP
PLS > VDD - VTP
DC high
VSNS > VSC
V
DC high
VIS = VIS1 - VIS2. Logic high = VPLS for CC and VDD for DC. All voltages are with respect to VSS. ISNS references current delivered from pin SNS.
Note 1:
Note 2:
If VDD < 2.2V, release is delayed until the recovery charge current (IRC) passed from PLS to VDD charges the battery and allows VDD
to exceed 2.2V.
For the internal sense resistor configuration, the overcurrent thresholds are expressed in terms of current: I
> I for charge
SNS
OC
direction and I
< -I for discharge direction.
SNS
OC
Note 3:
Note 4:
With test current I
With test current I
flowing from PLS to VSS (pulldown on PLS).
flowing from VDD to PLS (pullup on PLS).
TST
TST
Overvoltage. If the cell voltage on VIN exceeds the overvoltage threshold, VOV, for a period longer than overvoltage
delay, tOVD, the DS2762 shuts off the external charge FET and sets the OV flag in the protection register. When the
cell voltage falls below charge enable threshold VCE, the DS2762 turns the charge FET back on (unless another
protection condition prevents it). Discharging remains enabled during overvoltage, and the DS2762 re-enables the
charge FET before VIN < VCE if a discharge current of -80mA (VIS ≤ -2mV) or less is detected.
Undervoltage. If the voltage of the cell drops below undervoltage threshold, VUV, for a period longer than
undervoltage delay, tUVD, the DS2762 shuts off the charge and discharge FETs, sets the UV flag in the protection
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DS2762 High-Precision Li+ Battery Monitor With Alerts
register, and enters sleep mode. The DS2762 provides a current-limited (IRC) recovery charge path from PLS to
VDD to gently charge severely depleted cells. The recovery path is enabled when 0 ? VDD < 3V (typ). Once VDD
reaches 3V (typ), the DS2762 returns to normal operation, awaiting connection of a charger to turn on the charge
FET and pull out of sleep mode.
Overcurrent, Charge Direction. The voltage difference between the IS1 pin and the IS2 pin (VIS = VIS1 - VIS2) is the
filtered voltage drop across the current-sense resistor. If VIS exceeds overcurrent threshold VOC for a period longer
than overcurrent delay tOCD, the DS2762 shuts off both external FETs and sets the COC flag in the protection
register. The charge current path is not re-established until the voltage on the PLS pin drops below VDD - VTP. The
DS2762 provides a test current of value ITST from PLS to VSS to pull PLS down to detect the removal of the
offending charge current source.
Overcurrent, Discharge Direction. If VIS is less than -VOC for a period longer than tOCD, the DS2762 shuts off the
external discharge FET and sets the DOC flag in the protection register. The discharge current path is not re-
established until the voltage on PLS rises above VDD - VTP. The DS2762 provides a test current of value ITST from
VDD to PLS to pull PLS up to detect the removal of the offending low-impedance load.
Short Circuit. If the voltage on the SNS pin with respect to VSS exceeds short-circuit threshold VSC for a period
longer than short-circuit delay tSCD, the DS2762 shuts off the external discharge FET and sets the DOC flag in the
protection register. The discharge current path is not re-established until the voltage on PLS rises above VDD - VTP.
The DS2762 provides a test current of value ITST from VDD to PLS to pull PLS up to detect the removal of the short
circuit.
Figure 3. Li+ Protection Circuitry Example Waveforms
VOV
VCE
VCELL
VUV
CHARGE
VIS
VOC
0
-VOC
-VSC
DISCHARGE
(NOTE 1)
VPLS
VSS
tOVD
tOVD
tOCD
CC
DC
VDD
VSS
t
t
t
ACTIVE
SLEEP
MODE
INACTIVE
NOTE 1: TO ALLOW THE DEVICE TO REACT QUICKLY TO SHORT CIRCUITS, DETECTION OCCURS ON THE SNS PIN RATHER THAN ON THE
Summary. All of the protection conditions described above are ORed together to affect the CC and DC outputs.
DC = (Undervoltage) or (Overcurrent, Either Direction) or (Short Circuit) or (Protection Register Bit DE = 0)
or (Sleep Mode)
CC = (Overvoltage) or (Undervoltage) or (Overcurrent, Charge Direction) or (Protection Register bit CE = 0)
or (Sleep Mode)
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DS2762 High-Precision Li+ Battery Monitor With Alerts
CURRENT MEASUREMENT
In active mode, the DS2762 continually measures the current flow into and out of the battery by measuring the
voltage drop across a current-sense resistor. The DS2762 is available in two configurations: 1) internal 25mꢀ
current-sense resistor and 2) external user-selectable sense resistor. In either configuration, the DS2762 considers
the voltage difference between pins IS1 and IS2 (VIS = VIS1 - VIS2) to be the filtered voltage drop across the sense
resistor. A positive VIS value indicates current is flowing into the battery (charging), while a negative VIS value
indicates current is flowing out of the battery (discharging).
VIS is measured with a signed resolution of 12 bits. The current register is updated in two’s-complement format
every 88ms with an average of 128 readings. Currents outside the register range are reported at the range limit.
Figure 4 shows the format of the current register.
For the internal sense resistor configuration, the DS2762 maintains the current register in units of amps, with a
resolution of 0.625mA and full-scale range of no less than M1.9A (see Note 7 on IFS spec for more details). The
DS2762 automatically compensates for internal sense resistor process variations and temperature effects when
reporting current.
For the external sense resistor configuration, the DS2762 writes the measured VIS voltage to the current register,
with a 15.625ꢁV resolution and a full-scale M64mV range.
Figure 4. Current Register Format
MSB—Address 0E
211 210 29 28 27
LSB—Address 0F
22 21 20
S
26
25
24
23
X
X
X
MSb
LSb
MSb
LSb
Units: 0.625mA for Internal Sense Resistor
15.625ꢀV for External Sense Resistor
CURRENT ACCUMULATOR
The current accumulator facilitates remaining capacity estimation by tracking the net current flow into and out of the
battery. Current flow into the battery increments the current accumulator while current flow out of the battery
decrements it. Data is maintained in the current accumulator in two’s-complement format. Figure 5 shows the
format of the current accumulator.
When the internal sense resistor is used, the DS2762 maintains the current accumulator in units of amp-hours, with
a 0.25mAhrs resolution and full-scale M8.2Ahrs range. When using an external sense resistor, the DS2762
maintains the current accumulator in units of volt-hours, with a 6.25ꢁVhrs resolution and a full-scale M205mVhrs
range.
The current accumulator is a read/write register that can be altered by the host system as needed.
Figure 5. Current Accumulator Format
MSB—Address 10
LSB—Address 11
25 24 23 22
S
214 213 212 211 210 29
28
27
26
21 20
LSb
MSb
LSb
MSb
Units: 0.25mAhrs for Internal Sense Resistor
6.25ꢀVhrs for External Sense Resistor
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DS2762 High-Precision Li+ Battery Monitor With Alerts
CURRENT OFFSET COMPENSATION
Current measurement and current accumulation are internally compensated for offset on a continual basis
minimizing error resulting from variations in device temperature and voltage. Additionally, a constant bias can be
used to alter any other sources of offset. This bias resides in EEPROM address 33h in two’s-complement format
and is subtracted from each current measurement. The current offset bias is applied to the internal and external
sense resistor configurations. The factory default for the current offset bias is 0.
Figure 6. Current Offset Bias
Address 33
S
26
25
24
23
22
21 20
LSb
MSb
Units: 0.625mA for Internal Sense Resistor
15.625ꢀV for External Sense Resistor
VOLTAGE MEASUREMENT
The DS2762 continually measures the voltage between pins VIN and VSS over a 0 to 4.75V range. The voltage
register is updated in two’s-complement format every 3.4ms with a 4.88mV resolution. Voltages above the
maximum register value are reported as the maximum value. Figure 7 shows the voltage register format.
Figure 7. Voltage Register Format
MSB—Address 0C
28 27 26 25
LSB—Address 0D
20
S
29
24
23
22
21
X
X
X
X
X
MSb
LSb
MSb
LSb
Units: 4.88mV
TEMPERATURE MEASUREMENT
The DS2762 uses an integrated temperature sensor to continually measure battery temperature. Temperature
measurements are placed in the temperature register every 220ms in two’s-complement format with a 0.125°C
resolution over a M127°C range. Figure 8 shows the temperature register format.
Figure 8. Temperature Register Format
MSB—Address 18
28 27 26 25
LSB—Address 19
20
S
29
24
23
22
21
X
X
X
X
X
MSb
LSb
MSb
LSb
Units: 0.125LC
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DS2762 High-Precision Li+ Battery Monitor With Alerts
PROGRAMMABLE I/O
To use the PIO pin as described in this section, the IE bit (bit 2) of the Status Register must be set to 0.
To use the PIO pin as an output, write the desired output value to the PIO bit in the special feature register. Writing
a 0 to the PIO bit enables the PIO output driver, pulling the PIO pin to VSS. Writing a 1 to the PIO bit disables the
output driver, allowing the PIO pin to be pulled high or used as an input. To sense the value on the PIO pin, read
the PIO bit. The DS2762 turns off the PIO output driver and sets the PIO bit high when in sleep mode or when DQ
is low for more than 2s, regardless of the state of the PMOD bit.
ALARM COMPARATORS
The PIO pin can be programmed as an interrupt output (active low) to alert the host system of critical events. To
use the Interrupt feature, the Interrupt Enable (IE) bit (bit 2) of the Status Register must be set to a 1. Interrupt
threshold values can be programmed by the user in the designated SRAM memory registers in the formats and
locations found in Figure 9. Since these thresholds are located in SRAM memory, they must be reprogrammed if a
loss of power to the DS2762 occurs. The PIO line will go low to interrupt the system host and indicate that one of
the following events has occurred:
S
S
S
S
Accumulated Current O Current Accumulator Interrupt High Threshold
Accumulated Current ? Current Accumulator Interrupt Low Threshold
Temperature O Temperature Interrupt High Threshold
Temperature ? Temperature Interrupt Low Threshold
The host may then poll the DS2762 to determine which threshold has been met or exceeded.
Figure 9. Interrupt Threshold Register Formats
Current Accumulator Interrupt High Threshold
MSB—Address 80
LSB—Address 81
25 24 23 22
S
214 213 212 211 210 29
28
27
26
21 20
LSb
MSb
LSb
MSb
Units: 0.25mAhrs for Internal Sense Resistor
6.25ꢀVhrs for External Sense Resistor
Current Accumulator Interrupt Low Threshold
MSB—Address 82
LSB—Address 83
S
214 213 212 211 210 29
28
27
26
25
24
23
22
21 20
LSb
MSb
LSb
MSb
Units: 0.25mAhrs for Internal Sense Resistor
6.25ꢀVhrs for External Sense Resistor
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DS2762 High-Precision Li+ Battery Monitor With Alerts
Temperature Interrupt High Threshold
Address 84
24 23
S
26
25
22
21 20
LSb
MSb
Units: 1.0°C
Temperature Alarm Low Threshold
Address 85
24 23
S
26
25
22
21 20
MSb
LSb
Units: 1.0°C
POWER SWITCH INPUT
The DS2762 provides a power control function that uses the discharge protection FET to gate battery power to the
system. The PS pin, internally pulled to VDD through a 1ꢁA current source, is continuously monitored for a low-
impedance connection to VSS. If the DS2762 is in sleep mode, the detection of a low on the PS pin causes the
device to transition into active mode, turning on the discharge FET. If the DS2762 is already in active mode, activity
on PS has no effect other than the latching of its logic low level in the PS bit in the special feature register. The
reading of a 0 in the PS bit should be immediately followed by writing a 1 to the PS bit to ensure that a subsequent
low forced on the PS pin is latched into the PS bit.
MEMORY
The DS2762 has a 256-byte linear address space with registers for instrumentation, status, and control in the lower
32 bytes, with lockable EEPROM and SRAM memory occupying portions of the remaining address space. All
EEPROM memory is general purpose except addresses 30h, 31h, and 33h, which should be written with the
default values for the protection register, status register, and current offset register, respectively. All SRAM memory
is general purpose. When the MSB of any two-byte register is read, both the MSB and LSB are latched and held for
the duration of the read data command to prevent updates during the read and ensure synchronization between
the two register bytes. For consistent results, always read the MSB and the LSB of a two-byte register during the
same read data command sequence.
EEPROM memory is shadowed by RAM to eliminate programming delays between writes and to allow the data to
be verified by the host system before being copied to EEPROM. All reads and writes to/from EEPROM memory
actually access the shadow RAM. In unlocked EEPROM blocks, the write data command updates shadow RAM. In
locked EEPROM blocks, the write data command is ignored. The copy data command copies the contents of
shadow RAM to EEPROM in an unlocked block of EEPROM but has no effect on locked blocks. The recall-data
command copies the contents of a block of EEPROM to shadow RAM regardless of whether the block is locked or
not.
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DS2762 High-Precision Li+ Battery Monitor With Alerts
Table 2. Memory Map
ADDRESS (HEX)
DESCRIPTION
READ/WRITE
00
Protection Register
R/W
01
Status Register
Reserved
R
02–06
07
EEPROM Register
Special Feature Register
Reserved
R/W
R/W
08
09–0B
0C
Voltage Register MSB
Voltage Register LSB
Current Register MSB
Current Register LSB
R
R
R
R
0D
0E
0F
10
Accumulated Current Register MSB
Accumulated Current Register LSB
Reserved
R/W
11
R/W
12–17
18
Temperature Register MSB
Temperature Register LSB
Reserved
R
R
19
1A–1F
20–2F
30–3F
40–7F
80
EEPROM, block 0
R/W*
R/W*
EEPROM, block 1
Reserved
SRAM (Optional Accumulated Current Interrupt
High Threshold MSB)
R/W
R/W
R/W
R/W
R/W
R/W
R/W
81
82
83
84
85
SRAM (Optional Accumulated Current Interrupt
High Threshold LSB)
SRAM (Optional Accumulated Current Interrupt
Low Threshold MSB)
SRAM (Optional Accumulated Current Interrupt
Low Threshold LSB)
SRAM (Optional Temperature Interrupt High
Threshold)
SRAM (Optional Temperature Interrupt Low
Threshold)
86-8F
SRAM
90–FF
Reserved
* Each EEPROM block is read/write until locked by the LOCK command, after which it is read-only.
PROTECTION REGISTER
The protection register consists of flags that indicate protection circuit status and switches that give conditional
control over the charging and discharging paths. Bits OV, UV, COC, and DOC are set when corresponding
protection conditions occur and remain set until cleared by the host system. The default values of the CE and DE
bits of the protection register are stored in lockable EEPROM in the corresponding bits in address 30h. A recall
data command for EEPROM block 1 recalls the default values into CE and DE. Figure 10 shows the format of the
protection register. The function of each bit is described in detail in the following paragraphs.
Figure 10. Protection Register Format
ADDRESS 00
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
OV
UV
COC
DOC
CC
DC
CE
DE
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DS2762 High-Precision Li+ Battery Monitor With Alerts
OV—Overvoltage Flag. When set to 1, this bit indicates the battery pack has experienced an overvoltage condition.
This bit must be reset by the host system.
UV—Undervoltage Flag. When set to 1, this bit indicates the battery pack has experienced an undervoltage
condition. This bit must be reset by the host system.
COC—Charge Overcurrent Flag. When set to 1, this bit indicates the battery pack has experienced a charge-
direction overcurrent condition. This bit must be reset by the host system.
DOC—Discharge Overcurrent Flag. When set to 1, this bit indicates the battery pack has experienced a discharge-
direction overcurrent condition. This bit must be reset by the host system.
CC—CC Pin Mirror. This read-only bit mirrors the state of the CC output pin.
DC—DC Pin Mirror. This read-only bit mirrors the state of the DC output pin.
CE—Charge Enable. Writing a 0 to this bit disables charging (CC output high, external charge FET off) regardless
of cell or pack conditions. Writing a 1 to this bit enables charging, subject to override by the presence of any
protection conditions. The DS2762 automatically sets this bit to 1 when it transitions from sleep mode to active
mode.
DE—Discharge Enable. Writing a 0 to this bit disables discharging (DC output high, external discharge FET off)
regardless of cell or pack conditions. Writing a 1 to this bit enables discharging, subject to override by the presence
of any protection conditions. The DS2762 automatically sets this bit to 1 when it transitions from sleep mode to
active mode.
STATUS REGISTER
The default values for the status register bits are stored in lockable EEPROM in the corresponding bits of address
31h. A recall data command for EEPROM block 1 recalls the default values into the status register bits. The format
of the status register is shown in Figure 11. The function of each bit is described in detail in the following
paragraphs.
Figure 11. Status Register Format
ADDRESS 01
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
X
X
PMOD
RNAOP
SWEN
IE
X
X
X—Reserved Bits.
PMOD—Sleep Mode Enable. A value of 1 in this bit enables the DS2762 to enter sleep mode when the DQ line
goes low for greater than 2s and to leave sleep mode when the DQ line goes high. A value of 0 disables DQ-
related transitions into and out of sleep mode. This bit is read-only. The desired default value should be set in bit 5
of address 31h. The factory default is 0.
RNAOP—Read Net Address Opcode. A value of 0 in this bit sets the opcode for the read net address command to
33h, while a 1 sets the opcode to 39h. This bit is read-only. The desired default value should be set in bit 4 of
address 31h. The factory default is 0.
SWEN—SWAP Command Enable. A value of 1 in this bit location enables the recognition of a SWAP command. If
set to 0, SWAP commands are ignored. The desired default value should be set in bit 3 of address 31h. This bit is
read-only. The factory default is 0.
IE—Interrupt Enable. A value of 1 in this bit location enables the PIO pin to be used as an interrupt to the host
system when either the user-programmed thresholds for Accumulated Current and Temperature are met or
exceeded. If set to 0, the PIO pin performs as noted in the PIO section. This bit is read-only. The desired default
value should be set in bit 2 of address 31h. The factory default is 0.
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DS2762 High-Precision Li+ Battery Monitor With Alerts
EEPROM REGISTER
The format of the EEPROM register is shown in Figure 12. The function of each bit is described in detail in the
following paragraphs.
Figure 12. EEPROM Register Format
ADDRESS 07
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
EEC
LOCK
X
X
X
X
BL1
BL0
EEC—EEPROM Copy Flag. A 1 in this read-only bit indicates that a copy data command is in progress. While this
bit is high, writes to EEPROM addresses are ignored. A 0 in this bit indicates that data may be written to unlocked
EEPROM blocks.
LOCK—EEPROM Lock Enable. When this bit is 0, the lock command is ignored. Writing a 1 to this bit enables the
lock command. After the lock command is executed, the LOCK bit is reset to 0. The factory default is 0.
BL1—EEPROM Block 1 Lock Flag. A 1 in this read-only bit indicates that EEPROM block 1 (addresses 30 to 3F) is
locked (read-only) while a 0 indicates block 1 is unlocked (read/write).
BL0—EEPROM Block 0 Lock Flag. A 1 in this read-only bit indicates that EEPROM block 0 (addresses 20 to 2F) is
locked (read-only) while a 0 indicates block 0 is unlocked (read/write).
X—Reserved Bits.
SPECIAL FEATURE REGISTER
The format of the special feature register is shown in Figure 13. The function of each bit is described in detail in the
following paragraphs.
Figure 13. Special Feature Register Format
ADDRESS 08
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
PIO
MSTR
X
X
X
X
X
PS
PS—PS Pin Latch. This bit latches a low state on the PS pin, and is cleared only by writing a 1 to this location.
Writing this bit to a 1 immediately upon reading of a 0 value is recommended.
PIO—PIO Pin Sense and Control. See the Programmable I/O section for details on this read/write bit.
MSTR—SWAP Master Status Bit. This bit indicates whether a device has been selected through the SWAP
command. Selection of this device through the SWAP command and the appropriate net address results in setting
this bit, indicating that this device is the master. A 0 signifies that this device is not the master.
X—Reserved Bits.
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DS2762 High-Precision Li+ Battery Monitor With Alerts
1-Wire BUS SYSTEM
The 1-Wire bus is a system that has a single bus master and one or more slaves. A multidrop bus is a 1-Wire bus
with multiple slaves. A single-drop bus has only one slave device. In all instances, the DS2762 is a slave device.
The bus master is typically a microprocessor in the host system. The discussion of this bus system consists of four
topics: 64-bit net address, hardware configuration, transaction sequence, and 1-Wire signaling.
64-BIT NET ADDRESS
Each DS2762 has a unique, factory-programmed 1-Wire net address that is 64 bits in length. The first eight bits are
the 1-Wire family code (30h for DS2762). The next 48 bits are a unique serial number. The last eight bits are a
cyclic redundancy check (CRC) of the first 56 bits (see Figure 14). The 64-bit net address and the 1-Wire I/O
circuitry built into the device enable the DS2762 to communicate through the 1-Wire protocol detailed in the 1-Wire
Bus System section of this data sheet.
Figure 14. 1-Wire Net Address Format
8-BIT FAMILY
8-BIT CRC
MSb
48-BIT SERIAL NUMBER
CODE (30H)
LSb
CRC GENERATION
The DS2762 has an 8-bit CRC stored in the most significant byte of its 1-Wire net address. To ensure error-free
transmission of the address, the host system can compute a CRC value from the first 56 bits of the address and
compare it to the CRC from the DS2762. The host system is responsible for verifying the CRC value and taking
action as a result. The DS2762 does not compare CRC values and does not prevent a command sequence from
proceeding as a result of a CRC mismatch. Proper use of the CRC can result in a communication channel with a
very high level of integrity.
The CRC can be generated by the host using a circuit consisting of a shift register and XOR gates as shown in
Figure 15, or it can be generated in software. Additional information about the Dallas 1-Wire CRC is available in
Application Note 27: Understanding and Using Cyclic Redundancy Checks with Dallas Semiconductor Touch
Memory Products (www.maxim-ic.com/appnoteindex).
In the circuit in Figure 15, the shift register bits are initialized to 0. Then, starting with the least significant bit of the
family code, one bit at a time is shifted in. After the 8th bit of the family code has been entered, then the serial
number is entered. After the 48th bit of the serial number has been entered, the shift register contains the CRC
value.
Figure 15. 1-Wire CRC Generation Block Diagram
INPUT
MSb
LSb
XOR
XOR
XOR
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DS2762 High-Precision Li+ Battery Monitor With Alerts
HARDWARE CONFIGURATION
Because the 1-Wire bus has only a single line, it is important that each device on the bus be able to drive it at the
appropriate time. To facilitate this, each device attached to the 1-Wire bus must connect to the bus with open-drain
or tri-state output drivers. The DS2762 used an open-drain output driver as part of the bidirectional interface
circuitry shown in Figure 16. If a bidirectional pin is not available on the bus master, separate output and input pins
can be connected together.
The 1-Wire bus must have a pullup resistor at the bus-master end of the bus. For short line lengths, the value of
this resistor should be approximately 5kꢀ. The idle state for the 1-Wire bus is high. If, for any reason, a bus
transaction must be suspended, the bus must be left in the idle state to properly resume the transaction later. If the
bus is left low for more than 120ꢁs, slave devices on the bus begin to interpret the low period as a reset pulse,
effectively terminating the transaction.
Figure 16. 1-Wire Bus Interface Circuitry
VPULLUP
BUS MASTER
DS2762 1-Wire PORT
(2.0V to 5.5V)
4.7kꢀ
Rx
Rx
Tx
1ꢁA
Tx
(typ)
Rx = RECEIVE
Tx = TRANSMIT
100ꢀ
MOSFET
TRANSACTION SEQUENCE
The protocol for accessing the DS2762 through the 1-Wire port is as follows:
C
C
C
C
Initialization
Net Address Command
Function Command
Transaction/Data
The sections that follow describe each of these steps in detail.
All transactions of the 1-Wire bus begin with an initialization sequence consisting of a reset pulse transmitted by the
bus master, followed by a presence pulse simultaneously transmitted by the DS2762 and any other slaves on the
bus. The presence pulse tells the bus master that one or more devices are on the bus and ready to operate. For
more details, see the 1-Wire Signaling section.
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DS2762 High-Precision Li+ Battery Monitor With Alerts
NET ADDRESS COMMANDS
Once the bus master has detected the presence of one or more slaves, it can issue one of the net address
commands described in the following paragraphs. The name of each ROM command is followed by the 8-bit
opcode for that command in square brackets. Figure 17 presents a transaction flowchart of the net address
commands.
Read Net Address [33h or 39h]. This command allows the bus master to read the DS2762’s 1-Wire net address.
This command can only be used if there is a single slave on the bus. If more than one slave is present, a data
collision occurs when all slaves try to transmit at the same time (open drain produces a wired-AND result). The
RNAOP bit in the status register selects the opcode for this command, with RNAOP = 0 indicating 33h, and
RNAOP = 1 indicating 39h.
Match Net Address [55h]. This command allows the bus master to specifically address one DS2762 on the 1-Wire
bus. Only the addressed DS2762 responds to any subsequent function command. All other slave devices ignore
the function command and wait for a reset pulse. This command can be used with one or more slave devices on
the bus.
Skip Net Address [CCh]. This command saves time when there is only one DS2762 on the bus by allowing the
bus master to issue a function command without specifying the address of the slave. If more than one slave device
is present on the bus, a subsequent function command can cause a data collision when all slaves transmit data at
the same time.
Search Net Address [F0h]. This command allows the bus master to use a process of elimination to identify the
1-Wire net addresses of all slave devices on the bus. The search process involves the repetition of a simple three-
step routine: read a bit, read the complement of the bit, then write the desired value of that bit. The bus master
performs this simple three-step routine on each bit location of the net address. After one complete pass through all
64 bits, the bus master knows the address of one device. The remaining devices can then be identified on
additional iterations of the process. See Chapter 5 of the Book of DS19xx iButton® Standards for a comprehensive
discussion of a net address search, including an actual example (www.maxim-ic.com/iButtonBook).
SWAP [AAh]. SWAP is a ROM level command specifically intended to aid in distributed multiplexing applications
and is described specifically with regards to power control using the 27xx series of products. The term power
control refers to the ability of the DS2762 to control the flow of power into or out the battery pack using control pins
DC and CC. The SWAP command is issued followed by the net address. The effect is to cause the addressed
device to enable power to or from the system while simultaneously (break-before-make) deselecting and powering
down (SLEEP) all other packs. This switching sequence is controlled by a timing pulse issued on the DQ line
following the net address. The falling edge of the pulse is used to disable power with the rising edge enabling
power flow by the selected device. The DS2762 recognizes a SWAP command, device address, and timing pulse
only if the SWEN bit is set.
FUNCTION COMMANDS
After successfully completing one of the net address commands, the bus master can access the features of the
DS2762 with any of the function commands described in the following paragraphs and summarized in Table 3. The
name of each function is followed by the 8-bit opcode for that command in square brackets.
Read Data [69h, XX]. This command reads data from the DS2762 starting at memory address XX. The LSb of the
data in address XX is available to be read immediately after the MSb of the address has been entered. Because
the address is automatically incremented after the MSb of each byte is received, the LSb of the data at address XX
+ 1 is available to be read immediately after the MSb of the data at address XX. If the bus master continues to read
beyond address FFh, the DS2762 outputs logic 1 until a reset pulse occurs. Addresses labeled “Reserved” in the
memory map contain undefined data. The read data command can be terminated by the bus master with a reset
pulse at any bit boundary.
iButton is a registered trademark of Dallas Semiconductor.
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DS2762 High-Precision Li+ Battery Monitor With Alerts
Write Data [6Ch, XX]. This command writes data to the DS2762 starting at memory address XX. The LSb of the
data to be stored at address XX can be written immediately after the MSb of address has been entered. Because
the address is automatically incremented after the MSb of each byte is written, the LSb to be stored at address XX
+ 1 can be written immediately after the MSb to be stored at address XX. If the bus master continues to write
beyond address FFh, the DS2762 ignores the data. Writes to read-only addresses, reserved addresses and locked
EEPROM blocks are ignored. Incomplete bytes are not written. Writes to unlocked EEPROM blocks are to shadow
RAM rather than EEPROM. See the Memory section for more details.
Copy Data [48h, XX]. This command copies the contents of shadow RAM to EEPROM for the 16-byte EEPROM
block containing address XX. Copy data commands that address locked blocks are ignored. While the copy data
command is executing, the EEC bit in the EEPROM register is set to 1 and writes to EEPROM addresses are
ignored. Reads and writes to non-EEPROM addresses can still occur while the copy is in progress. The copy data
command execution time, tEEC, is 2ms typical and starts after the last address bit is transmitted.
Recall Data [B8h, XX]. This command recalls the contents of the 16-byte EEPROM block containing address XX
to shadow RAM.
Lock [6Ah, XX]. This command locks (write-protects) the 16-byte block of EEPROM memory containing memory
address XX. The LOCK bit in the EEPROM register must be set to l before the lock command is executed. If the
LOCK bit is 0, the lock command has no effect. The lock command is permanent; a locked block can never be
written again.
Table 3. Function Commands
COMMAND
PROTOCOL
BUS STATE AFTER
COMMAND
FUNCTION
BUS DATA
COMMAND PROTOCOL
Reads data from memory
starting at address XX
Up to 256 bytes of
data
Read Data
69h, XX
6Ch, XX
48h, XX
B8h, XX
6Ah, XX
Master Rx
Master Tx
Bus idle
Writes data to memory
starting at address XX
Up to 256 bytes of
data
Write Data
Copy Data
Recall Data
Lock
Copies shadow RAM data to
EEPROM block containing
address XX
None
None
None
Recalls EEPROM block
containing address XX to
shadow RAM
Bus idle
Permanently locks the block
of EEPROM
Bus idle
containing address XX
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DS2762 High-Precision Li+ Battery Monitor With Alerts
Figure 17. Net Address Command Flow Chart
MASTER Tx
RESET PULSE
DS2762 Tx
PRESENCE PULSE
MASTER Tx
NET ADDRESS
COMMAND
33h / 39h
READ
NO
55h
NO
F0h
NO
AAh
NO
CCh
NO
MATCH
SEARCH
SWAP
SKIP
YES
YES
YES
YES
YES
MASTER Tx
BIT 0
MASTER TX
MASTER TX
FUNCTION
COMMAND
DS2762 Tx
FAMILY CODE
1 BYTE
DS2762 Tx BIT 0
DS2762 Tx BIT 0
MASTER Tx BIT 0
BIT 0
DS2762 Tx
SERIAL NUMBER
6 BYTES
BIT 0
NO
NO
BIT 0
NO
BIT 0
MATCH ?
MATCH ?
MATCH ?
DS2762 Tx
CRC
1 BYTE
YES
YES
YES
MASTER TX
MASTER TX
DS2762 Tx BIT 1
DS2762 Tx BIT 1
MASTER Tx BIT 1
BIT 1
BIT 1
BIT 1
NO
NO
BIT 1
NO
BIT 1
MATCH ?
MATCH ?
MATCH ?
YES
YES
YES
MASTER TX
MASTER TX
DS2762 Tx BIT 63
DS2762 Tx BIT 63
MASTER Tx BIT 63
BIT 63
BIT 63
MASTER TX
FUNCTION
COMMAND
NO
YES
BIT 63
BIT 63
YES
MATCH ?
MATCH ?
NO
FALLING EDGE
OF DQ
RISING EDGE
OF DQ
DS2762 TO
DS2762 TO
SLEEP MODE
ACTIVE MODE
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DS2762 High-Precision Li+ Battery Monitor With Alerts
I/O SIGNALING
The 1-Wire bus requires strict signaling protocols to ensure data integrity. The four protocols used by the DS2762
are as follows: the initialization sequence (reset pulse followed by presence pulse), write 0, write 1, and read data.
The bus master initiates all these types of signaling except the presence pulse.
The initialization sequence required to begin any communication with the DS2762 is shown in Figure 18. A
presence pulse following a reset pulse indicates that the DS2762 is ready to accept a net address command. The
bus master transmits (Tx) a reset pulse for tRSTL. The bus master then releases the line and goes into receive mode
(Rx). The 1-Wire bus line is then pulled high by the pullup resistor. After detecting the rising edge on the DQ pin,
the DS2762 waits for tPDH and then transmits the presence pulse for tPDL
.
Figure 18. 1-Wire Initialization Sequence
tRSTL
tRSTH
tPDH
tPDL
PACK+
PACK-
DQ
LINE TYPE LEGEND:
BOTH BUS MASTER AND
DS2762 ACTIVE LOW
WRITE-TIME SLOTS
A write-time slot is initiated when the bus master pulls the 1-Wire bus from a logic-high (inactive) level to a logic-low
level. There are two types of write-time slots: write 1 and write 0. All write-time slots must be tSLOT (60ꢁs to 120ꢁs)
in duration with a 1ꢁs minimum recovery time, tREC, between cycles. The DS2762 samples the 1-Wire bus line
between 15ꢁs and 60ꢁs after the line falls. If the line is high when sampled, a write 1 occurs. If the line is low when
sampled, a write 0 occurs (Figure 19). For the bus master to generate a write 1 time slot, the bus line must be
pulled low and then released, allowing the line to be pulled high within 15ꢁs after the start of the write time slot. For
the host to generate a write 0 time slot, the bus line must be pulled low and held low for the duration of the write-
time slot.
READ-TIME SLOTS
A read-time slot is initiated when the bus master pulls the 1-Wire bus line from a logic-high level to a logic-low level.
The bus master must keep the bus line low for at least 1ꢁs and then release it to allow the DS2762 to present valid
data. The bus master can then sample the data tRDV (15ꢁs) from the start of the read-time slot. By the end of the
read-time slot, the DS2762 releases the bus line and allows it to be pulled high by the external pullup resistor. All
read-time slots must be tSLOT (60ꢁs to 120ꢁs) in duration with a 1ꢁs minimum recovery time, tREC, between cycles.
See Figure 19 for more information.
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DS2762 High-Precision Li+ Battery Monitor With Alerts
Figure 19. 1-Wire Write- and Read-Time Slots
WRITE 0 SLOT
WRITE 1 SLOT
tSLOT
tSLOT
t
t
t
PACK+
DQ
PACK-
DS2762 SAMPLE WINDOW
DS2762 SAMPLE WINDOW
>1ꢀs
15ꢀs
15ꢀs
30ꢀs
15ꢀs
15ꢀs
30ꢀs
READ 0 SLOT
READ 1 SLOT
tSLOT
tSLOT
t
PACK+
PACK–
DQ
>1ꢀs
MASTER SAMPLE WINDOW
LINE TYPE LEGEND:
tRDV
tRDV
BOTH BUS MASTER AND
DS2762 ACTIVE LOW
Figure 20. Swap Command Timing
tSWL
DQ
tSWOFF
CC, DC
tSWON
CC, DC
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DS2762 High-Precision Li+ Battery Monitor With Alerts
SELECTOR GUIDE
PART
MARKING
PACKAGE INFORMATION
DS2762AE
DS2762A
DS2762B
DS2762A
DS2762B
2762A25
2762B25
2762A25
2762B25
DS2762AR
DS2762BR
DS2762A
DS2762B
TSSOP, External Sense Resistor, 4.275V VOV
DS2762BE
TSSOP, External Sense Resistor, 4.35V VOV
DS2762AE on Tape-and-Reel
DS2762AE/T&R
DS2762BE/T&R
DS2762AE-025
DS2762BE-025
DS2762AE-025/T&R
DS2762BE-025/T&R
DS2762AX-025/T&R
DS2762BX-025/T&R
DS2762AX/T&R
DS2762BE on Tape-and-Reel
TSSOP, 25mꢀ Sense Resistor, 4.275V VOV
TSSOP, 25mꢀ Sense Resistor, 4.35V VOV
DS2762AE-025 in Tape-and-Reel
DS2762BE-025 in Tape-and-Reel
Flip-Chip, 25mꢀ Sense Resistor, Tape-and-Reel, 4.275V VOV
Flip-Chip, 25mꢀ Sense Resistor, Tape-and-Reel, 4.35V VOV
Flip-Chip, External Sense Resistor, Tape-and-Reel, 4.275V VOV
Flip-Chip, External Sense Resistor, Tape-and-Reel, 4.35V VOV
DS2762BX/T&R
Note: Additional VOV options are available, contact Maxim/Dallas Semiconductor sales.
PACKAGE INFORMATION
(For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo.)
Maxim/Dallas Semiconductor cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim/Dallas Semiconductor product.
No circuit patent licenses are implied. Maxim/Dallas Semiconductor reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2003 Maxim Integrated Products S Printed USA
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