Analogic AAT3697 2a lithium-ion/polymer battery charger Datasheet

AAT3697
2A Lithium-Ion/Polymer Battery Charger
General Description
Features
The AAT3697 BatteryManager is a highly integrated single-cell lithium-ion/polymer battery charger
IC designed to operate with AC adapter inputs. It
requires a minimum number of external components. The AAT3697 precisely regulates battery
charge voltage and current for 4.2V lithiumion/polymer battery cells. Adapter charge current
rates can be programmed up to 2.0A. An active
thermal management system regulates the fast
charge constant current for all ambient temperature and input vs. output voltage conditions.
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•
Battery temperature and charge state are fully
monitored for fault conditions. In the event of an
over-voltage or over-temperature failure, the
device will automatically shut down, thus protecting
the charging device, control system, and the battery under charge. Status monitor output pins are
provided to indicate the battery charge status by
directly driving two external LEDs. A serial interface
output is available to report 12 various charging
status states to a microcontroller.
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BatteryManager™
Input Voltage Range: 4.0V to 5.5V
Up to 2.0A Charging Current
Adapter Present Indicator (ADPP#)
High Level of Integration with Internal:
— Charging Device
— Reverse Blocking Diode
— Current Sensing
Active Thermal Loop Charge Reduction
Automatic Recharge Sequencing
Battery Temperature Monitoring
Full Battery Charge Auto Turn-Off / Sleep Mode
Over-Voltage, Over-Current, and OverTemperature Protection
Power On Reset and Soft Start
Serial Interface Status Report
12-Pin 3x3mm TDFN Package
-40°C to +85°C Temperature Range
Applications
The AAT3697 is available in a Pb-free, thermallyenhanced, space-saving 12-pin TDFN 3x3mm
package and is rated over the -40°C to +85°C temperature range.
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Cellular Telephones
Digital Still Cameras
Hand Held PCs
MP3 Players
Personal Data Assistants (PDAs)
Other Lithium-Ion/Polymer Battery-Powered
Devices
Typical Application
BATT+
Adapter
Present
ADPP#
BAT
VADP
Enable
EN
COUT
10μF
RT1
DATA
Serial Interface
+
BATT-
AAT3697
TS
CT
Adapter
ADP
ADPSET
CIN
10μF
STAT1
GND
CT
0.1μF
TEMP
STAT2
RSET
RT2
RB1
RB2
Battery
Pack
LED1
LED2
3697.2007.02.1.1
1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Pin Descriptions
Pin #
Name
Type
Function
1
BAT
Out
2
ADP
In
3
GND
Ground
4
EN
In
5
ADPP#
Out
6
TS
In/Out
7
DATA
Out
Status report to microcontroller via serial interface: open drain.
8
STAT2
Out
Battery charge status indicator pin to drive an LED: active low, open drain.
9
STAT1
Out
Battery charge status indicator pin to drive an LED: active low, open drain.
10
CT
In/Out
11
N/C
12
ADPSET
Battery charging and sensing.
Adapter input.
Ground connection.
Enable pin. Logic high enables the IC..
Adapter present indicator. This pin is open drain until ADP pin reaches
threshold.
Battery temperature sense input.
Timing capacitor to adjust internal watchdog timer. Set maximum charge
time for adapter powered trickle, CC, and CV charge modes. If timing
function is not needed, terminate this pin to ground.
No connection.
In/Out
EP
Use resistor at this pin to set adapter charging current.
Exposed paddle (bottom); connect to GND directly beneath package.
Pin Configuration
TDFN33-12
(Top View)
BAT
ADP
GND
EN
ADPP#
TS
2
1
12
2
11
3
10
4
9
5
8
6
7
ADPSET
N/C
CT
STAT1
STAT2
DATA
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Absolute Maximum Ratings1
Symbol
VP
VP
VN
TJ
TLEAD
Description
ADP Input Voltage, <30ms, Duty Cycle <10%
ADP Input Voltage, Continuous
BAT, TS, ADPSET, ADPP#, DATA, CT, EN, STAT1, STAT2
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads)
Value
Units
-0.3 to 7.0
-0.3 to 6.0
-0.3 to VP + 0.3
-40 to 150
300
V
V
V
°C
°C
Value
Units
50
2.0
°C/W
W
Thermal Information
Symbol
θJA
PD
Description
Maximum Thermal Resistance2
Maximum Power Dissipation
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Mounted on an FR4 board.
3697.2007.02.1.1
3
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Electrical Characteristics1
VADP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Conditions
Operation
ADP
VADPP
Adapter Voltage Range
Adapter Present Threshold Voltage
Under-Voltage Lockout (UVLO)
VUVLO
UVLO Hysteresis
IOP
Operating Current
ISLEEP
Sleep Mode Current
Reverse Leakage Current from
ILeakage
BAT Pin
Voltage Regulation
VBAT_EOC1 End of Charge Voltage Accuracy
ΔVCH/VCH Output Charge Voltage Tolerance
VMIN
Preconditioning Voltage Threshold
VRCH
Battery Recharge Voltage Threshold
Current Regulation
ICH
Charge Current
ΔICH/ICH
Charge Current Regulation Tolerance
VADPSET
ADPSET Pin Voltage
KIA
Current Set Factor: ICH/IADPSET
Charging Devices
Adapter Charging Transistor
RDS(ON)
On Resistance
Min
Typ
4.0
5.5
Charge Current = 100mA
VBAT = 4.25V
3.0
3.0
150
0.3
0.3
VBAT = 4V, ADP Pin Open
1.0
Rising Edge
4.158
2.8
Max Units
4.20
0.5
3.0
1.5
1.0
μA
4.242
3.15
VBAT_EOC - 0.1
100
VIN = 5.5V
0.2
0.25
V
%
V
V
2000
mA
%
V
0.35
Ω
10
2.0
4000
CC Mode
V
V
V
mV
mA
μA
1. The AAT3697 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -40°C to +85°C
temperature range is guaranteed by design.
4
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Electrical Characteristics1
VADP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Description
Logic Control / Protection
VEN(H)
Input High Threshold
VEN(L)
Input Low Threshold
VADPP#
Output Low Voltage
Preconditioning Plus Constant
TC
Current Mode Time Out
TP
Preconditioning Time Out
TV
Constant Voltage Mode Time Out
VSTAT
Output Low Voltage
ISTAT
STAT Pin Current Sink Capability
VOVP
Over-Voltage Protection Threshold
ITK/ICH
Pre-Charge Current
ITERM/ICH
Charge Termination Threshold
Current
VTS1
High Temperature Threshold
VTS2
Low Temperature Threshold
IDATA
DATA Pin Sink Current
IADPP#
ADPP# Current Sink
VDATA(H)
Input High Threshold
VDATA(L)
Input Low Threshold
SQPULSE
Status Request Pulse Width
tPERIOD
System Clock Period
fDATA
Data Output Frequency
TREG
Thermal Loop Regulation
TLOOP_IN
Thermal Loop Entering Threshold
TLOOP_OUT Thermal Loop Exiting Threshold
Over-Temperature Shutdown
TOVSD
Threshold
Conditions
Min
Typ
Max
Units
0.4
0.4
V
V
V
1.6
ADPP# Pin Sinks 500μA
CCT = 100nF, VADP = 5.5V
3.0
Hour
CCT = 100nF, VADP = 5.5V
CCT = 100nF, VADP = 5.5V
STAT Pin Sinks 4mA
25
3.0
8.0
4.4
10
Minute
Hour
V
mA
V
%
7.5
%
VADP = 5.5V
VADP = 5.5V
DATA Pin is Active Low State
ADPP# Pin is Active Low State
0.4
29.1
58.2
3
30
60
30.9
61.8
50
20
90
110
85
%VADP
%VADP
mA
mA
V
V
ns
μs
kHz
°C
°C
°C
145
°C
8
1.6
0.4
Status Request
200
1. The AAT3697 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -40°C to +85°C
temperature range is guaranteed by design.
3697.2007.02.1.1
5
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Typical Characteristics
Charge Current vs. RSET
Battery Voltage vs. Supply Voltage
10000
4.242
VBAT (V)
ICH (mA)
4.221
1000
4.200
4.179
100
4.158
1
10
100
4.5
4.75
RSET (kΩ
Ω)
5.0
5.25
5.5
Supply Voltage (V)
End of Charge Voltage Regulation
vs. Temperature
Preconditioning Threshold
Voltage vs. Temperature
4.242
3.05
3.04
3.03
3.02
VMIN (V)
VBAT_EOC (V)
4.221
4.200
3.01
3.00
2.99
2.98
4.179
2.97
2.96
4.158
-50
2.95
-25
0
25
50
75
-50
100
-25
Temperature (°°C)
0
25
50
75
100
Temperature (°°C)
Pre-Charge Current vs. Temperature
Charge Current vs. Temperature
(ADPSET = 8.06kΩ
Ω)
(ADPSET = 8.06kΩ
Ω)
1100
120
1080
1060
1040
ICH (mA)
ITK (mA)
110
100
1020
1000
980
960
90
940
920
80
-50
900
-25
0
25
50
Temperature (°C)
6
75
100
-50
-25
0
25
50
75
100
Temperature (°C)
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Typical Characteristics
Charge Current vs. Battery Voltage
Charge Current vs. Supply Voltage
(ADPSET = 8.06kΩ
Ω; VIN = 5.0V)
(ADPSET = 8.06kΩ
Ω)
1.2
1200
1.0
1000
0.8
800
ICH (mA)
ICH (A)
VBAT = 3.3V
0.6
0.4
VBAT = 3.9V
600
VBAT = 3.5V
400
200
0.2
0
0.0
2.5
2.9
3.3
3.7
4.1
4.5
4.5
4.75
Battery Voltage (V)
5.25
5.5
5.75
6.0
Supply Voltage (V)
VIH vs. Supply Voltage
EN Pin (Rising)
VIL vs. Supply Voltage
EN Pin (Falling)
1.4
1.4
1.3
1.3
1.2
1.2
1.1
1.1
-40°C
1.0
+25°C
VIH (V)
VIH (V)
5.0
0.9
0.8
0.7
-40°C
1.0
+25°C
0.9
0.8
0.7
+85°C
0.6
0.6
+85°C
0.5
0.5
0.4
0.4
4.2
4.4
4.6
4.8
5.0
5.2
5.4
5.6
5.8
6.0
4.2
4.4
4.6
Supply Voltage (V)
4.8
5.0
5.2
5.4
5.6
5.8
6.0
Supply Voltage (V)
Operating Current vs. ADPSET Resistor
Counter Timeout vs. Temperature
(CT = 0.1µF)
10
0.80
8
Counter Timeout (%)
0.90
IOP (mA)
0.70
0.60
Constant Current
0.50
0.40
0.30
0.20
Pre-Conditioning
0.10
6
4
2
0
-2
-4
-6
-8
0.00
1
10
100
ADPSET Resistor (kΩ
Ω)
3697.2007.02.1.1
1000
-10
-50
-25
0
25
50
75
100
Temperature (°°C)
7
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Typical Characteristics
2.0
100
1.8
90
1.6
80
1.4
Precondition Timeout
1.2
1.0
0.8
Precondition + Constant Current Timeout
or Constant Voltage Timeout
0.6
0.4
70
60
50
30
20
10
0.0
0
2
4
6
Time (hours)
8
VTS2
40
0.2
0
8
High and Low Temperature
Threshold vs. Temperature
VTS (% VADP)
Capacitance (μ
μF)
CT Pin Capacitance vs. Counter Timeout
10
VTS1
-50
-25
0
25
50
75
100
Temperature (°°C)
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Functional Block Diagram
CV/
Precharge
Constant
Current
Charge
Control
4.2V
BAT
OverTemperature
Protection
Current
Compare
ADPSET
UVLO
ADP
ADPP#
Voltage
Sense
STAT1
STAT2
DATA
Reverse Blocking
TS
Charge
Status
Serial
Data
IC enable
Watchdog
Timer
CT
EN
GND
Functional Description
The AAT3697 is a highly integrated single-cell lithium-ion/polymer battery charger IC designed to
operate with standard AC adapter input sources,
while requiring a minimum number of external
components. The AAT3697 precisely regulates
battery charge voltage and current for 4.2V lithiumion/polymer battery cells.
The adapter charge input constant current level
can be programmed up to 2.0A for rapid charging
applications. The AAT3697 is rated for operation
from -40°C to +85°C. In the event of operating
ambient temperatures exceeding the power dissipation abilities of the device package for a given
constant current charge level, the charge control
will enter into thermal regulation. When the system
thermal regulation becomes active, the programmed constant current charge amplitude will
be automatically reduced to a safe level for the current operating condition. Should the ambient operating temperature drop below the thermal loop
threshold, the system will automatically resume
charging at the full programmed constant current
3697.2007.02.1.1
level. This intelligent thermal management system
permits the AAT3697 to operate and safely charge
a battery cell over a wide range of ambient conditions while maximizing the greatest possible
charge current for the given set of conditions.
Status monitor output pins are provided to indicate
the battery charge state by directly driving two
external LEDs. A serial interface output is also
available to report any one of 12 distinct charge
states to the system microcontroller.
Battery temperature and charge state are fully
monitored for fault conditions. In the event of an
over-voltage or over-temperature failure, the
device will automatically shut down, thus protecting
the charging device, control system, and the battery under charge. In addition to internal charge
controller thermal protection, the AAT3697 also
provides a temperature sense feedback function
(TS pin) from the battery to shut down the device in
the event the battery exceeds its own thermal limit
during charging. All fault events are reported to the
user either by the simple status LEDs or via the
DATA pin function.
9
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Charge Complete Voltage
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
I = Max CC
Regulated Current
Constant Current Mode
Voltage Threshold
Trickle Charge and
Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
Charging Operation
The AAT3697 has four basic modes for the battery
charge cycle: pre-conditioning / trickle charge; constant current / fast charge; constant voltage; and
end of charge (see Figure 1).
Battery Preconditioning
Before the start of charging, the AAT3697 checks
several conditions in order to assure a safe charging
environment. The input supply must be above the
minimum operating voltage, or under-voltage lockout
threshold (VUVLO), for the charging sequence to
begin. Also, the cell temperature, as reported by a
thermistor connected to the TS pin from the battery,
must be within the proper window for safe charging.
When these conditions have been met and a battery
is connected to the BAT pin, the AAT3697 checks the
state of the battery. If the cell voltage is below the preconditioning voltage threshold (VMIN), the charge
control begins preconditioning the cell.
The battery preconditioning trickle charge current is
equal to the fast charge constant current divided by
10. For example, if the programmed fast charge
current is 1.5A, then the preconditioning mode
(trickle charge) current will be 150mA. Cell preconditioning is a safety precaution for deeply discharged battery cells and also aids in limiting power
dissipation in the pass transistor when the voltage
across the device is at the greatest potential.
Fast Charge / Constant Current Charging
Battery cell preconditioning continues until the voltage on the BAT pin exceeds the preconditioning
voltage threshold (VMIN). At this point, the AAT3697
begins the constant current fast charging phase.
10
The fast charge constant current (ICH) amplitude is
programmed by the user via the RSET resistor. The
AAT3697 remains in the constant current charge
mode until the battery reaches the voltage regulation point, VBAT_EOC.
Constant Voltage Charging
The system transitions to a constant voltage charging mode when the battery voltage reaches the
output charge regulation threshold (VBAT_EOC) during the constant current fast charge phase. The
regulation voltage level is factory programmed to
4.2V (±1%). Charge current in the constant voltage
mode drops as the battery cell under charge reaches its maximum capacity.
End of Charge Cycle Termination and Recharge
Sequence
When the charge current drops to 7.5% of the programmed fast charge current level in the constant
voltage mode, the device terminates charging and
goes into a sleep state. The charger will remain in
a sleep state until the battery voltage decreases to
a level below the battery recharge voltage threshold (VRCH).
When the input supply is disconnected, the charger will automatically transition into a power-saving
sleep mode. Only consuming an ultra-low 0.3μA in
sleep mode, the AAT3697 minimizes battery drain
when it is not charging. This feature is particularly
useful in applications where the input supply level
may fall below the battery charge or under-voltage
lockout level. In such cases where the AAT3697
input voltage drops, the device will enter sleep
mode and automatically resume charging once the
input supply has recovered from the fault condition.
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
System Operation Flow Chart
Yes
Yes
ADP
No
No
Enable
No
Timing
Yes
Yes
Expire
No
Yes
No
Yes
Set
No
No
Yes
BAT_EOC
No
Yes
TERM
No
Application Information
Adapter Power Input
Constant current charge levels up to 2.0A may be
programmed by the user when powered from a sufficient input power source. The AAT3697 will operate from the adapter input over a 4.0V to 5.5V
range.
3697.2007.02.1.1
The constant current fast charge current for the
adapter input is set by the RSET resistor connected
between the ADPSET pin and ground. Refer to
Table 1 for recommended RSET values for a desired
constant current charge level. The presence of voltage on the adapter input is indicated by the ADPP#
pin function. This indicator pin uses an internal open
drain device that will pull the ADPP# pin low when
voltage is detected on the ADP pin. The precise
11
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Thermal Loop Control
Due to the integrated nature of the linear charging
control pass device for the adapter input, a special
thermal loop control system has been employed to
maximize charging current under all operating conditions. The thermal management system measures the internal circuit die temperature and reduces
the fast charge current when the device exceeds a
preset internal temperature control threshold. Once
the thermal loop control becomes active, the fast
charge current is initially reduced by a factor of 0.44.
The initial thermal loop current can be estimated by
the following equation:
Eq. 1:
ITLOOP = ICH · 0.44
The thermal loop control re-evaluates the circuit die
temperature in 330ms intervals and adjusts the fast
charge current back up in small steps to the full fast
charge current level or until an equilibrium current
is discovered and maximized for the given ambient
temperature condition. The thermal loop controls
the system charge level; therefore, the AAT3697
will always provide the highest level of constant
current in the fast charge mode possible for any
given ambient temperature condition.
Adapter Input Charge Inhibit and Resume
The AAT3697 has a UVLO and power on reset feature so that the charger will suspend charging and
shut down if the input supply to the adapter pin
drops below the UVLO threshold. When power is
re-applied to the adapter pin or the UVLO conditions recovers, the system charge control will
assess the state of charge on the battery cell and
will automatically resume charging in the appropriate mode for the condition of the battery.
Enable / Disable
The AAT3697 provides an enable function to control
the charger IC on and off. The enable (EN) pin is
active high. When pulled to a logic low level, the
AAT3697 will be shut down and forced into the sleep
12
state. Charging will be halted regardless of the battery voltage or charging state. When the device is reenabled, the charge control circuit will automatically
reset and resume charging functions with the appropriate charging mode based on the battery charge
state and measured cell voltage on the BAT pin.
Programming Charge Current
The fast charge constant current charge level is
user programmed with a set resistor placed
between the ADPSET pin and ground. The accuracy of the fast charge, as well as the preconditioning trickle charge current, is dominated by the
tolerance of the set resistor used. For this reason,
a 1% tolerance metal film resistor is recommended
for the set resistor function.
Fast charge constant current levels from 50mA to
2.0A can be set by selecting the appropriate resistor value from Table 1.
ICH (mA)
Ω)
RSET (kΩ
ICH (mA)
Ω)
RSET (kΩ
100
200
300
400
500
600
700
800
900
1000
84.5
43.2
28.0
21.0
16.9
13.3
11.5
10.2
90.9
8.06
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
7.32
6.65
6.04
5.62
5.36
4.87
4.53
4.22
3.92
3.65
Table 1: Recommended RSET Values.
10000
ICH (mA)
charging function of the AAT3697 may be read from
the DATA pin and/or status LEDs. Please refer to
the Battery Charge Status Indication discussion for
further details on data reporting.
1000
100
1
10
100
RSET (kΩ
Ω)
Figure 2: ICH vs. RSET.
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Protection Circuitry
Programmable Watchdog Timer
The AAT3697 contains a watchdog timing circuit to
shut down charging functions in the event of a defective battery cell not accepting a charge over a preset
period of time. Typically, a 0.1μF ceramic capacitor
is connected between the CT pin and ground. When
a 0.1μF ceramic capacitor is used, the device will
time out a shutdown condition if the trickle charge
mode exceeds 25 minutes and a combined trickle
charge plus fast charge mode of 3 hours. When the
device transitions to the constant voltage mode, the
timing counter is reset and will time out after an additional 3 hours if the charge current does not drop to
the charge termination level.
Mode
Trickle Charge (TC) Time Out
Trickle Charge (TC) +
Fast Charge (CC) Time Out
Constant Voltage (VC) Mode
Time Out
Time
25 minutes
3 hours
3 hours
Table 2: Summary for a 0.1μF Ceramic
Capacitor Used for the Timing Capacitor.
The CT pin is driven by a constant current source
and will provide a linear response to increases in the
timing capacitor value. Thus, if the timing capacitor
were to be doubled from the nominal 0.1μF value,
the time-out periods would be doubled.
If the programmable watchdog timer function is not
needed, it can be disabled by terminating the CT
pin to ground. The CT pin should not be left floating or un-terminated, as this will cause errors in the
internal timing control circuit.
The constant current provided to charge the timing
capacitor is very small, and this pin is susceptible
to noise and changes in capacitance value.
Therefore, the timing capacitor should be physically located on the printed circuit board layout as
close as possible to the CT pin. Since the accuracy of the internal timer is dominated by the capacitance value, a 10% tolerance or better ceramic
capacitor is recommended. Ceramic capacitor
materials, such as X7R and X5R types, are a good
choice for this application.
3697.2007.02.1.1
Over-Voltage Protection
An over-voltage event is defined as a condition
where the voltage on the BAT pin exceeds the
maximum battery charge voltage and is set by the
over-voltage protection threshold (VOVP). If an
over-voltage condition occurs, the AAT3697 charge
control will shut down the device until the voltage
on the BAT pin drops below VOVP. The AAT3697
will resume normal charging operation after the
over-voltage condition is removed. During an overvoltage event, the STAT LEDs will report a system
fault, and the actual fault condition can be read via
the DATA pin signal.
Over-Temperature Shutdown
The AAT3697 has a thermal protection control circuit which will shut down charging functions should
the internal die temperature exceed the preset
thermal limit threshold.
Battery Temperature Fault Monitoring
In the event of a battery over-temperature condition, the charge control will turn off the internal pass
device and report a battery temperature fault on the
DATA pin function. The STAT LEDs will also display a system fault. After the system recovers from
a temperature fault, the device will resume charging operation.
The AAT3697 checks battery temperature before
starting the charge cycle, as well as during all
stages of charging. This is accomplished by monitoring the voltage at the TS pin. Either a negative
temperature coefficient thermistor (NTC) or positive temperature coefficient thermistor (PTC) can
be used because the AAT3697 checks to see that
the voltage at TS is within a voltage window bounded by VTS1 and VTS2. Please see the equations
below for specifying resistors:
RT1 and RT2 for use with NTC Thermistor
Eq. 2: RT1 =
RT2 =
5 ⋅ RTH ⋅ RTC
3 ⋅ (RTC - RTH)
5 ⋅ RTH ⋅ RTC
(2 ⋅ RTC) - (7 ⋅ RTH)
13
AAT3697
2A Lithium-Ion/Polymer Battery Charger
RT1 and RT2 for use with PTC Thermistor
Eq. 3: RT1 =
RT2 =
5 ⋅ RTH ⋅ RTC
3 ⋅ (RTH - RTC)
5 ⋅ RTH ⋅ RTC
(2 ⋅ RTH) - (7 ⋅ RTC)
Where RTC is the thermistor's cold temperature
resistance and RTH is the thermistor's hot temperature resistance. See thermistor specifications for
information. To ensure there is no dependence on
the input supply changes, connect the divider
between VADP and GND. Disabling the temperature-monitoring function is achieved by applying a
voltage between VTS1 and VTS2 on the TS pin.
Battery Charge Status Indication
The AAT3697 indicates the status of the battery
under charge with two different systems. First, the
device has two status LED driver outputs. These
two LEDs can indicate simple functions such as no
battery charge activity, battery charging, charge
complete, and charge fault. The AAT3697 also
provides a bi-directional data reporting function so
that a system microcontroller can interrogate the
DATA pin and read any one of 12 system states.
Status Indicator Display
Simple system charging status states can be displayed using one or two LEDs in conjunction with
the STAT1 and STAT2 pins on the AAT3697.
These two pins are simple open drain switches
used to connect the LED cathodes to ground. It is
not necessary to use both display LEDs if a user
simply wants to have a single lamp to show "charging" or "not charging."
This can be accomplished by using the STAT1 pin
and a single LED. Using two LEDs and both STAT
pins simply gives the user more information to the
charging states. Refer to Table 3 for LED display
definitions. The LED anodes should be connected
to VADP.
The LEDs should be biased with as little current as
necessary to create reasonable illumination; therefore, a ballast resistor should be placed between
the LED cathodes and the STAT1/2 pins. LED current consumption will add to the overall thermal
power budget for the device package, hence it is
good to keep the LED drive current to a minimum.
2mA should be sufficient to drive most low-cost
green or red LEDs. It is not recommended to
exceed 8mA for driving an individual status LED.
The required ballast resistor values can be estimated using the following formulas:
Eq. 4: RB(STAT1/2) =
(VADP - VF(LED))
ILED(STAT1/2)
Example:
Eq. 5: RB(STAT1) =
(5.5V - 2.0V)
= 1.75kΩ
2mA
Note: Red LED forward voltage (VF) is typically
2.0V @ 2mA
Event Description
Charge Disabled or Low Supply
Charge Enabled Without Battery
Battery Charging
Charge Completed
Fault
STAT1
STAT2
Off
Flash1
On
Off
On
Off
Flash1
Off
On
On
Table 3: LED Status Indicator.
1. Flashing rate depends on output capacitance.
14
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Digital Charge Status Reporting
output, and to maintain the integrity of the data timing for the system, the pull-up resistor on the data
line should be low enough in value so that the
DATA signal returns to the high state without delay.
If the pull-up resistor is too high, the strobe pulse
from the system microcontroller could exceed the
maximum pulse time and the DATA output control
could issue false status reports. A 1.5kΩ resistor is
recommended when pulling the DATA pin high to
5.0V on the VADP input. If the data line is pulled
high to a voltage level less than 5.0V, the pull-up
resistor can be calculated based on a recommended minimum pull-up current of 3mA. Use the following formula:
The AAT3697 has a comprehensive digital data
reporting system by use of the DATA pin feature.
This function can provide detailed information
regarding the status of the charging system. The
DATA pin is a bi-directional port which will read
back a series of data pulses when the system
microcontroller asserts a request pulse. This single strobe request protocol will invoke one of 12
possible return pulse counts that the system microcontroller can look up based on the serial report
data listed in Table 4.
The DATA pin function logic is active low and
should normally be pulled high to VADP. This data
line can also be pulled high to the same level as the
high state for the logic I/O port on the system
microcontroller. In order for the DATA pin control
circuit to generate clean, sharp edges for the data
Eq. 6: RPULL-UP ≤
VPULL-UP
3mA
1.8V to 5.0V
IN
AAT3697
Status
Control
RPULL_UP
IN
DATA Pin
GPIO
OUT
OUT
μP GPIO
Port
Figure 3: Data Pin Application Circuit.
Data Timing
The system microcontroller should assert an active
low data request pulse for minimum duration of
200ns; this is specified by TLO(DATA). Upon sensing
the rising edge of the end of the data request pulse,
3697.2007.02.1.1
the AAT3697 status data control will reply the data
word back to the system microcontroller after a
delay specified by the data report time specification
TDATA(RPT). The period of the following group of
data pulses will be specified by TDATA.
15
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Timing Diagram
SQ
SQPULSE
PDATA
System Reset
System Start
CK
TSYNC
Data
TLAT
TDATA(RPT) = TSYNC + TLAT < 2.5 PDATA
TOFF > 2 PDATA
TOFF
N=1
N=2
N=3
N
DATA Report Status
1
Chip Over-Temperature Shutdown.
2
Battery Temperature Fault.
3
Over-Voltage Turn Off.
4
Not Used.
5
ADP Watchdog Time-Out in Battery Condition Mode.
6
ADP Battery Condition Mode.
7
ADP Watchdog Time-Out in Constant Current Mode.
8
ADP Thermal Loop Regulation in Constant Current Mode.
9
ADP Constant Current Mode.
10
ADP Watchdog Time-Out in Constant Voltage Mode.
11
ADP Constant Voltage Mode.
12
ADP End of Charging.
23
Data Report Error.
Table 4: Serial Data Report Table.
16
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Thermal Considerations
Where:
The AAT3697 is offered in a 3x3mm TDFN package which can provide up to 2.0W of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance
of 50°C/W. Many considerations should be taken
into account when designing the printed circuit
board layout, as well as the placement of the
charger IC package in proximity to other heat generating devices in a given application design. The
ambient temperature around the charger IC will
also have an effect on the thermal limits of a battery charging application. The maximum limits that
can be expected for a given ambient condition can
be estimated by the following discussion.
TA = Ambient Temperature in °C
First, the maximum power dissipation for a given
situation should be calculated:
TJ = Maximum Device Junction Temperature
Below the Thermal Loop Threshold
PD = Total Power Dissipation by the Device
θJA = Package Thermal Resistance in °C/W
Example:
For an application where the fast charge current for
the adapter mode is set to 1A, VADP = 5.0V and the
battery voltage at 3.6V, what is the maximum ambient temperature at which the thermal loop will
become active?
Given:
VADP = 5.0V
VBAT = 3.6V
Eq. 7: PD = [(VIN - VBAT) · ICC + (VIN · IOP)]
Where:
PD
= Total Power Dissipation by the Device
VIN = Input Voltage Amplitude, VADP
VBAT = Battery Voltage as Seen at the BAT Pin
ICC
= Maximum Constant Fast Charge Current
Programmed for the Application
IOP
= Quiescent Current Consumed by the
Charger IC for Normal Operation
Next, the maximum operating ambient temperature
for a given application can be estimated based on
the thermal resistance of the 3x3mm TDFN package when sufficiently mounted to a PCB layout and
the internal thermal loop temperature threshold.
ICC
= 1A
IOP
= 0.75mA
TJ
= 110°C
θJA = 50°C/W
Using Equation 7, calculate the device power dissipation for the stated condition:
Eq. 9: PD = (5.0V - 3.6V)(1A) + (5.0V · 0.75mA)
= 1.40375W
The maximum ambient temperature before the
AAT3697 thermal loop becomes active can now be
calculated using Equation 8:
Eq. 10: TA = 110°C - (50°C/W · 1.40375W)
Eq. 8: TA = TJ - (θJA · PD)
= 39.8125°C
Therefore, under the stated conditions for this
worst case power dissipation example, the
AAT3697 will enter the thermal loop and lower the
fast charge constant current when the ambient
operating temperature rises above 39.8°C.
3697.2007.02.1.1
17
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Capacitor Selection
Input Capacitor
In general, it is good design practice to place a
decoupling capacitor between the ADP pin and
ground. An input capacitor in the range of 1μF to
22μF is recommended. If the source supply is
unregulated, it may be necessary to increase the
capacitance to keep the input voltage above the
under-voltage lockout threshold during device
enable and when battery charging is initiated.
If the AAT3697 adapter input is to be used in a system with an external power supply source, such as
a typical AC-to-DC wall adapter, then a CIN capacitor in the range of 10μF should be used. A larger
input capacitor in this application will minimize
switching or power transient effects when the
power supply is "hot plugged" in.
Output Capacitor
The AAT3697 only requires a 1μF ceramic capacitor on the BAT pin to maintain circuit stability. This
value should be increased to 10μF or more if the
battery connection is made any distance from the
charger output. If the AAT3697 is to be used in
applications where the battery can be removed
from the charger, such as with desktop charging
cradles, an output capacitor greater than 10μF may
be required to prevent the device from cycling on
and off when no battery is present.
Printed Circuit Board Layout
Considerations
For the best results, it is recommended to physically place the battery pack as close as possible to
the AAT3697 BAT pin. To minimize voltage drops
on the PCB, keep the high current carrying traces
adequately wide. For maximum power dissipation
of the AAT3697 3x3mm TDFN package, the metal
substrate should be solder bonded to the board. It
is also recommended to maximize the substrate
contact to the PCB ground plane layer to further
increase local heat dissipation. Refer to the
AAT3697 evaluation board for a good layout example (see Figures 4 and 5).
AAT3697 Evaluation Board Layout
Figure 4: AAT3697 Evaluation Board
Component Side Layout.
18
Figure 5: AAT3697 Evaluation Board
Solder Side Layout.
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
AAT3697 Evaluation Board Schematic Diagram
ADP
GND
1
2
C1
10μF
RED
LED D3
J1
ON/OFF
1 2 3
R3
1.5K
U1
R1
10k
BAT
TS
GND
RED
LED D1
R4
1.5K
R5
1.5K
R7
1.5K
(TDFN33-12)
4
EN
2
ADP
1
1
3
2
GRN
LED D2
BAT
ADPP#
5
STAT2
8
STAT1
9
DATA
7
DATA
AAT3697
ADPSET
C2
10μF
6
TS
SW1
GND
R2
10k
12
3
CT
R6
8.06K
10
C3
0.1μF
CT
3697.2007.02.1.1
19
AAT3697
2A Lithium-Ion/Polymer Battery Charger
AAT3697 Evaluation Board Bill of Materials (BOM)
Quantity Description
1
1
2
Test Pin
Connecting Terminal Block,
2.54mm, 2 Position
Connecting Terminal Block,
2.54mm, 3 Position
Capacitor, Ceramic, 10μF
6.3V 10% X5R 0805
Capacitor, Ceramic, 0.1μF
10% 16V X7R 0603
Typical Red LED, Ultra-Bright
1
Typical Green LED
1
1
Header, 3-Pin
Resistor, 10kΩ, 1/16W
1% 0603 SMD
Resistor, 8.06kΩ, 1/16W
1% 0603 SMD
Resistor, 1.5kΩ, 1/16W
5% 0603 SMD
Switch Tact 6mm SPST
H = 5.0mm
AAT3697 2A Lithium-Ion/
Polymer Battery Charger
1
2
1
1
4
1
1
20
Desig.
Footprint
Manufacturer
Part Number
DATA
ADP, GND
PAD
TBLOK2
Mill-Max
Phoenix Contact
6821-0-0001-00-00-08-0
277-1274-ND
BAT,
GND, TS
C1, C2
TBLOK3
Phoenix Contact
277-1273-ND
0805
Murata
GRM219R60J106KE19
C3
0603
Murata
GRM188R71C104KA01D
D1, D3
1206LED
D2
J1
R1, R2
Chicago Miniature
Lamp
1206LED
Chicago Miniature
Lamp
HEADER2MM-3 Sullins
0603
Panasonic/ECG
CMD15-21SRC/TR8
CMD15-21VGC/TR8
6821-0-0001-00-00-08-0
P10KCFCT-ND
R6
0603
Panasonic/ECG
P8.06KHCT-ND
R3, R4,
R5, R7
SW1
0603
Panasonic/ECG
P1.5KCGCT-ND
Switch
CKN9012-ND
U1
TDFN33-12
ITT Industries/
C&K Div
AnalogicTech
AAT3697IWP-4.2
3697.2007.02.1.1
AAT3697
2A Lithium-Ion/Polymer Battery Charger
Ordering Information
Trickle Charge
Package
Marking1
Part Number (Tape and Reel)2
Yes
TDFN33-12
VCXYY
AAT3697IWP-4.2-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
Package Information3
TDFN33-12
Index Area
0.43 ± 0.05
Detail "A"
0.45 ± 0.05
2.40 ± 0.05
3.00 ± 0.05
0.1 REF
C0.3
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
0.23 ± 0.05
Pin 1 Indicator
(optional)
0.05 ± 0.05
0.23 ± 0.05
0.75 ± 0.05
Detail "A"
Side View
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the
lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required
to ensure a proper bottom solder connection.
3697.2007.02.1.1
21
AAT3697
2A Lithium-Ion/Polymer Battery Charger
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights,
or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice.
Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech
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AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
22
3697.2007.02.1.1