MAX1660EEE+ ,Digitally Controlled Fuel-Gauge InterfaceFeaturesThe MAX1660 digitally controlled fuel-gauge interface♦ 1% Accuracy over a 600µA to 4A Curre ..
MAX1661EUB ,Serial-parallel/parallel-to-serial converter and load-switch controller with SMBus interfaceApplicationsI/O2 3 8 SMBDATAMAX1662Power-Plane SwitchingMAX1663I/O3 4 7 SMBSUSPoint-of-Load Power-B ..
MAX1662EUB ,Serial-parallel/parallel-to-serial converter and load-switch controller with SMBus interfaceELECTRICAL CHARACTERISTICS(V = +2.7V to +5.5V, T = T to T , unless otherwise noted. Typical values ..
MAX1664CUP ,Active-Matrix Liquid Crystal Display AMLCD SupplyFeaturesThe MAX1664 integrates power-supply and backplane' Integrates All Active Circuitry for Thre ..
MAX1664EUP ,Active Matrix Liquid Crystal Display (AMLCD) SupplyFeaturesThe MAX1664 integrates power-supply and backplane' Integrates All Active Circuitry for Thre ..
MAX1666AEEP , Advanced Lithium-Ion Battery-Pack Protector
MAX4420CSA-T ,High-Speed, 6A MOSFET Driver (Noninverting)General Description
The MAX4420, MAX4429 and MXT429 are single-output
MOSFET drivers designed t ..
MAX4420EPA ,High-Speed, 6A Single MOSFET DriversFeatures
. TTL/CMOS Compatible (IN f 10pA)
. 4.5V to 18V Supply Range (MAX4420/MAX4429)
O 1.59 ..
MAX4420ESA ,High-Speed, 6A Single MOSFET DriversGeneral Description
The MAX4420, MAX4429 and MXT429 are single-output
MOSFET drivers designed t ..
MAX4420ESA ,High-Speed, 6A Single MOSFET Drivers19-0039, Rev Cl 1 1/92
lVl/lXI/VI
High-Speed, 6A Single MOSFE T Drivers
MAX4420ESA ,High-Speed, 6A Single MOSFET DriversFeatures
. TTL/CMOS Compatible (IN f 10pA)
. 4.5V to 18V Supply Range (MAX4420/MAX4429)
O 1.59 ..
MAX4420ESA+ ,High-Speed, 6A MOSFET Driver (Noninverting)Applications
Switching Power Supplies
DC-DC Converters
Motor Controllers
Pin-Diode Drivers
..
MAX1660EEE+
Digitally Controlled Fuel-Gauge Interface
General DescriptionThe MAX1660 digitally controlled fuel-gauge interface
executes two essential functions for rechargeable bat-
tery-pack management: fuel gauging and pack overcur-
rent protection. It accurately monitors a battery pack’s
charge and discharge current flow, and records each
using two independent, on-board Coulomb counters.
Each counter’s contents are externally accessible via a
System Management Bus (SMBus™)-compatible 2-wire
serial interface. An optional third wire interrupts the
microcontroller (µC) when the charge or discharge
counters reach a preset value, or when an overcurrent
condition (charge or discharge) occurs. In the event of
an overcurrent or short-circuit condition, the MAX1660
disconnects the load and alerts its host. The MAX1660’s
flexibility allows accurate fuel gauging for any battery
chemistry, using any desired control algorithm.
The MAX1660 operates with battery voltages from +4V
to +28V and provides two micropower shutdown
modes, increasing battery lifetime. To minimize total
parts count, the device integrates a precision 2.00V
system-reference output, a 3.3V linear-regulator output
that can supply up to 5mA to power external circuitry,
and a power-on reset output for the system µC. The
MAX1660 is available in a 16-pin QSOP package.
________________________ApplicationsSmart-Battery PacksBattery-Pack Fuel Gauging
Battery-Pack Overcurrent Digital Current-Sense
ProtectionInstrumentation
Industrial-Control SystemAnalog-to-Digital
InterfacesConversion
____________________________Features1% Accuracy over a 600µA to 4A Current Range
(RSENSE= 30mΩ)5µV Input Offset Voltage (28µV max)SMBus 2-Wire (Plus Optional Interrupt)
Serial Interface2.00V Precision System Reference Output3.3V Linear-Regulator Output Powers External
CircuitryTwo Micropower Shutdown ModesIndependent 32-Bit Charge and Discharge
Coulomb CountersBattery-Overcharge/Overdischarge ProtectionBattery Short-Circuit/Overcurrent ProtectionOn-Board Power MOSFET Drivers80µA Quiescent Current<1µA Shutdown CurrentSmall 16-Pin QSOP Package
(Same Board Area as 8-Pin SO)
MAX1660
Digitally Controlled
Fuel-Gauge Interface19-1308; Rev 2; 9/06
SMBus is a trademark of Intel Corp.
MAX1660
BATT
AGND
REF
ODI
OCI
GND
SCL
SDA
SHDN
OCOVCC
GND
PACK-
PACK+
RST
INT
ODO
RCS
Typical Operating Circuit
Ordering Information
Pin Configuration appears at end of data sheet.
EVALUATION KIT
AVAILABLE
PARTTEMP RANGE
PIN-
PACKAGE
PKG
CODEMAX1660EEE-40°C to +85°C16 QSOPE16
MAX1660
Digitally Controlled
Fuel-Gauge Interface
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VSHDN= VBATT= 12V, VSCL= VSDA= 3.6V, CREF= 10nF, CVL= 0.1µF, TA
= 0°C to +85°C, unless otherwise noted. Typical valuesare at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
BATT, ODO, OCO, SHDNto GND.........................-0.3V to +30V
SCL, SDA, INT, RSTto GND....................................-0.3V to +6V
REF, ODI, OCI to GND..................................-0.3V to (VL + 0.3V)
VL to GND................................................................-0.3V to +6V
CS to GND...................................................................-2V to +6V
AGND to GND.............................................................-1V to +1V
Continuous Power Dissipation (TA= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C).............667mW
Operating Temperature Range...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +165°C
Lead Temperature (soldering, 10s).................................+300°C
VOCO= 0.4V
VODO= 28V
VSHDN= 3.3V, SOFTSHDN = 0, IVL= 0
VODO= 0.4V
(Note 1)
VCS= 120mV
VCS= 0
0 ≤IREF≤200µA
IREF= 0
VSHDN= 3.3V, SOFTSHDN = 1, IVL= 0
VSHDN≤0.4V
SOFTSHDN = 0, 0 ≤IVL≤5mA
VCS= -120mV
SOFTSHDN = 1, 0 ≤IVL≤5mA
VCS= 0
CONDITIONS12.5OCO Sink Current0.011ODO Off-Leakage Current12.5ODO Sink Current1Propagation Delay-10.011OCI, ODI Input Offset Current-707OCI, ODI Input Offset Voltage
49,50050,00050,500Counts/s0212Charge Coulomb-Counter
Accumulation Rate
49,50050,00050,500Counts/s0212Discharge Coulomb-Counter
Accumulation Rate135
IBATTBATT Supply Current428VBATTBATT Input Voltage Range100CS to AGND Input Resistance
µV/µA1050REF Load Regulation1.962.002.04VREFREF Output Voltage30
0.0213.13.253.4VVLVL Output Voltage3.13.253.6
UNITSMINTYPMAXSYMBOLPARAMETERVINT= 0.4V
VSDA= 0.6V
SHDN
SCL, SDA
SHDN, SCL, SDA
VOCO= 28V2VOLINTOutput Low Sink Current6VOLSDA Output Low Sink Current
0.6V0.8VILInput Low Voltage2.2VIHInput High Voltage0.011OCO Off-Leakage Current
SUPPLY AND REFERENCES
FUEL GAUGE
OVERCURRENT COMPARATOR
INTERFACE-LOGIC LEVELS
MAX1660
Digitally Controlled
Fuel-Gauge Interface
ELECTRICAL CHARACTERISTICS (continued)(VSHDN= VBATT= 12V, VSCL= VSDA= 3.6V, CREF= 10nF, CVL= 0.1µF, TA
= 0°C to +85°C, unless otherwise noted. Typical valuesare at TA= +25°C.)
VTH1, VL rising
VVL= 3V, ISINK= 1.2mA
CONDITIONSVVL= 1V, ISINK= 50µA
VTH2, VL falling
2.752.903.05V1.01.72.2
0.3V0.3VRSTRSTOutput Voltage
VTH1,
VTH2RSTThreshold Voltage
UNITSMINTYPMAXSYMBOLPARAMETERSHDNforced to 28V
SHDNforced to 3.6V
Output forced to 5V25RSTActive Timeout Period100µA0.73.0ISHDNSHDNInput Bias Current0.011SCL, SDA, INT, RSTLeakage
Current
VODO= 0.4V
VODO= 28V
VSHDN= 3.3V, SOFTSHDN = 0, IVL= 0
VODO= 0.4V
(Note 1)
VCS= 120mV
VCS= 0
0 ≤IREF≤200µA
IREF= 0
VSHDN= 3.3V, SOFTSHDN = 1, IVL= 0
VSHDN≤0.4V
SOFTSHDN = 0, 0 ≤IVL≤5mA
VCS= -120mV
SOFTSHDN = 1, 0 ≤IVL≤5mA
VCS= 0
CONDITIONS1OCO Sink Current1ODO Off-Leakage Current1ODO Sink Current-11OCI, ODI Input Offset Current-1010OCI, ODI Input Offset Voltage
49,25050,750Counts/s012Charge Coulomb-Counter
Accumulation Rate
49,25050,750Counts/s012Discharge Coulomb-Counter
Accumulation Rate
IBATTBATT Supply Current428VBATTBATT Input Voltage Range
µV/µA50REF Load Regulation1.962.04VREFREF Output Voltage3.13.4VVLVL Output Voltage3.13.6
UNITSMINTYPMAXSYMBOLPARAMETERVODO= 28VµA1OCO Off-Leakage Current
ELECTRICAL CHARACTERISTICS(VSHDN= VBATT= 12V, VSCL= VSDA= 3.6V, CREF= 10nF, CVL= 0.1µF, TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
SUPPLY AND REFERENCES
FUEL GAUGE
OVERCURRENT COMPARATOR
MAX1660
Digitally Controlled
Fuel-Gauge InterfaceVTH1, VL rising
VVL= 3V, ISINK= 1.2mA
CONDITIONSVVL= 1V, ISINK= 50µA
VTH2, VL falling
2.753.05V1.02.2
0.3V0.3VRSTRSTOutput Voltage
VTH1,
VTH2RSTThreshold Voltage
UNITSMINTYPMAXSYMBOLPARAMETERSHDNforced to 28V
SHDNforced to 3.6V
Output forced to 5V
VINT= 0.4V
VSDA= 0.6V
SHDN
SCL, SDA
SHDN, SCL, SDA
120µA3.0ISHDNSHDNInput Bias Current1SCL, SDA, INT, RSTLeakage
Current2VOLINT, RSTOutput Low Sink Current6VOLSDA Output Low Sink Current
0.6V0.8VILInput Low Voltage2.2VIHInput High Voltage
ELECTRICAL CHARACTERISTICS (continued)(VSHDN= VBATT= 12V, VSCL= VSDA= 3.6V, CREF= 10nF, CVL= 0.1µF, TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
TIMING CHARACTERISTICS(TA
= 0°C to +85°C, unless otherwise noted.)
CONDITIONS4.7tSU:STASTART Condition Setup Time4.7tLOW4tHIGHSCL Serial-Clock High Period
SCL Serial-Clock Low Period4tHD:STASTART Condition Hold Time800tSU:DATSDA Valid to SCL Rising-Edge Setup
Time, Slave Clocking in Data0tHD:DATSCL Falling Edge to SDA Transition1tDVSCL Falling Edge to SDA Valid, Master
Clocking in Data
UNITSMINTYPMAXSYMBOLPARAMETER
INTERFACE-LOGIC LEVELS
MAX1660
Digitally Controlled
Fuel-Gauge InterfaceSCL
START
CONDITION
tHIGH
SDA
tLOWtHD:STA
tSU:STAtSU:DATtHD:DATtSU:DATtHD:DAT
MOST SIGNIFICANT ADDRESS BIT
(A6) CLOCKED INTO SLAVE
A5 CLOCKED
INTO SLAVE
A4 CLOCKED
INTO SLAVE
A3 CLOCKED
INTO SLAVE
Note 1:OCI and ODI are MOSFET inputs. Minimum and maximum limits are for production screening only. Actual performance is
indicated in typical value.
Note 2:Specifications to -40°C are guaranteed by design, not production tested.
CONDITIONS1tDVSCL Falling Edge to SDA Valid, Master
Clocking in Data0tHD:DATSCL Falling Edge to SDA Transition800tSU:DATSDA Valid to SCL Rising-Edge Setup
Time, Slave Clocking in Data4tHD:STASTART Condition Hold Time4.7tSU:STASTART Condition Setup Time4.7tLOWSCL Serial-Clock Low Period4tHIGHSCL Serial-Clock High Period
UNITSMINTYPMAXSYMBOLPARAMETER
TIMING CHARACTERISTICS(TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)Figure 1. SMBus Serial-Interface Timing—Address
SCL
RW BIT
CLOCKED
INTO SLAVE
SDA
tDVtDV
ACKNOWLEDGE
BIT CLOCKED
INTO MASTER
SLAVE PULLING
SDA LOW
MOST SIGNIFICANT BIT
OF DATA CLOCKED
INTO MASTER
Figure 2. SMBus Serial-Interface Timing—Acknowledge
MAX1660
Digitally Controlled
Fuel-Gauge Interface
__________________________________________Typical Operating Characteristics(VBATT= VSHDN= 12V, CREF= 10nF, CVL= 0.1µF, TA= +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. VBATT
MAX1660-01
VBATT (V)
SUPPLY CURRENT (TA = +85°C
TA = +25°C
TA = -40°C
SHUTDOWN SUPPLY CURRENT
vs. VBATT
MAX1660-02
VBATT (V)
SUPPLY CURRENT (
SOFTSHDN = 1
TA = -40°C
TA = +25°C
TA = +85°C
SHUTDOWN SUPPLY CURRENT
vs. VBATT
MAX1660-03
VBATT (V)
SUPPLY CURRENT (
TA = +25°CTA = +85°C
SHDN = GND
TA = -40°C
VL VOLTAGE vs. VL LOAD CURRENT
MAX1660-04
LOAD CURRENT (mA)
VL VOLTAGE (V)TA = +25°C
TA = +85°C
TA = -40°C
REFERENCE VOLTAGE
vs. REFERENCE LOAD CURRENT
MAX1660
LOAD CURRENT (μA)
VOLTAGE (V)
TA = +25°C
TA = +85°C
TA = -40°C
FREQUENCY vs. INPUT VOLTAGE
MAX1660-06
INPUT VOLTAGE (μV)
FREQUENCY (Hz)
INPUT
OFFSET
FREQUENCY
INPUT OFFSET
VOLTAGE
FREQUENCY vs. INPUT VOLTAGE
MAX1660-07
INPUT VOLTAGE (mV)
FREQUENCY (kHz)
IDEAL
MEASURED
CHGCOUNT
DISCOUNT
CONVERSION GAIN vs. INPUT VOLTAGE
MAX1660-08
INPUT VOLTAGE (mV)
CONVERSION GAIN (Hz/mV)
OFFSET
CORRECTED*
275:1
6000:1
UNCORRECTED*
_______________Detailed DescriptionThe MAX1660 measures the cumulative charge into
(charging) and out of (discharging) the system battery
pack and stores the information in one of two internal,
independent charge and discharge counters. It
achieves battery-pack overcharge and overdischarge
protection through a powerful digital compare function
that interrupts the host CPU when the charge or dis-
charge counter reaches a host-programmed value. The
device also informs the host of changes in the direction
of current flow and protects the battery pack from
short-circuit and overcurrent conditions.
The MAX1660 incorporates a 2-wire SMBus-compliant
serial interface, allowing access to charge/discharge
counters and internal registers. An optional third wire
provides an SMBALERT#-compliant interrupt signal, or it
may be used as a simple,stand-alone host interrupt.
Coulomb-Counting InterfaceThe MAX1660’s Coulomb-counting interface monitors
the charge flowing in either the charging or discharging
direction, and counts the Coulombs of charge by incre-
menting either the charge counter (CHGCOUNT) or the
discharge counter (DISCOUNT) accordingly. The num-
ber of counter increments generated per Coulomb of
charge sensed (conversion gain) is given by the follow-
ing equation:
where RCSis the current-sense resistor (see the Typical
Operating Circuit). The gain factor is the constant of
proportionality that relates the counter values stored in
CHGCOUNT and DISCOUNT to the amount of charge
flow into or out of the battery pack. A higher conversion
gain (larger RCS) increases resolution at low currents, = 416.7 103 R Counts
CoulombCCSx
MAX1660
Digitally Controlled
Fuel-Gauge Interface
______________________________________________________________Pin Description
NAMEFUNCTIONINT
Open-Drain Host-Interrupt Output. INTsinks current when active, otherwise high-impedance (see INT
Outputsection). INTis compatible with the SMBus SMBALERT# (the “#” indicates asserted low) signal.
Connect a 100kΩpullup resistor between INTand VL. Leave INTunconnected if host interrupt is not used.SHDNActive-Low Shutdown Input (see Shutdown Modessection)
PINN.C.No Connection. Not internally connected.CSCurrent-Sense Resistor InputOCICharge Overcurrent-Detection Input (see Overcurrent Detectionsection)ODIDischarge Overcurrent-Detection Input (see Overcurrent Detectionsection)REF2.00V Reference Output. Bypass REF to AGND with a 10nF capacitor (see Internal Regulator and Reference
section).AGNDAnalog GroundOCOHigh-Voltage, Open-Drain MOSFET Gate-Driver Output. OCO controls activation of the battery-charge path
(see OCO and ODO Gate Driverssection).ODOHigh-Voltage, Open-Drain MOSFET Gate-Driver Output. ODO controls activation of the battery-discharge
path (see OCO and ODO Gate Driverssection).BATTSupply InputVL3.3V Linear-Regulator Output. Bypass VL with a 0.33µF capacitor to GND (see Internal Regulator and
Referencesection).GNDGroundSCLSerial-Clock Input. Connect a 10kΩresistor between SDA and VL (see SMBus Interfacesection).SDASerial-Data Input/Output. Connect a 10kΩresistor between SDA and VL (see SMBus Interfacesection).RSTActive-Low Reset Output. Connect a 100kΩpullup resistor between RSTand VL. Leave RSTunconnected if
the power-on reset function is not used (see RSTOutputsection).
MAX1660but limits the maximum measurable current. Likewise, a
smaller conversion gain (smaller RCS) decreases resolu-
tion at low currents, but increases the maximum mea-
surable current. A 30mΩcurrent-sense resistor (AC=
12.5 x 103counts per Coulomb) provides a good bal-
ance between resolution and input current range for
many applications. With this current-sense resistance,
the MAX1660 typically measures currents from 600µA to
4A with better than 1% accuracy (see the section
Choosing RCS).
Charge and Discharge CountersFigure 3 shows the functional diagram of the MAX1660’s
Coulomb-counter section. The Coulomb counter’s out-
put increments (but never decrements) one of two inde-
pendent 32-bit counters: CHGCOUNT for charging
currents, and DISCOUNT for discharging currents. By
independently counting the charge and discharge cur-
rents, the MAX1660 can accommodate any algorithm to
account for a battery pack’s energy-conversion efficien-
cy. A 2x1 multiplexer, gated by the configuration word’s
SETCOUNT bit, determines which counter’s contents
are passed to the COUNT register when COUNT
updates. The 32-bit COUNT register is divided into
4 bytes: COUNT0 (the least significant) through
COUNT3 (the most significant). See Table 1 for a
description of the different registers.
CHGCOUNT and DISCOUNT reset to zero whenever a
power-on reset executes, or when the configuration
word’s CLRCOUNTER bit is set. Each counter also
resets any time an overflow condition occurs. The coun-
ters’ 32-bit capacity allows them to continually monitor
4A for almost 24 hours before overflowing (with RCS=
30mΩ). When a counter overflows, it simply clears and
begins counting from 0; no interrupts are generated.
Execute the ReadCount01 and ReadCount23 com-
mands to read the active counter’s contents at any time
(Table 2). Since the Read-Word protocol supports only
16-bit data transfers, issue these commands sequen-
tially to read the entire 32-bit COUNT register. First
issue ReadCount01 to read COUNT0 and COUNT1,
and then issue ReadCount23 to read COUNT2 and
COUNT3. Executing ReadCount01 enables updating of
the COUNT register; the COUNT register updates on
SCL’s falling edge after the command-byte ACK bit
Digitally Controlled
Fuel-Gauge Interface2 x 1 MUX
CHGCOUNTDISCOUNT
DIRINTENABLE
SETCOUNT
COUNTSTATUS
LATCH
LOGIC
ReadCount01
ReadCount23
CLRCOUNTER
DIRCHANGE
OFFSETMEASCHARGESTATUS888
32
MUXOUT
SMB INTERFACE
COUNT0COUNT1COUNT2COUNT3
COULOMB
COUNTER
Figure 3. Coulomb-Counter Functional Diagram
REGISTER NAMEDESCRIPTIONCHGCOUNT
The 32-bit counter that accumulates the number of units of charge that have passed through RCSin the charg-
ing direction since CHGCOUNT was last cleared. CHGCOUNT clears on a power-on reset, or when the config-
uration word’s CLEARCOUNTER bit is set. CHGCOUNT is unaffected by discharging currents.
DISCOUNT
The 32-bit counter that accumulates the number of units of charge that have passed through RCSin the dis-
charging direction since DISCOUNT was last cleared. DISCOUNT clears on a power-on reset, or when the
configuration word’s CLEARCOUNTER bit is set. DISCOUNT is unaffected by charging currents.
COUNT
The 32-bit register that stores the value held in the counter selected by the configuration word’s SETCOUNT bit
when updating has been enabled by the ReadCount01 command. Data transfers to COUNT from the selected
CHGCOUNT or DISCOUNT register whenever the MAX1660’s SMBus interface detects a new command. See
the Charge and Discharge Counterssection.
COMP
The 32-bit register that stores the host-defined COUNT threshold. The contents of COMP are continuously com-
pared with the contents of either CHGCOUNT or DISCOUNT (whichever is selected by the SETCOUNT bit) for
equality. When an equality occurs, the configuration word’s COMPSTATUS bit is set, and an interrupt is gener-
ated (INTgoes low).
Table 1. Register Descriptions
clocks in (Figure 4). COUNT0 returns in the least signifi-
cant byte (LSB), and COUNT1 returns in the most sig-
nificant byte (MSB) of the Read-Word protocol. After
the ReadCount01 command is executed (updating is
enabled), any command executed by the MAX1660
prior to execution of the ReadCount23 command
updates the COUNT contents, potentially corrupting the
data read by ReadCount23 (if a 16th-bit carry occurs).
ReadCount23 disables COUNT updating and then
returns COUNT2 and COUNT3 in the Read-Word proto-
col’s LSB and MSB. To ensure proper execution, issue
these commands in the correct order, with no com-
mands executed between them (ReadCount01 first, fol-
lowed by ReadCount23).
Digital Compare FunctionThe MAX1660’s digital compare function simplifies
implementation of end-of-charge and end-of-discharge
detection, relieving the host from having to constantly
monitor the counters. The host simply programs a value
into the COMPregister, and the MAX1660 generates an
interrupt (INTgoes low) when this condition is met.
Figure 5 shows the MAX1660’s digital compare section
functional diagram. When the digital compare function
is enabled, the MAX1660 continuously compares the
contents of the counter selected by the configuration
word’s SETCOUNT bit with the 32-bit word stored in the
COMP register (Table 1). The 32-bit COMP register is
divided into 4 bytes: COMP0 (the least significant)
through COMP3 (the most significant). When COMP is
equal to MUXOUT, the configuration word’s COMPSTA-
TUS bit is set, and the MAX1660 generates an interrupt
(INTgoes low). The host defines any action taken as a
result of this interrupt. The COMP register contents
remain valid until either the host redefines the value
stored in COMP, or a power-on reset is executed.
Executing a power-on reset disables the digital com-
pare function. Enable the digital compare function by
setting the configuration word’s COMPENABLE bit.
MAX1660
Digitally Controlled
Fuel-Gauge InterfaceCOUNT
REGISTER
UPDATED
SCL
SDA
ANY
COMMAND
BYTE
MAX1660
PULLING
SDA LOW
ACKNOWLEDGE
BIT CLOCKED
INTO MASTER
Figure 4. COUNT Register Updating
COMMAND
NAMEDESCRIPTIONReadCount01
Enables updating of the COUNT register; returns COUNT0 in the LSB and COUNT1 in the MSB of
the Read-Word protocol. COUNT updating remains enabled until the ReadCount23 command is
executed. See the Charge and Discharge Counterssection.
ReadCount23Disables COUNT register updating; returns COUNT2 in the LSB and COUNT3 in the MSB of the
Read-Word protocol. See the Charge and Discharge Counterssection.
ReadStatus()Returns the status word’s contents in the Read-Word protocol’s LSB. The MSB’s contents are all 1s.
See Table 5 for a description of the status bits.
COMMAND
CODE0x82
0x83
0x84
Table 2. Read Word Commands32
DIGITAL
COMPARE
CLR
OCSTATUS
ODSTATUS
CLRINT
POWER-ON RESET
COMPSTATUS
DIRCHANGE
INT
COULOMB
COUNTER
MUXOUTCOMP0COMP1
DIRINTENABLE
COMP2COMP3
CHG
DIS88
SMB INTERFACE
Figure 5. Digital Compare Section Functional Diagram
MAX1660Use the WriteComp01 and WriteComp23 commands to
define the COMP register contents (Table 3). Since the
Write-Word protocol supports only 16-bit data transfers,
sequentially execute these commands to write the
entire 32-bit COMP word. First execute WriteComp01
to write COMP0 and COMP1, and then execute
WriteComp23 to write COMP2 and COMP3. Executing
WriteComp01 internally disables the COMPINT interrupt
and writes the Write-Word protocol’s LSB into COMP0
and its MSB into COMP1. The COMPINT interrupt dis-
ables on SCL’s 18th rising edge during WriteComp01
execution (Figure 6). Executing WriteComp23 writes the
Write-Word protocol’s LSB and MSB into COMP2 and
COMP3, and enables the COMPINT interrupt. The
COMPINT interrupt reenables on the falling edge fol-
lowing SCL’s 36th rising edge during WriteComp23
execution. Disabling the COMPINT interrupt with the
WriteComp01 command prevents an erroneous inter-
rupt, due to incomplete data in the COMP register. To
ensure proper execution, issue these commands in the
correct sequence.
Direction-Change Detection FunctionThe MAX1660’s direction-change detection function
informs the host whenever the current flow changes
direction. When it is used in conjunction with the
MAX1660’s digital compare function and CHARGE-
STATUS bit in end-of-charge and end-of-discharge
detection routines, the host can ensure that the digital
compare function continues to monitor the proper
counter when the current flow changes direction.
The direction-change function is simple: the status
word’s DIRCHANGE bit sets any time the current flow
changes direction. Once DIRCHANGE is set, it remains
set until it is cleared; additional changes in the current-
flow direction do not affect the bit. To clear the DIR-
CHANGE bit, write a 1 to the configuration word’s
CLRINT bit. DIRCHANGE also clears when the
MAX1660 enters soft-shutdown mode and after a
power-on reset. In end-of-charge and end-of-discharge
routines, in which the host must be informed immediate-
ly of a change in current-flow direction, set the configu-
ration word’s DIRINTENABLE bit to generate an interrupt
whenever the status word’s DIRCHANGE bit is set.
Digitally Controlled
Fuel-Gauge Interface
COMMAND
NAMEDESCRIPTIONWriteComp01Disables the COMPINT interrupt; writes the Write-Word protocol’s LSB into COMP0 and its MSB into
COMP1.
WriteComp23Writes the Write-Word protocol’s LSB into COMP2 and its MSB into COMP3, and enables the
COMPINT interrupt.
WriteConfig()Writes the Write-Word protocol’s data bytes into the configuration word. See Table 6 for a descrip-
tion of the configuration bits.
COMMAND
CODE0x00
0x01
0x04
Table 3. Write-Word CommandsSCL
SDA
BOLD LINE INDICATES MAX1660
PULLING SDA LOW
STOP
CONDITION
ACK BIT CLOCKED
INTO HOST
18TH RISING EDGE OF
SCL DURING WriteComp01
WRITE-WORD PROTOCOL
STOP
CONDITION
INTERRUPT
ENABLES ON
SCL’s FALLING
EDGE
ACK BIT CLOCKED
INTO HOST
36TH RISING EDGE OF
SCL DURING WriteComp23
WRITE-WORD PROTOCOL
INTERRUPT
DISABLES ON
SCL’s RISING
EDGE
