RT9503A
Fully Integrated Linear Single Cell Li-Ion Battery Charger
with Power Path
General Description
The RT9503A is a fully integrated low cost single-cell Li-
Ion battery charger IC ideal for portable applications. The
RT9503A is capable of being powered up via the AC adapter
and USB (Universal Serial Bus) port inputs. The RT9503A
can automatically detect and select the AC adapter and
the USB port as the power source for the charger. The
RT9503A enters sleep mode when both supplies are
removed.
The RT9503A optimizes the charging task by using a
control algorithm including preconditioning mode, fast
charge mode, and constant voltage mode. The charging
task is terminated as the charge current drops below the
preset threshold. The USB charge current can be selected
from preset ratings of 100mA and 500mA, while the AC
adapter charge current can be programmed up to 1A with
an external resistor. The internal thermal feedback circuitry
regulates the die temperature to optimize the charge rate
for all ambient temperatures.
The RT9503A features 18V and 7V maximum rating
voltages for AC adapter and USB port inputs respectively.
Other features include external programmable safety timer,
under voltage protection, over voltage protection for AC
adapter supply, battery temperature monitoring, power
supply status indicators and charge status indicator.
Features
Automatic Input Supplies Selection
18V Maximum Rating for AC Adapter
Integrated Selectable 100mA and 500mA USB
Charge Current
Internal Integrated Power MOSFETs
AC Adapter Power Good Status Indicator
Charge Status Indicator
External Capacitor Programmable Safety Timer
Under Voltage Protection
Over Voltage Protection
Automatic Recharge Feature
Battery Temperature Monitoring
Small 16-Lead WQFN Package
Thermal Feedback Optimizing Charge Rate
Power Path Controller
RoHS Compliant and Halogen Free
Applications
Digital Cameras
Cellular Phones
PDAs , Smart Phones and MP3 Players
Portable Instruments
Pin Configurations
(TOP VIEW)
SYS
NC
BAT_ON
12
RT9503A
Package Type
QW : WQFN-16L 3x3 (W-Type)
ACIN
USB
CHG_S
AC_PGOOD
1
2
3
4
AC_ON
Ordering Information
16 15 14 13
BATT
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
GND
17
5
6
7
8
11
10
TS
TIMER
9
EN
ISETA
WQFN-16L 3x3
DS9503A-01 April 2011
ISETU
NC
GND
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1
RT9503A
Marking Information
HK=YM
DNN
HK= : Product Code
YMDNN : Date Code
Typical Application Circuit
System
10µF
15
16
3
4
V
IN
Adapter
USB
1µF
1
1µF
2
R
SETA
6
USB
ISETA
GND
5, Exposed Pad (17)
RT9503A
SYS
AC_ON
CHG_S
AC_PGOOD
ACIN
TS
TIMER
1µF
11
10
C
TMR
0.1µF
Chip Enable
+
BAT_ON 13
BATT
12
Battery Pack
EN 9
7 ISETU
Functional Pin Description
Pin No.
1
2
3
4
5,
17 (Exposed Pad)
6
7
8, 14
9
10
11
12
13
15
16
Pin Name
ACIN
USB
CHG_S
USB Charge Supply Input.
Charge Status Indicator Output (open drain).
Ground. The exposed pad must be soldered to a large PCB and connected
to GND for maximum power dissipation.
Wall Adaptor Supply Charge Current Set Point.
USB Supply Charge Current Set Input (active low).
No Internal Connection.
Charge Enable (Active Low).
Safe Charge Timer Setting.
Temperature Sense Input.
Battery Charge Current Output.
Power Path Controller Output. Pull low to turn on the external P-MOSFET.
System Voltage Detecting Input.
P-MOSFET Switch Control Output (open drain).
Pin Function
Wall Adaptor Charge Supply Input.
AC_PGOOD Wall Adaptor Power Good Indicator Output (open drain).
GND
ISETA
ISETU
NC
EN
TIMER
TS
BATT
BAT_ON
SYS
AC_ON
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DS9503A-01 April 2011
RT9503A
Function Block Diagram
USB
ACIN
Charge Input
Selection
SENSE
MOSFET
USB
P-MOSFET
2.5V
OVP
Comparator
+
OVP
-
SENSE
MOSFET
ACIN
P-MOSFET
Timer
TIMER
ISETA
GND
ACIN/USB
V
FB
Temperature
Sense
BATT
TS
OVP
DRV
Precharge
Controller
Logic
AC_ON
1.5k
7.5k
VCC/USB
Logic
BATT
V
OS
+
-
AC_PGOOD
VH
CHG_S
+
-
1µA
1µA
BAT_ON
Hys
ISETU
EN
SYS
Pre-Charge Phase
Fast Charge
Phase
Constant Voltage
Phase &
Re-Charge Phase
Standby Phase
Programmed
Charge Current
Battery
Voltage
Charging
Current
4.1V Recharge
Threshold
1/10 Programmed
Charge Current
2.8V Precharge
Threshold
Charge
Complete
Charging I-V Curve
DS9503A-01 April 2011
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3
RT9503A
Table
RT9503A Flow Chart
Start-Up
Precharge Phase
Fast Charge Phase
Standby/Fault
Recharge Phase
ACIN/USB
Power Up
DISABLE
MODE
PFET OFF
I
BATT
= 0
NO
NO
V
/CE
> 1.4V ?
DISABLE
YES
UVP
V
ACIN
< 3V
and
V
USB
< 3V?
NO
YES
UVP MODE
PFET OFF
I
BATT
= 0
SLEEP
V
ACIN
< V
BATT
and
V
USB
< V
BATT
?
NO
YES
SLEEP MODE
PFET OFF
I
BATT
= 0
Start-Up
1ms Delay
&
Start Timer
V
TS
> 2.5V
or
V
TS
< 0.5V?
YES
NO
OVP
MODE
RECHAR
GE
TEMP
FAULT
V
BATT
> 2.8V?
I
BATT
= 0.1 Charge
Current
/CHG_S Strong Pull
Down
YES
/CHG_S HIGH
IMPEDANCE
NO
NO
I
BATT
= Charge
Current
/CHG_S Strong
Pull Down
YES
YES
YES
V
BATT
> 4.1 V?
YES
NO
V
BATT
> 2.8V?
NO
STANDBY
PFET OFF
I
BATT
= 0
I
BATT
< 0.1 I
CHG
?
YES
V
BATT
> 4.1 V?
NO
NO
t
CHARGE
UP?
YES
? t
CHARGE
UP?
YES
TIME
FAULT
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DS9503A-01 April 2011
RT9503A
Absolute Maximum Ratings
(Note 1)
−0.3V
to 18V
−0.3V
to 7V
−0.3V
to 18V
−0.3V
to 5.5V
1.471W
Supply Input Voltage, ACIN --------------------------------------------------------------------------------------------
Supply Input Voltage, USB --------------------------------------------------------------------------------------------
CHG_S, AC_PGOOD, AC_ON ----------------------------------------------------------------------------------------
Other Pins -----------------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
WQFN-16L 3x3 -----------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
WQFN-16L 3x3,
θ
JA
----------------------------------------------------------------------------------------------------- 68°C/W
WQFN-16L 3x3,
θ
JC
----------------------------------------------------------------------------------------------------- 7.5°C/W
Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------------- 260°C
Junction Temperature --------------------------------------------------------------------------------------------------- 150°C
Storage Temperature Range -------------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) --------------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ---------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 4)
4.5V to 12V
4.1V to 6V
−20°C
to 125°C
−20°C
to 85°C
Supply Input Voltage Range, ACIN -----------------------------------------------------------------------------------
Supply Input Voltage Range, USB -----------------------------------------------------------------------------------
Junction Temperature Range ------------------------------------------------------------------------------------------
Ambient Temperature Range ------------------------------------------------------------------------------------------
Electrical Characteristics
(ACIN = USB = 5V, T
A
= 25°C, unless otherwise specification)
Parameter
Supply Input
Symbol
Test Conditions
Min
--
Typ
3
3
100
300
5
Max
--
--
--
500
15
Unit
V
V
mV
μA
μA
ACIN UVP Rising Threshold Voltage V
UV_ACIN
USB UVP Rising Threshold Voltage V
UV_USB
ACIN/USB UVP Hysteresis
ACIN/USB Standby Current
BATT Sleep Leakage Current
Voltage Regulation
BATT Regulation Voltage
ACIN MOSFET Dropout
USB MOSFET Dropout
Current Regulation
ISETA Set Voltage
(Fast Charge Phase)
Full Charge Setting Range
AC Charge Current Accuracy
V
REG
I
BATT
= 60mA
V
BATT
= 4V, I
CHG_AC
= 1A
V
BATT
= 4V, I
CHG_USB
= High
V
UV_HYS
I
STBY
I
SLEEP
V
BATT
= 3V
V
BATT
= 3V
V
BATT
= 4.5V
V
ACIN
= 4V, V
USB
= 4V,
V
BATT
= 4.5V
--
--
--
--
4.138
400
500
4.2
500
650
4.262
620
800
V
mV
mV
V
ISETA_FCHG
I
CHG_AC
I
CHG_AC
V
BATT
= 3.5V
V
BATT
= 3.8V, R
ISET
= 1.5kΩ
2.43
100
--
2.48
--
500
2.53
1000
--
V
mA
mA
To be continued
DS9503A-01 April 2011
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