MAX1667EAP+ Fast Delivery |IC PHOENIX CO.,LIMITED

MAX1667EAP+ ,Chemistry-Independent, Level 2 Smart Battery ChargerELECTRICAL CHARACTERISTICS(V = 18V, internal reference, 1µF capacitor at REF, 1µF capacitor at VL, ..
MAX1667EAP+ ,Chemistry-Independent, Level 2 Smart Battery ChargerApplicationsOrdering InformationNotebook Computers Charger Base StationsPART TEMP RANGE PIN-PACKAGE ..
MAX1668MEE ,Multichannel Remote/Local Temperature SensorsFeaturesThe MAX1668/MAX1805/MAX1989 are precise multi- Multichannelchannel digital thermometers th ..
MAX1668MEE+ ,Multichannel Remote/Local Temperature SensorsApplications PART TEMP RANGE PIN-PACKAGEMAX1668MEE -55°C to +125°C 16 QSOPDesktop and Notebook Cent ..
MAX1668MEE+T ,Multichannel Remote/Local Temperature SensorsELECTRICAL CHARACTERISTICS(V = +3.3V, STBY = V , configuration byte = X0XXXX00, T = 0°C to +125°C, ..
MAX1668MEE+T ,Multichannel Remote/Local Temperature SensorsFeaturesThe MAX1668/MAX1805/MAX1989 are precise multi-♦ Multichannelchannel digital thermometers th ..
MAX4426CSA ,Dual High-Speed 1.5A MOSFET Drivers
MAX4426CSA+ ,Dual High-Speed, 1.5A MOSFET Drivers
MAX4426ESA ,Dual High-Speed 1.5A MOSFET Drivers
MAX4427CPA ,Dual High-Speed 1.5A MOSFET Drivers
MAX4427CSA ,Dual High-Speed 1.5A MOSFET Drivers
MAX4427CSA ,Dual High-Speed 1.5A MOSFET Drivers

MAX1667EAP+
Chemistry-Independent, Level 2 Smart Battery Charger
General Description
The MAX1667 provides the power control necessary to
charge batteries of any chemistry. All charging functions
are controlled through the Intel System Management Bus
(SMBus™) interface. The SMBus 2-wire serial interface
sets the charge voltage and current and provides thermal
status information. The MAX1667 functions as a Level 2
charger, compliant with the Duracell/Intel Smart Battery
Charger Specification.
In addition to the feature set required for a Level 2 charg-
er, the MAX1667 generates interrupts to signal the host
when power is applied to the charger or when a battery is
installed or removed. Additional status bits allow the host
to check whether the charger has enough input voltage,
and whether the voltage on or current into the battery is
being regulated. This allows the host to determine when
lithium-ion (Li+) batteries have completed the charge with-
out interrogating the battery.
The MAX1667 is available in a 20-pin SSOP with a 2mm
profile height.
________________________Applications
Notebook ComputersCharger Base Stations
Personal Digital AssistantsPhones
____________________________FeaturesCharges Any Battery Chemistry: Li+, NiCd,
NiMH, Lead Acid, etc.SMBus 2-Wire Serial Interface Compliant with Duracell/Intel Smart Battery
Charger Specification Rev. 1.04A, 3A, or 1A (max) Battery Charge Current5-Bit Control of Charge CurrentUp to 18.4V Battery Voltage11-Bit Control of Voltage±1% Voltage AccuracyUp to +28V Input VoltageBattery Thermistor Fail-Safe ProtectionGreater than 95% EfficiencySynchronous Rectifier
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Typical Operating Circuit
PART
MAX1667EAP-40°C to +85°C
TEMP RANGEPIN-PACKAGE
20 SSOP
Ordering Information
SMBus is a trademark of Intel Corp.
19-1488; Rev 1; 5/03
MAX1667
DCIN
REFBST
DHI
DLO
PGND
INT
BATT
SCL
SDA
THM
IOUT
CHARGE SOURCE
AGND
SEL
DACV
CCV
CCI
VDD
HOST
CONTROLLER
SMART
BATTERY
SCL
SDA
INT
GND
BATT+
RSENSE
SCL
SDA
TEMP
BATT-
Pin Configuration appears at end of data sheet.
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDCIN= 18V, internal reference, 1µF capacitor at REF, 1µF capacitor at VL, TA= 0°C to +85°C, unless otherwise noted. Typical values
are at TA= +25°C, unless otherwise noted.)
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.
DCIN to AGND.......................................................-0.3V to +30V
BST to AGND..........................................................-0.3V to +36V
BST, DHI to LX..........................................................-0.3V to +6V
LX, IOUT to AGND..................................................-0.3V to +30V
THM, CCI, CCV, DACV, REF,
DLO to AGND.............................................-0.3V to (VL + 0.3V)
VL, SEL, INT, SDA, SCL to AGND............................-0.3V to +6V
BATT, CS+ to AGND..............................................-0.3V to +20V
PGND to AGND.....................................................-0.3V to +0.3V
SDA, INTCurrent................................................................50mA
VL Current...........................................................................50mA
Continuous Power Dissipation (TA= +70°C)
SSOP (derate 8mW/°C above +70°C)..........................640mW
Operating Temperature Range...........................-40°C to +85°C
Storage Temperature Range.............................-60°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
-0.80.8ChargingVoltage()
= 0x3130 (12,592mV)
and
0x41A0 (16,800mV)
Voltage Accuracy5ChargingCurrent() = 0x0080 (128mA)CS to BATT Single-Count
Current-Sense Voltage019BATT, CS Input Voltage Range350500VL > 5.15V, VBATT= 12VBATT Input Current (Note 1)15VL < 3.2V, VBATT= 12V58High or lowDLO On-Resistance47High or lowDHI On-Resistance467.5V < VDCIN< 28V, logic inputs = VLDCIN Quiescent Current7.528DCIN Input Voltage Range96.597.7In dropoutDHI Maximum Duty Cycle
kHz200250300Not in dropoutOscillator Frequency5.155.45.657.5V < VDCIN< 28V, no loadVL Output Voltage100ILOAD= 0 to 10mAVL Load Regulation3.2045.15VL AC_PRESENT Trip Point
UNITSMINTYPMAXCONDITIONSPARAMETER170400VL > 5.15V, VCS= 12VCS Input Current (Note 1)15VL < 3.2V, VCS= 12V145160175SEL = VL (4A),
ChargingCurrent() = 0x0F80 (3968mA)
CS to BATT Full-Scale
Current-Sense Voltage0 < ISOURCE< 500µAREF Output Voltage= +25°C= TMINto TMAX-1.01.0= +25°C= TMINto TMAX-3.03.0
-1.01.0ChargingVoltage()
= 0x1060 (4192mV)
and
0x20D0 (8400mV)
SWITCHING REGULATOR
SUPPLY AND REFERENCE
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
ELECTRICAL CHARACTERISTICS (continued)
(VDCIN= 18V, internal reference, 1µF capacitor at REF, 1µF capacitor at VL, TA= 0°C to +85°C, unless otherwise noted. Typical values
are at TA= +25°C, unless otherwise noted.)
Note 1:When DCIN is less than 4V, VL is less than 3.2V, causing the battery current to be typically 2µA (CS plus BATT input
current).
Bits11Guaranteed monotonicVDAC Voltage-Setting DAC Resolution
Bits5Guaranteed monotonicCDAC Current-Setting DAC Resolution5579
% of
VREF34.56THM fallingTHM THERMISTOR_UR
Underrange Trip Point
% of
VREF2223.525THM fallingTHM THERMISTOR_HOT
Trip Point
% of
VREF7475.577THM fallingTHM THERMISTOR_COLD
Trip Point
mA/V0.2GMI Amplifier Transconductance
mA/V1.4GMV Amplifier Transconductance
% of
VREF899193THM fallingTHM THERMISTOR_OR
Overrange Trip Point
% of
VDCIN939597BATT risingBATT POWER_FAIL Threshold±80GMV Amplifier Maximum
Output Current±200GMI Amplifier Maximum
Output Current25802001.1V < VCCI< 3.5VCCV Clamp Voltage with
Respect to CCI
UNITSMINTYPMAXCONDITIONSPARAMETER6VSDA= 0.6VSDA Output Low Sink Current-11SDA, SCL Input Bias Current2.2SDA, SCL Input Voltage High 0.8SDA, SCL Input Voltage Low25802001.1V < VCCV< 3.5VCCI Clamp Voltage with
Respect to CCV
ChargingCurrent() = 0x000010µA
ChargingCurrent() = 0x0001
to 0x007F (127mA)
VIOUT= 17V, ChargingCurrent() = 0x0001
to 0x007F (127mA)
VDCIN= 0, VIOUT= 20VµA10IOUT Leakage Current
VIOUT= 0
IOUT Output Current
% of
VDCIN0.5THM THERMISTOR_OR, _COLD,
_HOT, _UR Trip Point Hysteresis
% of
VDCIN1BATT POWER_FAIL Threshold
Hysteresis
ERROR AMPLIFIERS
TRIP POINTS AND LINEAR CURRENT SOURCES
CURRENT- AND VOLTAGE-SETTING DACs
LOGIC LEVELS
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
ELECTRICAL CHARACTERISTICS
(VDCIN= 18V, internal reference, 1µFcapacitor at REF, 1µF capacitor atVL, TA= -40°C to +85°C,unlessotherwise noted.Typical values
are at TA= +25°C. Limits over this temperature range are guaranteed by design.)CS Input Current (Note 1)5VL < 3.2V, VCS= 12V145160175VSEL= VL,
ChargingCurrent() = 0x0F80 (128mA)
CS to BATT Full-Scale
Current-Sense Voltage
-1.01.0ChargingVoltage() = 0x3130 (12,592mV),
ChargingVoltage() = 0x41A0 (16,800mV)Voltage AccuracyBATT Input Current (Note 1)5VL < 3.2V, VBATT= 12V58High or lowDLO On-Resistance47High or lowDHI On-Resistance467.5V < VDCIN< 28V, logic inputs = VLDCIN Quiescent Current96.5In dropoutDHI Maximum Duty Cycle
kHz200250310Not in dropoutOscillator Frequency5.155.45.657.5V < VDCIN< 28V, no loadVL Output Voltage4.0554.1370 < ISOURCE< 500µAREF Output Voltage
UNITSMINTYPMAXCONDITIONSPARAMETER
% of
VREF88.593.5THM fallingTHM THERMISTOR_OR
Overrange Trip Point
% of
VREF73.577.5THM fallingTHM THERMISTOR_COLD
Trip Point0.5SDA, SCL Input Voltage Low2.2SDA, SCL Input Voltage High-11SDA, SCL Input Bias Current
% of
VREF21.525.5THM fallingTHM THERMISTOR_HOT
Trip Point
% of
VREF2.56.5THM fallingTHM THERMISTOR_UR
Underrange Trip Point6VSDA= 0.6VSDA Output Low Sink Current1THM THERMISTOR_OR, _COLD,
_HOT,_UR Trip Point Hysteresis
-3.03.0ChargingVoltage() = 0x1060 (4192mV),
ChargingVoltage() = 0x20D0 (8400mV)
SUPPLY AND REFERENCE
SWITCHING REGULATOR
TRIP POINTS AND LINEAR CURRENT SOURCES
LOGIC LEVELS
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
TIMING CHARACTERISTICS (Figures 1 and 2)
(TA= 0°C to +85°C, unless otherwise noted.)
TIMING CHARACTERISTICS (Figures 1 and 2)
(TA= -40°C to +85°C, unless otherwise noted. Limits over this temperature range are guaranteed by design.)
CONDITIONS1tDVSCL Falling Edge to SDA Valid,
Master Clocking in Data0tHD:DATSCL Falling Edge to SDA Transition4.7tSU:STAStart-Condition Setup Time4.7tLOW4tHIGHSCL Serial-Clock High Period
SCL Serial-Clock Low Period4tHD:STAStart-Condition Hold Time250tSU:DATSDA Valid to SCL Rising-Edge
Setup Time, Slave Clocking in Data
UNITSMINTYPMAXSYMBOLPARAMETER
CONDITIONS4.7tSU:STAStart-Condition Setup Time4.7tLOW
UNITSMINTYPMAXSYMBOLPARAMETER
SCL Serial-Clock Low Period4tHD:STAStart-Condition Hold Time4tHIGHSCL Serial-Clock High Period250tSU: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
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Figure 2. SMBus Serial-Interface Timing—Acknowledge
tDV
SLAVE PULLING
SDA LOW
tDV
MOST SIGNIFICANT BIT
OF DATA CLOCKED
INTO MASTER
ACKNOWLEDGE
BIT CLOCKED
INTO MASTER
RW BIT
CLOCKED
INTO SLAVE
SCL
SDA
START
CONDITION
MOST SIGNIFICANT
ADDRESS BIT (A6)
CLOCKED INTO SLAVE
A5 CLOCKED
INTO SLAVE
A4 CLOCKED
INTO SLAVE
A3 CLOCKED
INTO SLAVE
tHIGHtLOW
tHD:STA
tSU:STAtSU:DATtHD:DAT
SCL
SDA
tSU:DATtHD:DAT
Figure 1. SMBus Serial-Interface Timing—Address
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
VL LOAD REGULATION
MAX1667 TOC04
LOAD CURRENT (mA)
VL (V)
VDCIN = 20V
VL vs. TEMPERATURE
MAX1667 TOC05
TEMPERATURE (°C)
VL (V)
VDCIN = 20V
VREF LOAD REGULATION
MAX1667 TOC06
LOAD CURRENT (mA)
REF
(V)
VL LINE REGULATION
MAX1667 TOC03
VDCIN (V)
VL (V)
NO LOAD
5V/div
10V
LOAD TRANSIENT
(WITH CHANGE IN REGULATION LOOP)
MAX1667TOC02
VDCIN = 18V
ChargingVoltage() = 12,000mV
ChargingCurrent() = 1500mA
1ms/div
VBATT
CCI
CCI
CCI
50mV/div
500mA/div
CCV
CCV
CCV
ILOAD
AVERAGED MEASUREMENT
5V/div
10V
LOAD TRANSIENT
(VOLTAGE REGULATION WITH CURRENT LIMIT)
MAX1667TOC01
VDCIN = 18V
ChargingVoltage() = 12,000mV
ChargingCurrent() = 1500mA
500μs/div
VBATT
CCI
CCV
CCI
CCI
CCI
200mV/div
1.4V
1A/div
CCV
CCV
CCV
ILOAD
AVERAGED MEASUREMENT
__________________________________________Typical Operating Characteristics
(Circuit of Figure 7, TA = +25°C, unless otherwise noted.)
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
04k6k8k2k10k12k14k18k16k20k
BATT VOLTAGE ERROR
vs. ChargingVoltage() CODE
MAX1667 TOC12
ChargingVoltage() CODE
BATT VOLTAGE ERROR (%)
ILOAD = 3mA
VDCIN = 20V
MEASURED AT AVAILABLE
ChargingVoltage() CODES
ILOAD = 600mA1000200030005001500250035004000
LOAD CURRENT ERROR
MAX1667 TOC13
CODE
BATT CURRENT ERROR (%)
VDCIN =20V
VBATT = 12.75V
MEASURED AT AVAILABLE
ChargingCurrent() CODES
Typical Operating Characteristics (continued)
(Circuit of Figure 7, TA = +25°C, unless otherwise noted.)
OUTPUT V-I CHARACTERISTIC
(SWITCHING REGULATOR)
MAX1667 TOC10
LOAD CURRENT (mA)
DROP IN BATT OUTPUT VOLTAGE (%)
VDCIN = 20V
ChargingVoltage() = 17,408mV
ChargingCurrent() = 1920mA
VREF = 4.096V
OUTPUT V-I CHARACTERISTIC
(LINEAR SOURCE)
MAX1667 TOC11
VIOUT (V)
IIOUT
(mA)
VDCIN = 20V
ChargingVoltage() = 17,408mV
ChargingCurrent() = 1 to 127mA
VREF vs. TEMPERATURE
MAX1667 TOC07
TEMPERATURE (°C)
REF
(V)
VDCIN = 20V
EFFICIENCY vs. LOAD CURRENT
(VOLTAGE REGULATION)
MAX1667 TOC08
LOAD CURRENT (mA)
EFFICIENCY (%)
A: VDCIN = 20V, VBATT = 17V
B: VDCIN = 16V, VBATT = 12.75V
C: VDCIN = 20V, VBATT = 12.75V
D: VDCIN = 16V, VBATT = 8.5V
E: VDCIN = 20V, VBATT = 8.5VBED
EFFICIENCY vs. BATT VOLTAGE
(CURRENT REGULATION)
MAX1667 TOC09
BATT VOLTAGE (V)
EFFICIENCY (%)16
A: VDCIN = 16V, ILOAD = 2A
B: VDCIN = 20V, ILOAD = 2A
C: VDCIN = 20V, ILOAD = 600mA
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Pin Description
Linear Current-Source Output1IOUT
Input Voltage for Powering Charger2DCIN
Voltage-Regulation-Loop Compensation Point4CCV
IC Power Supply. 5.4V linear-regulator output from DCIN.3VL
Current-Range Selector. Connecting SEL to VL sets a 4A full-scale current. Leaving SEL
open sets a 3A full-scale current. Connecting SEL to AGND sets a 1A full-scale current.6SEL
Battery Voltage Input and Current-Sense Negative Input8BATT
Current-Sense Positive Input7CS
Current-Regulation-Loop Compensation Point5CCI
+4.096V Reference Voltage Output or External Reference Input9REF
Open-Drain Interrupt Output11INT
Analog Ground10AGND
Thermistor Sense Voltage Input12THM
Serial Data (need external pull-up resistor)14SDA
Power Ground16PGND
Voltage DAC Output Filtering Point15DACV
Serial Clock (need external pull-up resistor)13SCL
High-Side Power MOSFET Driver Output18DHI
Power Connection for the High-Side Power MOSFET Driver20BST
Power Connection for the High-Side Power MOSFET Driver19LX
Low-Side Power MOSFET Driver Output17DLO
FUNCTIONPINNAME
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Smart Battery Charging System
A smart battery charging system, at a minimum, con-
sists of a smart battery and smart battery charger com-
patible with the Smart Battery System specifications
using Intel’s system management bus (SMBus).
Smart Battery System Block Diagrams
A system may use one or more smart batteries. The
block diagram of a smart battery charging system
shown in Figure 3 depicts a single battery system. This
is typically found in notebook computers, video cam-
eras, cellular phones, and other portable electronic
equipment.
Another possibility is a system that uses two or more
smart batteries. A block diagram for a system featuring
multiple batteries is shown in Figure 4. The smart bat-
tery selector is used to connect batteries to either the
smart battery charger or the system, or to disconnect
them, as appropriate. For a standard smart battery, the
following connections must be made: power (the bat-
tery’s positive and negative terminals), SMBus (clock
and data), and safety signal (resistance, typically tem-
perature dependent). Additionally, the system host
must be able to query any battery in the system so it
can display the state of all batteries present in the sys-
tem.
Figure 4 shows a two-battery system where Battery 2 is
being charged while Battery 1 is powering the system.
This configuration may be used to “condition” Battery
1, allowing it to be fully discharged prior to recharge.
Smart Battery Charger Types
Two types of smart battery chargers are defined: Level
2 and Level 3. All smart battery chargers communicate
with the smart battery using the SMBus; the two types
differ in their SMBus communication mode and in
whether they modify the charging algorithm of the
smart battery as shown in Table 1. Level 3 smart bat-
tery chargers are supersets of Level 2 chargers and as
such support all Level 2 charger commands.
SYSTEM
POWER
CONTROL
AC-DC
CONVERTER
(UNREGULATED)
SYSTEM
POWER
SUPPLY
DC (UNREGULATED) / VBATTERY
SAFETY
SIGNAL
VBATTERYDC (UNREGULATED)
VCC
+12V, -12V
SYSTEM HOST
(SMBus HOST)SMART BATTERY
CRITICAL EVENTS
CRITICAL EVENTS
CHARGING VOLTAGE/CURRENT
REQUESTSBATTERY DATA/STATUS REQUESTS
SMART BATTERY
CHARGER
SMBus
MAX1667
Figure 3. Typical Single Smart Battery System
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Level 2 Smart Battery Charger
The Level 2 or “smart-battery-controlled” smart battery
charger interprets the smart battery’s critical warning
messages, and operates as an SMBus slave device
that responds to ChargingVoltage() and Charging-
Current() messages sent to it by a smart battery. The
charger is obliged to adjust its output characteristics in
direct response to the messages it receives from the
battery. In Level 2 charging, the smart battery is com-
pletely responsible for initiating communication and for
providing the charging algorithm to the charger. The
smart battery is in the best position to tell the smart bat-
tery charger how it needs to be charged. The charging
algorithm in the battery may request a static charge
condition or may choose to periodically adjust the
smart battery charger’s output to meet its present
needs. A Level 2 smart battery charger is truly chem-
istry independent, and since it is defined as an SMBus
slave device only, it is relatively inexpensive and easy
to implement.
Table 1. Charger Type by SMBus Mode
and Charge Algorithm Source
Level 3Level 3Slave/Master
Level 3Level 2
Modified from BatteryBattery
Slave Only
SMBus MODECHARGE ALGORITHM SOURCE
Note:Level 1 smart battery chargers are defined in the ver-
sion 0.95a specification. While they can correctly interpret
smart battery end-of-charge messages minimizing over-
charge, they do not provide truly chemistry-independent
charging. They are no longer defined by the Smart Battery
Charger specification and are explicitly not compliant with this
and subsequent Smart Battery Charger specifications.
AC-DC
CONVERTER
(UNREGULATED)
DC (UNREGULATED) / VBATTERY
NOTE: SB 1 POWERING SYSTEM
SB 2 CHARGING
VCC
+12V, -12V
SYSTEM HOST
(SMBus HOST)
SMART BATTERY
SELECTOR
SMBus
SMBus
SMBus
SAFETY SIGNAL
VCHARGE
BATT
SAFETYSIGNAL
BATT
SAFETYSIGNAL
SMART BATTERY 1SMART BATTERY 2
CRITICAL EVENTS
BATTERY DATA/STATUS REQUESTS
SMART BATTERY
CHARGER
SMBus
MAX1667
SYSTEM
POWER
SUPPLY
Figure 4. Typical Multiple Smart Battery System
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
_______________Detailed Description
Output Characteristics
The MAX1667 contains both a voltage-regulation loop
and a current-regulation loop. Both loops operate inde-
pendently of each other. The voltage-regulation loop
monitors BATT to ensure that its voltage never exceeds
the voltage set point (V0). The current-regulation loop
monitors current delivered to BATT to ensure that it
never exceeds the current-limit set point (I0). The cur-
rent-regulation loop is in control as long as BATT volt-
age is below V0. When BATT voltage reaches V0, the
current loop no longer regulates, and the voltage-regu-
lation loop takes over. Figure 5 shows the V-I character-
istic at the BATT pin.
Setting V0 and I0
Set the MAX1667’s voltage and current-limit set points
via the Intel SMBus 2-wire serial interface. The
MAX1667’s logic interprets the serial-data stream from
the SMBus interface to set internal digital-to-analog con-
verters (DACs) appropriately. The power-on-reset value
for V0 and I0 is 18.4V and 7mA, respectively. See Digital
Sectionfor more information.
_____________________Analog Section
The MAX1667 analog section consists of a current-
mode pulse-width-modulated (PWM) controller and two
transconductance error amplifiers—one for regulating
current and the other for regulating voltage. The device
uses DACs to set the current and voltage level, which
are controlled via the SMBus interface. Since separate
amplifiers are used for voltage and current control, both
control loops can be compensated separately for opti-
mum stability and response in each state.
Whether the MAX1667 is controlling the voltage or cur-
rent at any time depends on the battery’s state. If the
battery has been discharged, the MAX1667’s output
reaches the current-regulation limit before the voltage
limit, causing the system to regulate current. As the bat-
tery charges, the voltage rises until the voltage limit is
reached, and the charger switches to regulating voltage.
The transition from current to voltage regulation is done
by the charger and need not be controlled by the host.
Figure 6 shows the MAX1667 block diagram.
Voltage Control
The internal GMV amplifier controls the MAX1667’s out-
put voltage. The voltage at the amplifier’s noninverting
input is set by an 11-bit DAC, which is controlled by a
ChargingVoltage() command on the SMBus (see Digital
Sectionfor more information). The battery voltage is fed
to the GMV amplifier through a 5:1 resistive voltage
divider. The set voltage ranges between 0 and 18.416V
with 16mV resolution. This allows up to four Li+ cells in
series to be charged.
The GMV amplifier’s output is connected to the CCV
pin, which compensates the voltage-regulation loop.
Typically, a series-resistor/capacitor combination can
be used to form a pole-zero doublet. The pole intro-
duced rolls off the gain starting at low frequencies. The
zero of the doublet provides sufficient AC gain at mid-
frequencies. The output capacitor then rolls off the mid-
frequency gain to below 1 to guarantee stability before
encountering the zero introduced by the output capaci-
tor’s equivalent series resistance (ESR). The GMV
amplifier’s output is internally clamped to between one-
fourth and three-fourths of the voltage at REF.
Current Control
An internal 7mA linear current source is used in con-
junction with the PWM regulator to set the battery
charge current. When the current is set to 0, the voltage
regulator is on but no current is available. A current set-
ting between 1mA and 127mA turns on the linear cur-
rent source, providing a maximum of 7mA for trickle
charging. For current settings above 127mA, the linear
current source is disabled and the charging current is
provided by the switching regulator set by the 5-bit cur-
rent-control DAC.
The GMI amplifier’s noninverting input is driven by a 4:1
resistive voltage divider, which is driven by the 5-bit
DAC. With the internal 4.096V reference, this input is
approximately 1.0V at full scale, and the resolution is
31mV. The current-sense amplifier drives the inverting
input to the GMI amplifier. It measures the voltage
BATT
VOLTAGE
AVERAGE CURRENT
THROUGH THE RESISTOR
BETWEEN CS AND BATT
V0 = VOLTAGE SET POINT
I0 = CURRENT-LIMIT SET POINT
Figure 5. Output V-I Characteristic
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Figure 6. Functional Diagram
10k10k10k10k7mA
DCIN
IOUT
REF
REF
THM
AGND
BATT
FROM LOGIC
BLOCK
THERMISTOR_OR
LOGIC
BLOCK
THERMAL
SHUTDOWNTHERMISTOR_COLD
THERMISTOR_HOT
THERM_SHUT
AC_PRESENT
CCV
CCV_LOW
REF
DHI
NOTE:
REF/4 TO 3/4 REF
NOTE: APPROX. REF/4 + VTHRESH
TO 3/4 REF + VTHRESH
3/8 REF = ZERO CURRENT
PGND
FROM LOGIC
BLOCK
AGND
CCV
CCI
GMI
GMV
BST
DLO
AGND
AGND
MIN
BATT
TO LOGIC BLOCK
FROM LOGIC BLOCK
FROM LOGIC BLOCK
VOLTAGE_INREG
CURRENT_INREGTO LOGIC BLOCK
TO LOGIC BLOCKPOWER_FAIL
5-BIT DAC
REF
AGND
AGND
AGND
REF
DACV
DCIN/4.5
SEL
SCL
SDA
INT
THERMISTOR_UR
100k30k3k500Ω
5.4V LINEAR
REGULATOR
CURRENT-SENSE
LEVEL SHIFT AND
GAIN OF 5.5
CLAMP
11-BIT DAC
LEVEL
SHIFTDRIVER
SUMMING
COMPARATOR
BLOCK
CLAMP
TO REF
(MAX)
INTERNAL
4.096V
REFERENCE
DCIN
DRIVER
MAX1667

Partno	Mfg	Dc	Qty	Available	Descript
MAX1667EAP+	MAXIM	N/a	3	avai	Chemistry-Independent, Level 2 Smart Battery Charger
MAX1667EAP+ \|MAX1667EAP	MAX	N/a	90	avai	Chemistry-Independent, Level 2 Smart Battery Charger