MAX2003ACSE ,NiCd/NiMH Battery Fast-Charge ControllersApplications:VSS 8 9 SNSMemory Hold-UpEmergency SwitchoversDIP/SO____ Maxim Integrated Products 1Fo ..
MAX2003ACWE ,NiCd/NiMH Battery Fast-Charge Controllersfeatures as the MAX2003 withan additional pulsed trickle-charge mode to prevent den- Regulationdrit ..
MAX2003CSE ,NiCd/NiMH Battery Fast-Charge Controllersfeatures include optional top-off chargingMAX2003ACSE 0°C to +70°C 16 Narrow SOand direct drivers f ..
MAX2003CWE ,NiCd/NiMH Battery Fast-Charge ControllersELECTRICAL CHARACTERISTICS(V = 4.5V to 5.5V, Figure 1, all measurements are with respect to V , T = ..
MAX2009ETI+ ,1200MHz to 2500MHz Adjustable RF PredistorterFeaturesThe MAX2009 adjustable RF predistorter is designed to♦ Up to 12dB ACPR Improvement*improve ..
MAX200CWP ,+5V RS-232 Transceivers with 0.1uF External CapacitorsApplications
. Three-State TTLICMOS Receiver Outputs
Ordering Information
I mm TEMP. RANGE P ..
MAX5041EAI ,Dual-Phase / Parallelable / Average Current-Mode ControllersFeaturesThe MAX5038/MAX5041 dual-phase, PWM controllers +4.75V to +5.5V or +8V to +28V Input Volta ..
MAX5041EAI ,Dual-Phase / Parallelable / Average Current-Mode ControllersELECTRICAL CHARACTERISTICS(V = +5V, circuit of Figure 1, T = -40°C to +85°C, unless otherwise noted ..
MAX5041EAI ,Dual-Phase / Parallelable / Average Current-Mode ControllersApplicationsServers and WorkstationsOrdering InformationPoint-Of-Load High-Current/High-DensityTele ..
MAX5041EAI+ ,Dual-Phase, Parallelable, Average Current-Mode ControllersApplications ♦ 28-Pin SSOP PackageServers and WorkstationsOrdering InformationPoint-Of-Load High-Cu ..
MAX5043ETN+ ,Two-Switch Power ICs with Integrated Power MOSFETs and Hot-Swap ControllerApplicationsMAX5042ATN -40°C to +125°C 56 TQFN● High-Eficiency Telecom/Datacom Power SuppliesMAX504 ..
MAX5048AAUT ,7.6A, 12ns, SOT23/TDFN MOSFET DriverFeaturesThe MAX5048A/MAX5048B are high-speed MOSFET ♦ Independent Source-and-Sink Outputs fordriver ..
MAX2003ACSE-MAX2003ACWE-MAX2003CSE-MAX2003CWE
NiCd/NiMH Battery Fast-Charge Controllers
General DescriptionThe MAX2003/MAX2003A are fast-charge battery charg-
ers (with conditioning) for NiCd (nickel cadmium) or
NiMH (nickel-metal hydride) rechargeable batteries. The
MAX2003A has the same features as the MAX2003 with
an additional pulsed trickle-charge mode to prevent den-
drite formation in NiMH batteries. Each can be config-
ured as a switch-mode current regulator or as a gating
controller for an external current source. Switch-mode
current regulation provides efficient energy transfer,
reducing power dissipation and the associated heating.
Gating control of an external current source requires
minimal components, saving space and cost.
On-chip algorithms determine charge termination, so the
MAX2003/MAX2003A can be used as stand-alone
chargers. Fast-charge termination is accomplished by
five methods: temperature slope, negative voltage
change, maximum temperature, maximum time, and
maximum voltage. As a safety feature, the start of fast-
charge is inhibited until battery voltage and temperature
are within safe limits. By selecting the appropriate
charge-termination method, a single circuit can be built
with the MAX2003/MAX2003A to fast-charge both NiMH
and NiCd batteries.
The MAX2003/MAX2003A provide a switch-activated
discharge-before-charge option that allows for battery
conditioning and more accurate capacity measure-
ment. Other features include optional top-off charging
and direct drivers for LED status lights.
The MAX2003, in DIP and wide SO packages, is a direct
plug-in replacement for the bq2003. The MAX2003/
MAX2003A also come in a space-saving narrow SO
package. The MAX2003A evaluation kit (MAX2003A
EVKIT-SO) is available to assist in designs.
________________________ApplicationsBattery-Powered Equipment:
Laptop, Notebook, and Palmtop Computers
Handy-Terminals
Portable Consumer Products:
Portable Stereos
Cordless Phones
Backup-Battery Applications:
Memory Hold-Up
Emergency Switchovers
____________________________FeaturesStand-Alone NiCd or NiMH Fast ChargersNew Pulsed Trickle-Charge Mode (MAX2003A only)Provide Switch-Mode, Gated, or Linear Control
RegulationSmall, Narrow SO Package AvailableOn-Chip Fast-Charge Termination Methods:Temperature Slope•Maximum VoltageNegative Delta Voltage•Maximum TimeMaximum TemperatureAutomatically Switch from Fast-Charge to
Trickle-Charge or Top-Off ChargeOptional Discharge-Before-ChargeDirectly Drive Status LEDsOptional Top-Off Charge
MAX2003/MAX2003A
NiCd/NiMH Battery
Fast-Charge Controllers
________________________________________________________________Maxim Integrated Products1
___________________Pin Configuration* Contact factory for dice specifications.
Ordering Information
& the latest literature: http://, .
For small orders, phone 1-800-835-8769.
MAX2003/MAX2003A
NiCd/NiMH Battery
Fast-Charge Controllers_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VCC= 4.5V to 5.5V, Figure 1, all measurements are with respect to VSS, TA= TMINto TMAX, 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.
All Pins to VSS...........................................................-0.3V, +6.0V
Continuous Power Dissipation (TA= +70°C)
Plastic DIP (derate 10.53mW/°C above +70°C)...........842mW
Narrow SO (derate 8.70mW/°C above +70°C).............696mW
Wide SO (derate 9.52mW/°C above +70°C).................762mW
Operating Temperature Range...............................0°C to +70°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10sec).............................+300°C
MAX2003/MAX2003A
NiCd/NiMH Battery
Fast-Charge Controllers
_______________________________________________________________________________________3
ELECTRICAL CHARACTERISTICS (continued)(VCC= 4.5V to 5.5V, Figure 1, all measurements are with respect to VSS, TA= TMINto TMAX, unless otherwise noted.)
TIMING CHARACTERISTICS(VCC= 4.5V to 5.5V, Figure 1, all measurements are with respect to VSS, TA= TMINto TMAX, unless otherwise noted. Typical values
are at VCC= 5.0V, TA= +25°C.)
Note 3:Ratio of actual versus expected timeout (see Table 4). Tested with TM1 = TM2 = floating.
Note 4:To recognize a battery insert signal, VBATmust be greater than VMCVfor at least tBTO.
Note 1:The sense trip levels are determined by an internal resistor divider network that provides a typical difference of 30mV from
SNSHI to SNSLO. Slight variation in this delta is seen if there is a resistor mismatch in the network.
Note 2:Typical variations of Negative Delta Voltage and Thermistor Input Resolution parameters are less than ±4mV.
MAX2003/MAX2003A
NiCd/NiMH Battery
Fast-Charge Controllers_______________________________________________________________________________________
______________________________________________________________Pin Description
MAX2003/MAX2003A
NiCd/NiMH Battery
Fast-Charge Controllers
_______________________________________________________________________________________5Figure 1. Switched-Mode Operation for NiMH Batteries with ΔT/Δt Termination
MAX2003/MAX2003A
NiCd/NiMH Battery
Fast-Charge Controllers_______________________________________________________________________________________
Detailed DescriptionThe MAX2003/MAX2003A is a fast-charge battery charg-
er that uses several methods of charge termination. The
device constantly monitors your choice of the following
conditions to determine termination of fast-charge:
Negative Delta Voltage (-ΔV)
Rate-of-Change of Temperature (ΔT/Δt)
Maximum Voltage
Maximum Time
Maximum Temperature
Figure 2 shows the block diagram for the MAX2003/
MAX2003A.
The first step in creating a fast-charge battery-charger
circuit is to determine what type of battery will be used
and what conditions the battery manufacturer recom-
mends for termination of fast-charge. The type of bat-
tery (NiCd or NiMH) and charge rate determine which
method(s) of termination should be used.
The charging characteristics of NiMH batteries are simi-
lar to those of NiCd batteries, but there are some key dif-
ferences that affect the choice of charge-termination
method. Since the type of charge termination can be dif-
ferent for NiCd and NiMH batteries, it may not always be
possible to use the same circuit for both battery types.
A comparison of the voltage profiles for NiCd and NiMH
batteries (shown in Figure 3) reveals that NiCd batteries
display a larger negative drop in voltage at the end of
charge than do NiMH batteries. Therefore, the negative
delta voltage detection (-ΔV) method of terminating
fast-charge should only be used for NiCd batteries.
This termination method can cause errors in NiMH bat-
teries, since the drop in voltage at full capacity is not as
great, and may lead to an overcharged battery.
Figure 4 shows the temperature profiles of the two
types of batteries. During the first 80% of the charge
cycle, the NiCd battery temperature slowly rises. The
NiMH battery temperature rises more rapidly during this
period. As the cells approach 90% of capacity, the
temperature of the NiCd cells rises more rapidly. When
the cells approach full capacity, the rates-of-rise of
temperature are comparable for both battery types. The
rate of temperature change (ΔT/Δt) can therefore be
used to terminate fast-charge for both NiCd and NiMH
batteries; fast-charge is terminated when the rate of
temperature rise exceeds a preset rate.
Table 1 provides some guidelines to help in the selec-
tion of the proper fast-charge termination method, but
the manufacturer’s recommendations take priority in
case of conflict.
Figure 1 shows a standard application circuit for a
switched-mode battery charger that charges NiMH bat-
teries at a rate of C. Though this circuit is shown for
NiMH batteries, it can be used for NiCd batteries (see
Table 1b). The description below will use this standard
application to explain, in detail, the functionality of the
MAX2003/MAX2003A.
Battery Sense VoltageThe BAT pin measures the per-cell voltage of the bat-
tery pack; this voltage is used to determine fast-charge
initiation and termination. The voltage is determined by
the resistor-divider combination RB1and RB2, shown in
Figure 1, where:
Total Number of Cells = (RB1/ RB2) + 1
Since BAT has extremely high input impedance (50MΩ
minimum), reasonable values can be selected for resis-
tors RB1and RB2. These values, however, must not be
low enough to drain the battery or high enough to
unduly lengthen the time constant of the signal going to
the BAT pin. The total resistance value from the positive
to negative terminal of the battery (RB1+ RB2) should
be between 100kΩand 500kΩto prevent these prob-
lems.
A simple RC lowpass filter (RB, CB) may be needed to
give a more accurate reading by removing any noise
that may be present. Remember that the RC time delay
from the cell to BAT must not exceed 200ms or the bat-
tery detection logic might not function properly (RBx< 200ms).
MAX2003/MAX2003A
NiCd/NiMH Battery
Fast-Charge Controllers
_______________________________________________________________________________________7Figure 2. Block Diagram
Figure 3. Voltage-Charge Characteristics of NiCd and NiMH
Batteries
Figure 4. Temperature-Charge Characteristics of NiCd and
NiMH Batteries
MAX2003/MAX2003A
Temperature MeasurementThe MAX2003/MAX2003A employs a negative tempera-
ture-coefficient (NTC) thermistor to measure the bat-
tery’s temperature. This temperature value can be used
to determine start and termination of fast-charge. The
two temperature conditions that can be used for fast-
charge termination are:
Maximum Temperature
Rate-of-Change of Temperature (ΔT/Δt)
Figure 5 shows the various temperature cutoff points and
the typical voltages that the device will see at the TS pin.
VLTF(low-temperature fault voltage) refers to the volt-
age at TS when the battery temperature is too low, and
VHTF(high-temperature fault voltage) refers to the high-
temperature cutoff. If the voltage is outside these limits,
the MAX2003/MAX2003A will not enter fast-charge
mode. After fast-charge is initiated, the termination
point for high-temperature termination is VTCO(temper-
ature cutoff voltage), rather than VHTF. See Figure 5 for
TEMP LED status.
VLTFis set internally at 0.4VCC, so (with a 5V supply)
VLTFis 2V. VTCOis set up using external resistors to
determine the high-temperature cutoff after fast-charge
begins. VHTFis internally set to be (VLTF- VTCO) / 8
above VTCO.
Thermistors are inherently nonlinear with respect to
temperature. This nonlinearity is especially noticed
when ΔT/Δt measurements are made to determine
charge termination. The simplest way around this is to
place a resistor-divider network in parallel with the ther-
mistor (Figure 6) to reduce the effects of nonlinearity.
The lowpass filter (RT, CT) placed on the TS pin attenu-
ates high-frequency noise on the signal seen by TS.
Charge PendingBefore fast-charge is initiated, the cell voltage and tem-
perature of the battery pack must be within the
assigned limits. If the voltage or temperature is outside
these limits, the device is said to be in a “charge-pend-
ing” state. During this mode, the CHG pin will cycle low
(LED on) for 0.125sec and high (LED off) for 1.375sec.
Fast-charge is normally initiated if the cell voltage is
greater than VEDV(end-of-discharge voltage). If the cell
voltage is too low (below VEDV), the device waits until
the trickle current brings the voltage up before fast-
charge is initiated. VEDVis set internally at 0.2VCC, so
(for a 5V supply) VEDVis 1V.
If the temperature of the cell is not between VLTFand
VHTFthe device is also in a charge-pending state (see
Temperature Measurementsection).
Initiate Fast-ChargeIf the MAX2003/MAX2003A are out of the charge-pend-
ing state, fast-charge can be initiated upon one of the
following conditions:
Battery Replacement
Applying Power to the MAX2003/MAX2003A
(battery already present)
Digital Control Signal
During fast-charge, the CHG pin will be continuously
low (LED on). For the initial period of fast-charge (the
hold-off time), the voltage charge-termination methods
are disabled. The hold-off time is a function of the
charge rate selected by TM1 and TM2 (see Table 4).
NiCd/NiMH Battery
Fast-Charge Controllers_______________________________________________________________________________________Figure 5. Temperature Measurement Scale
Battery ReplacementBefore a battery is inserted, the BAT pin is pulled high-
er than the maximum cell voltage (MCV) by the resistor
(RTR) and the divider network (RB1/RB2) (Figure 1).
When the battery is inserted, the voltage per cell at BAT
falls from the default voltage to the battery voltage.
Fast-charge is initiated on a falling edge when the BAT
voltage crosses the voltage on MCV.
Applying Power to the MAX2003/MAX2003A
(battery already present)There may be some cases where a battery is connect-
ed before power is applied to the MAX2003/
MAX2003A. When power is applied, the device goes
into reset mode for approximately 1.5sec and then
samples the CCMD and DCMD pins. Its charge status
is determined by the voltage at both the CCMD and
DCMD pins. Table 2 summarizes the various conditions
the MAX2003/MAX2003A might see on power-up.
Table 2 shows that the MAX2003/MAX2003A can be
set-up for fast-charge on power-up by making sure
CCMD and DCMD are at the same potential. If fast-
charge on power-up is not desired, make sure CCMD
and DCMD are at different logic levels during power-
up, and use a digital signal to control fast-charge (see
Digital Controlsection).
Digital ControlThe CCMD pin can be used to initiate fast-charge. This is
useful when neither the power supply nor the battery can
be removed from the charger. The CCMD signal needed
to initiate fast-charge depends on the potential at DCMD.
If DCMD is low, a rising edge on CCMD initiates fast-
charge. If DCMD is high, a falling edge on CCMD pro-
vides the fast-charge signal. Table 3 summarizes the
conditions used to start fast-charge.
Discharge-Before-Charge (optional)The discharge-before-charge function is optional and
can be used to condition old batteries. It is especially
useful in NiCd batteries, since it alleviates the voltage
depression problems associated with partially dis-
charged NiCd cells. The discharge-before-charge
function is initiated by a rising edge into DCMD.
When the digital signal is applied, the DIS pin will be
pulled high, turning on the attached circuit and dis-
charging its battery. The discharge process continues
until the single cell voltage drops below 0.2VCC. During
the discharge phase, the CHG pin will be low (LED on)
for 1.375sec and high (LED off) for 0.125sec.
The MAX2003/MAX2003A does not control the current
during discharge-before-charge. If the discharge rate
is too great, the battery could overheat and be dam-
aged. The battery manufacturer will be able to specify
a safe discharge rate, but a rate of C or slower is typi-
cally acceptable. It is also important to choose compo-
nents (Q2, RDIS) that are rated for that particular
discharge rate. Since the gate-source drive for Q2 can
be as low as 4.5V, use a logic-level MOSFET.
Fast-Charge CurrentThe fast-charge current can be generated using two
categories of circuits:
Circuits with a sense resistor (RSNS)
Circuits without sense resistor (SNS tied to VSS)
Circuits with SNS ResistorThe standard application circuit of Figure 1 uses an
inductor and a switched mode of operation to supply
the current. The charge current is determined by the
sense resistor placed between the negative terminal of
the battery (SNS) and ground (VSS).
The SNS pin is the input to a comparator with hystere-
sis. If the voltage at SNS drops below 0.044VCC, the
MOD pin is turned on. If the SNS voltage is above
0.050VCC, MOD is turned off. In the switched mode of
MAX2003/MAX2003A
NiCd/NiMH Battery
Fast-Charge Controllers
_______________________________________________________________________________________9
MAX2003/MAX2003Aoperation, the SNS voltage ramps between 0.044VCC
and 0.050VCC, which is 220mV and 250mV when VCC
is 5V (Figure 7). The average voltage at SNS, therefore,
is 235mV, and can be used to calculate the charge cur-
rent as follows:
ICHARGE= 0.235V / RSNS
where RSNSis the sense resistor and ICHARGEis the
charge current required.
Circuits without SNS ResistorIn some applications (shown later), SNS is tied directly
to ground. In these cases, the MOD pin remains on
until any one charge-termination condition is exceeded
(Figure 8). A reasonable external current limit (such as
a current-limited DC source) must be provided for
these applications, to prevent battery damage due to
excessive charge currents.
Charge TerminationThe MAX2003 has several charge-termination methods.
The termination method selected depends on the type
of battery and charge rate used. Table 1 summarizes
the conditions used to terminate fast-charge with differ-
ent battery types and charge rates.
Temperature Rate TerminationThe Temperature Rate Termination (ΔT/Δt) method ter-
minates fast-charge when a particular rate-of-change in
temperature is exceeded. As the battery begins fast-
charge, its temperature increases at a slow rate. When
the battery nears full capacity, this rate of temperature
change increases. When the rate of temperature
change exceeds a preset number, fast-charge is termi-
nated. This method of fast-charge termination can be
used for both NiCd and NiMH batteries.
The MAX2003 samples the voltage at the TS pin every 34
seconds and compares it with a value taken 68 seconds
earlier. Since an NTC thermistor is used for temperature
measurements, a gradual rise in temperature will result in
successively lower voltage readings. If the new reading is
more than 0.0032VCC(16mV for VCC= 5V) below the old
reading, fast-charge is terminated.
The MAX2003A varies the sampling interval as a function
of charge rate (Table 4). As the charge rate increases,
the sampling interval decreases, thereby allowing more
accurate termination of fast charge.
Note: This method of charge termination is valid only
when the battery’s temperature is between VLTFand
VTCO(Figure 5).
NiCd/NiMH Battery
Fast-Charge Controllers______________________________________________________________________________________Figure 7. Current Regulation with an SNS Resistor
