MAX1667EAP ,Chemistry-Independent / Level 2 Smart Battery ChargerApplicationsOrdering InformationNotebook Computers Charger Base StationsPART TEMP. RANGE PIN-PACKAG ..
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, ..
MAX4426CSA ,Dual High-Speed 1.5A MOSFET Drivers
MAX4426CSA+ ,Dual High-Speed, 1.5A MOSFET Drivers
MAX4426ESA ,Dual High-Speed 1.5A MOSFET Drivers
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MAX4427CSA ,Dual High-Speed 1.5A MOSFET Drivers
MAX1667EAP
Chemistry-Independent / Level 2 Smart Battery Charger
General DescriptionThe 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.
________________________ApplicationsNotebook 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 CircuitSMBus is a trademark of Intel Corp.
19-1488; Rev 0; 7/99
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 valuesare 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, 10sec).............................+300°C
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 valuesare 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).
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.)
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.)
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
VL LOAD REGULATIONMAX1667 TOC04
LOAD CURRENT (mA)
VL (V)
VL vs. TEMPERATURE
MAX1667 TOC05
TEMPERATURE (°C)
VL (V)
VREF LOAD REGULATION
MAX1667 TOC06
LOAD CURRENT (mA)
REF
(V)
VL LINE REGULATION
MAX1667 TOC03
VDCIN (V)
VL (V)
5V/div
10V
LOAD TRANSIENT
(WITH CHANGE IN REGULATION LOOP)MAX1667TOC02
VDCIN = 18V
ChargingVoltage() = 12,000mV
ChargingCurrent() = 1500mA
1ms/div
CCI
50mV/div
500mA/div
5V/div
10V
LOAD TRANSIENT
(VOLTAGE REGULATION WITH CURRENT LIMIT)MAX1667TOC01
VDCIN = 18V
ChargingVoltage() = 12,000mV
ChargingCurrent() = 1500mA
500μs/div
200mV/div
1.4V
1A/div
__________________________________________Typical Operating Characteristics(Circuit of Figure 7, TA = +25°C, unless otherwise noted.)
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger1.04k6k8k2k10k12k14k18k16k20k
BATT VOLTAGE ERROR
vs. ChargingVoltage() CODEMAX1667 TOC12
ChargingVoltage() CODE
BATT VOLTAGE ERROR (%)1000200030005001500250035004000
LOAD CURRENT ERRORMAX1667 TOC13
CODE
BATT CURRENT ERROR (%)
Typical Operating Characteristics (continued)(Circuit of Figure 7, TA = +25°C, unless otherwise noted.)
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Pin Description
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Smart Battery Charging SystemA 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 DiagramsA 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 TypesTwo 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.
Figure 3. Typical Single Smart Battery System
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
Level 2 Smart Battery ChargerThe 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 SourceFigure 4. Typical Multiple Smart Battery System
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
_______________Detailed Description
Output CharacteristicsThe 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 I0Set 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 SectionThe 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 ControlThe 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 ControlAn 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
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Charger
MAX1667
Chemistry-Independent,
Level 2 Smart Battery Chargeracross the current-sense resistor (RSEN) (which is
between the CS and BATT pins), amplifies it by approx-
imately 5.45, and level shifts it to ground. The full-scale
current is approximately 0.16V/RSEN, and the resolution
is 5mV/RSEN.
The current-regulation loop is compensated by adding a
capacitor to the CCI pin. This capacitor sets the current-
feedback loop’s dominant pole. The GMI amplifier’s out-
put is clamped to between approximately one-fourth
and three-fourths of the REF voltage. While the current is
in regulation, the CCV voltage is clamped to within
80mV of the CCI voltage. This prevents the battery volt-
age from overshooting when the DAC voltage setting is
updated. The converse is true when the voltage is in
regulation and the current is not at the current DAC set-
ting. Since the linear range of CCI or CCV is about 1.5V
to 3.5V (about 2V), the 80mV clamp results in a relatively
negligible overshoot when the loop switches from volt-
age to current regulation or vice versa.
PWM ControllerThe battery voltage or current is controlled by the cur-
rent-mode, PWM, DC-DC converter controller. This con-
troller drives two external N-channel MOSFETs, which
switch the voltage from the input source. This switched
voltage feeds an inductor, which filters the switched rec-
tangular wave. The controller sets the pulse width of the
switched voltage so that it supplies the desired voltage
or current to the battery.
The heart of the PWM controller is the multi-input com-
parator. This comparator sums three input signals to
determine the pulse width of the switched signal, set-
ting the battery voltage or current. The three signals are
the current-sense amplifier’s output, the GMV or GMI
error amplifier’s output, and a slope-compensation sig-
nal, which ensures that the controller’s internal current-
control loop is stable.
The PWM comparator compares the current-sense
amplifier’s output to the lower output voltage of either
the GMV or the GMI amplifier (the error voltage). This
current-mode feedback corrects the duty ratio of the
switched voltage, regulating the peak battery current
and keeping it proportional to the error voltage. Since
the average battery current is nearly the same as the
peak current, the controller acts as a transconductance
amplifier, reducing the effect of the inductor on the out-
put filter LC formed by the output inductor and the bat-
tery’s parasitic capacitance. This makes stabilizing the
circuit easy, since the output filter changes from a com-
plex second-order RLC to a first-order RC. To preserve
the inner current-control loop’s stability, slope compen-
sation is also fed into the comparator. This damps out
perturbations in the pulse width at duty ratios greater
than 50%.
At heavy loads, the PWM controller switches at a fixed
frequency and modulates the duty cycle to control the
battery voltage or current. At light loads, the DC current
through the inductor is not sufficient to prevent the cur-
rent from going negative through the synchronous recti-
fier (Figure 7, M2). The controller monitors the current
through the sense resistor RSEN; when it drops to zero,
the synchronous rectifier turns off to prevent negative
current flow.
MOSFET DriversThe MAX1667 drives external N-channel MOSFETs to
regulate battery voltage or current. Since the high-side
N-channel MOSFET’s gate must be driven to a voltage
higher than the input source voltage, a charge pump is
used to generate such a voltage. The capacitor C7
(Figure 7) charges to approximately 5V through D2
when the synchronous rectifier turns on. Since one side
of C7 is connected to the LX pin (the source of M1), the
high-side driver (DHI) can drive the gate up to the volt-
age at BST (which is greater than the input voltage)
when the high-side MOSFET turns on.
The synchronous rectifier may not be completely
replaced by a diode because the BST capacitor
charges while the synchronous rectifier is turned on.
Without the synchronous rectifier, the BST capacitor
may not fully charge, leaving the high-side MOSFET
with insufficient gate drive to turn on. Use a small MOS-
FET, such as a 2N7002, to guarantee that the BST
capacitor is allowed to charge. In this case, most of the
current at high currents is carried by the Schottky diode
and not by the synchronous rectifier.
Internal Regulator and ReferenceThe MAX1667 uses an internal low-dropout linear regula-
tor to create a 5.4V power supply (VL), which powers its
internal circuitry. VL can supply up to 20mA, less than
10mA powers the internal circuitry, and the remaining
current can power the external circuitry. The current
used to drive the MOSFETs comes from this supply,
which must be considered when calculating how much
power can be drawn. To estimate the current required to
drive the MOSFETs, multiply the total gate charge of
each MOSFET by the switching frequency (typically
250kHz). To ensure VL stability, bypass the VL pin with a
1μF or greater capacitor.
The MAX1667 has an internal, accurate 4.096V refer-
ence voltage. This guarantees a voltage-setting accu-
racy of ±1% max. Bypass the reference with a 1μF or
greater capacitor.
