201890B.pdf

DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
General Description
Features
The AAT3687 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 AAT3687 precisely
regulates battery charge voltage and current for 4.2V
lithium-ion/polymer battery cells. Adapter charge current
rates can be programmed up to 1.5A. 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.
•
•
•
•
Input Voltage Range: 4.0V to 5.5V
Up to 1.5A 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 Over-Temperature
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 AAT3687 is available in a Pb-free, thermally-enhanced,
space-saving 12-pin TDFN 3x3mm package and is rated
over the -40°C to +85°C temperature range.
•
•
•
•
•
•
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#
Enable
EN
BAT
COUT
10μF
DATA
Serial Interface
TS
+
BATT-
AAT3687
CT
Adapter
ADP
ADPSET
CIN
10μF
STAT1
GND
CT
0.1μF
TEMP
STAT2
RSET
RB1
RB2
Battery
Pack
LED1
LED2
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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1
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Pin Descriptions
Pin #
Name
Type
1
2
3
BAT
ADP
GND
Out
In
Ground
4
EN
In
5
6
7
8
9
ADPP#
TS
DATA
STAT2
STAT1
Out
In/Out
Out
Out
Out
10
CT
In/Out
11
12
EP
N/C
ADPSET
In/Out
Function
Battery charging and sensing.
Adapter input.
Ground connection.
AAT3687: Enable pin. Logic high enables the IC.
AAT3687-2: Enable pin. Logic high enables the IC. EN tied to internal 4M pull-up resistor to ADP.
Adapter present indicator. This pin is open drain until ADP pin reaches threshold.
Connect to 10k NTC thermistor.
Status report to microcontroller via serial interface: open drain.
Battery charge status indicator pin to drive an LED: active low, open drain.
Battery charge status indicator pin to drive an LED: active low, open drain.
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.
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)
2
BAT
1
12
ADPSET
ADP
2
11
N/C
GND
3
10
CT
EN
4
9
STAT1
ADPP#
5
8
STAT2
TS
6
7
DATA
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201890B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 26, 2012
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
AAT3687 Feature Options
Product
Trickle Charge
Internal Pull-Up
Resistor on EN Pin
Can Leave
TS Pin Open
AAT3687
AAT3687-1
Yes
Yes
No
Yes
No
Yes
Absolute Maximum Ratings1
Symbol
VP
VP
VN
TJ
TLEAD
Description
Value
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)
-0.3 to 7.0
-0.3 to 6.0
-0.3 to VP + 0.3
-40 to 150
300
Units
V
°C
Thermal Information
Symbol
JA
PD
Description
Maximum Thermal Resistance
Maximum Power Dissipation
2
Value
Units
50
2.0
°C/W
W
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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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3
DATA SHEET
AAT3687
Li-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
Operation
ADP
Adapter Voltage Range
VADPP
Adapter Present Threshold Voltage
Under-Voltage Lockout (UVLO)
VUVLO
UVLO Hysteresis
Operating Current
IOP
ISLEEP
Sleep Mode Current
ILeakage
Reverse Leakage Current from BAT Pin
Voltage Regulation
End of Charge Voltage Accuracy
VBAT_EOC1
VCH/VCH
Output Charge Voltage Tolerance
VMIN
Preconditioning Voltage Threshold
VRCH
Conditions
Min
4.0
3.0
3.0
150
0.75
0.3
1
1.0
Rising Edge
Charge Current = 100mA
AAT3687: VBAT = 4.25V
AAT3687-1: VBAT = 4.25V
VBAT = 4V, ADP Pin Open
4.158
2.8
4.20
0.5
3.0
Max
Units
5.5
V
V
V
mV
mA
1.5
1.0
3
100
4.242
3.15
VIN = 5.5V
0.2
0.25
V
%
V
V
1500
mA
%
V
0.35

10
2.0
4000
CC Mode
μA
μA
VBAT_EOC 0.1
Battery Recharge Voltage Threshold
Current Regulation
ICH
Charge Current
ICH/ICH
Charge Current Regulation Tolerance
VADPSET
ADPSET Pin Voltage
KIA
Current Set Factor: ICH/IADPSET
Charging Devices
Adapter Charging Transistor
RDS(ON)
On Resistance
Typ
1. The AAT3687 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
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201890B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 26, 2012
DATA SHEET
AAT3687
Li-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
IEN(H)
EN Input Current
VADPP#
Output Low Voltage
Preconditioning Plus Constant Current
TC
Mode Time Out
Preconditioning Time Out
TP
TV
Constant Voltage Mode Time Out
VSTAT
Output Low Voltage
ISTAT
STAT Pin Current Sink Capability
VOVP
Over-Voltage Protection Threshold
ITK/ICHG
Pre-Charge Current
ITERM/ICHG
Charge Termination Threshold Current
ITS
Current Source from TS Pin
TS1
TS Hot Temperature Fault
TS2
TS Cold Temperature Fault
IDATA
IADPP#
VDATA(H)
VDATA(L)
SQPULSE
tPERIOD
fDATA
TREG
TLOOP_IN
TLOOP_OUT
TOVSD
DATA Pin Sink Current
ADPP# Current Sink
Input High Threshold
Input Low Threshold
Status Request Pulse Width
System Clock Period
Data Output Frequency
Thermal Loop Regulation
Thermal Loop Entering Threshold
Thermal Loop Exiting Threshold
Over-Temperature Shutdown Threshold
Conditions
Min
Typ
Max
Units
0.4
10
0.4
V
V
μA
V
1.6
AAT3687-1 Only; VEN = 5V
ADPP# Pin Sinks 500μA
CT = 0.1μF, VADP = 5.5V
3.0
Hours
CT = 0.1μF, VADP = 5.5V
CT = 0.1μF, VADP = 5.5V
STAT Pin Sinks 4mA
25
3.0
Minutes
Hours
V
mA
V
%
%
μA
Threshold
Hysteresis
Threshold
Hysteresis
DATA Pin is Active Low State
ADPP# Pin is Active Low State
0.4
70
310
2.2
8.0
4.4
10
7.5
80
330
15
2.3
10
90
350
2.4
3
8
1.6
0.4
Status Request
200
50
20
90
110
85
145
mV
V
mV
mA
mA
V
V
ns
μs
kHz
°C
°C
°C
°C
1. The AAT3687 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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201890B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 26, 2012
5
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Typical Characteristics
Charge Current vs. RSET
Battery Voltage vs. Supply Voltage
4.242
10000
VBAT (V)
ICH (mA)
4.221
1000
4.200
100
4.179
4.158
10
1
10
4.5
100
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
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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100
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Typical Characteristics
Charge Current vs. Battery Voltage
Fast 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
0.2
600
VBAT = 3.9V
VBAT = 3.5V
400
200
0.0
0
2.5
2.9
3.3
3.7
4.1
4.5
4.0
4.5
Battery Voltage (V)
5.5
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
0.70
8
Counter Timeout (%)
0.80
IOP (mA)
0.60
0.50
Constant Current
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)
1000
-10
-50
-25
0
25
50
75
100
Temperature (°°C)
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DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Typical Characteristics
CT Pin Capacitance vs. Counter Timeout
Temperature Sense Output Current
vs. Temperature
2.0
88
TS Pin Current (μA)
Capacitance (μ
μF)
1.8
1.6
1.4
Precondition Timeout
1.2
1.0
0.8
Precondition + Constant Current Timeout
or Constant Voltage Timeout
0.6
0.4
0.2
84
82
80
78
76
74
72
0.0
0
2
4
6
Time (hours)
8
86
8
10
-50
-25
0
25
50
75
Temperature (°°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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100
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Functional Block Diagram
CV/
Precharge1
Constant
Current
Charge
Control
4.2V
BAT
OverTemperature
Protection
Current
Compare
ADPSET
UVLO
ADP
ADPP#
Voltage
Sense
Reverse Blocking
80μA
STAT1
STAT2
DATA
TS
Charge
Status
Serial
Data
Window
Comparator
IC enable
Watchdog
Timer
CT
EN
GND
Functional Description
The AAT3687 is a highly integrated single-cell lithiumion/polymer battery charger IC designed to operate with
standard AC adapter input sources, while requiring a
minimum number of external components. The AAT3687
precisely regulates battery charge voltage and current
for 4.2V lithium-ion/polymer battery cells.
The adapter charge input constant current level can be
programmed up to 1.5A for rapid charging applications.
The AAT3687 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 level. This intelligent ther-
mal management system permits the AAT3687 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 AAT3687
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.
1. Precharge applies to AAT3687 and AAT3687-1 only.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201890B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 26, 2012
9
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
Charge Complete Voltage
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 AAT3687 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 AAT3687 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
AAT3687 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 AAT3687 begins the
10
constant current fast charging phase. The fast charge
constant current (ICC) amplitude is programmed by the
user via the RSET resistor. The AAT3687 remains in the
constant current charge mode until the battery reaches
the voltage regulation point, VBAT.
Constant Voltage Charging
The system transitions to a constant voltage charging
mode when the battery voltage reaches the output
charge regulation threshold (VBAT) 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 (1μA
for AAT3687-1), the AAT3687 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 AAT3687 input voltage drops,
the device will enter sleep mode and automatically
resume charging once the input supply has recovered
from the fault condition.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201890B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 26, 2012
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
System Operation Flow Chart
Yes
Yes
No
No
Enable
No
Timing
Yes
Yes
Expire
No
Yes
No
Yes
(AAT3687)
Yes
Set
No
No
Yes
BAT_EOC
No
Yes
TERM
No
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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11
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Application Information
Adapter Power Input
Constant current charge levels up to 1.5A may be programmed by the user when powered from a sufficient
input power source. The AAT3687 will operate from the
adapter input over a 4.0V to 5.5V range.
The constant current fast charge current for the adapter
input is set by the RSET resistor connected between the
ADPSET 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 charging function of the AAT3687 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.
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 = ICC · 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 AAT3687 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 AAT3687 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 AAT3687 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 AAT3687 will be
shut down and forced into the sleep state. Charging will
be halted regardless of the battery voltage or charging
state. When the device is re-enabled, 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 1.5A
can be set by selecting the appropriate resistor value
from Table 1.
ICC
ADP
RSET (k)
50
75
100
200
300
400
500
600
700
N/A
N/A
84.5
43.2
28.0
21.0
16.9
13.3
11.5
ICC
ADP
RSET (k)
800
900
1000
1100
1200
1300
1400
1500
10.2
9.09
8.06
7.32
6.65
6.04
5.62
5.36
Table 1: Recommended RSET Values.
12
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201890B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 26, 2012
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
ICH (mA)
10000
1000
100
10
1
10
100
RSET (kΩ
Ω)
Figure 2: IFASTCHARGE vs. RSET.
Protection Circuitry
Programmable Watchdog Timer
The AAT3687 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
Time
Trickle Charge (TC) Time Out
Trickle Charge (TC) + Fast
Charge (CC) Time Out
Constant Voltage (VC) Mode
Time Out
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 unterminated, 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.
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 AAT3687 charge control will shut down the
device until the voltage on the BAT pin drops below VOVP.
The AAT3687 will resume normal charging operation
after the over-voltage condition is removed. During an
over-voltage 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 AAT3687 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 AAT3687 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. This system is intended for use with negative temperature coefficient thermistors (NTC) which are typically
integrated into the battery package. Most of the commonly used NTC thermistors in battery packs are approximately 10k at room temperature (25°C). The TS pin
has been specifically designed to source 80μA of current
to the thermistor. The voltage on the TS pin resulting
from the resistive load should stay within a window of
335mV to 2.32V. If the battery becomes too hot during
charging due to an internal fault or excessive fast charge
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13
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
current, the thermistor will heat up and reduce in value,
pulling the TS pin voltage lower than the TS1 threshold,
and the AAT3687 will signal the fault condition.
If the use of the TS pin function is not required by the
system, it should be terminated to ground using a 10k
resistor. Alternatively, on the AAT3687-1 and AAT36872, the TS pin may be left open.
Example:
Eq. 3: RB(STAT1) =
Note: Red LED forward voltage (VF) is typically 2.0V @
2mA
Battery Charge Status Indication
The AAT3687 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
AAT3687 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 AAT3687. 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. 2: RB(STAT1/2) =
(5.5V - 2.0V)
= 1.75kΩ
2mA
Event Description
STAT1
STAT2
Charge Disabled or Low Supply
Charge Enabled Without Battery
Battery Charging
Charge Completed
Fault
Off
Flash1
On
Off
On
Off
Flash1
Off
On
On
Table 3: LED Status Indicator.
Digital Charge Status Reporting
The AAT3687 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.
N
DATA Report Status
1
2
3
4
5
6
7
8
9
10
11
12
23
Chip Over-Temperature Shutdown.
Battery Temperature Fault.
Over-Voltage Turn Off.
Not Used.
ADP Watchdog Time-Out in Battery Condition Mode.
ADP Battery Condition Mode.
ADP Watchdog Time-Out in Constant Current Mode.
ADP Thermal Loop Regulation in Constant Current Mode.
ADP Constant Current Mode.
ADP Watchdog Time-Out in Constant Voltage Mode.
ADP Constant Voltage Mode.
ADP End of Charging.
Data Report Error.
Table 4: Serial Data Report Table.
(VADP - VF(LED))
ILED(STAT1/2)
1. Flashing rate depends on output capacitance.
14
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DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
1.8V to 5.0V
IN
RPULL_UP
AAT3687
Status
Control
IN
DATA Pin
GPIO
OUT
OUT
μP GPIO
Port
Figure 3: Data Pin Application Circuit.
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 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 1.5k 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 recom-
mended minimum pull-up current of 3mA. Use the following formula:
Eq. 4: RPULL-UP ≤
VPULL-UP
3mA
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, the AAT3687 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.
Timing Diagram
SQPULSE
SQ
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
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15
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Thermal Considerations
Given:
The AAT3687 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.
VADP
VBAT
ICC
IOP
TJ
JA
First, the maximum power dissipation for a given situation should be calculated:
=
=
=
=
=
=
5.0V
3.6V
1A
0.75mA
110°C
50°C/W
Using Equation 5, calculate the device power dissipation
for the stated condition:
Eq. 7: PD = (5.0V - 3.6V)(1A) + (5.0V · 0.75mA)
= 1.40375W
The maximum ambient temperature before the AAT3687
thermal loop becomes active can now be calculated
using Equation 6:
Eq. 5: PD = [(VIN - VBAT) · ICC + (VIN · IOP)]
Eq. 8: TA = 110°C - (50°C/W · 1.40375W)
Where:
PD
VIN
VBAT
ICC
IOP
=
=
=
=
Total Power Dissipation by the Device
Input Voltage Amplitude, VADP
Battery Voltage as Seen at the BAT Pin
Maximum Constant Fast Charge Current
Programmed for the Application
= 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.
Eq. 6: TA = TJ - (θJA · PD)
Where:
TA = Ambient Temperature in °C
TJ = Maximum Device Junction Temperature Below the
Thermal Loop Threshold
PD = Total Power Dissipation by the Device
JA = 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?
16
= 39.8125°C
Therefore, under the stated conditions for this worst
case power dissipation example, the AAT3687 will enter
the thermal loop and lower the fast charge constant current when the ambient operating temperature rises
above 39.8°C.
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 AAT3687 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.
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DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Output Capacitor
The AAT3687 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
AAT3687 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
AAT3687 BAT pin. To minimize voltage drops on the PCB,
keep the high current carrying traces adequately wide.
For maximum power dissipation of the AAT3687 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
AAT3687 evaluation board for a good layout example
(see Figures 4 and 5).
AAT3687 Evaluation Board Layout
Figure 4: AAT3687 Evaluation Board
Component Side Layout.
Figure 5: AAT3687 Evaluation Board
Solder Side Layout.
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17
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
AAT3687 Evaluation Board Schematic Diagram
TermB2
1
ADP
2
GNDTermB2
C1
10μF
J1
ON/OFF
RED
GRN
RED
LED D3 LED D2 LED D1
1 2 3
R3
1.5kΩ
R1
Open
2
TermB3
BAT
TS
GND
1
1
3
2
R5
1.5kΩ
R7
1.5kΩ
(TDFN33-12)
U1
4
R4
1.5kΩ
ADPP#
EN
ADP
BAT
STAT2
STAT1
DATA
5
8
9
7
DATA
AAT3687
6
TS
ADPSET
12
C2
10μF
GND
R2
10kΩ
3
CT
R6
8.06kΩ
10
SW1
C3
0.1μF
CT
AAT3687 Evaluation Board Bill of Materials (BOM)
Quantity
Description
Desig.
Footprint
Manufacturer
Part Number
1
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
Typical Green LED
Header, 3-Pin
Resistor, 10k, 1/16W 5%
0603 SMD
Resistor, 8.06k, 1/16W 1%
0603 SMD
Resistor, 1.5k, 1/16W 5%
0603 SMD
Switch Tact 6mm SPST
H = 5.0mm
AAT3687 Lithium-Ion/Polymer
Battery Charger
DATA
PAD
Mill-Max
6821-0-0001-00-00-08-0
ADP, GND
TBLOK2
Phoenix Contact
277-1274-ND
BAT,
GND, TS
TBLOK3
Phoenix Contact
277-1273-ND
C1, C2
0805
Murata
GRM219R60J106KE19
C3
0603
Murata
GRM188R71C104KA01D
D1, D3
D2
J1
1206LED
1206LED
HEADER2MM-3
Chicago Miniature Lamp
Chicago Miniature Lamp
Sullins
CMD15-21SRC/TR8
CMD15-21VGC/TR8
6821-0-0001-00-00-08-0
R2
0603
Panasonic/ECG
P10KCFCT-ND
R6
0603
Panasonic/ECG
P8.06KHCT-ND
R3, R4,
R5, R7
0603
Panasonic/ECG
P1.5KCGCT-ND
SW1
Switch
ITT Industries/
C&K Div
CKN9012-ND
U1
TDFN33-12
Skyworks
AAT3687IWP-4.2
1
1
2
1
2
1
1
1
1
4
1
1
18
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DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Ordering Information
Trickle Charge
Package
Marking1
Part Number (Tape and Reel)2
Yes
Yes
TDFN33-12
TDFN33-12
PIXYY
TQXYY
AAT3687IWP-4.2-T1
AAT3687IWP-4.2-1-T1
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
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.
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19
DATA SHEET
AAT3687
Li-Ion/Polymer Battery Charger
Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
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service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
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Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product
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Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
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20
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