RT9503
Fully Integrated Linear Single Cell Li-Ion Battery Charger
with Power Path
General Description
The RT9503 is a fully integrated low cost single-cell Li-
Ion battery charger IC ideal for portable applications. The
RT9503 is capable of being powered up from AC adapter
and the USB (Universal Serial Bus) port inputs. The
RT9503 can automatically detect and select the AC
adapter and the USB port as the power source for the
charger. The RT9503 enters sleep mode when both
supplies are removed.
The RT9503 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 ratings100mA and 500mA, while the AC adapter
charge current can be programmed up to 1A with an
external resister. The internal thermal feedback circuitry
regulates the die temperature to optimize the charge rate
for all ambient temperatures.
The RT9503 features 18V and 7V maximum rating voltages
for AC adapter and USB port inputs respectively. The other
features are external programmed 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 FETs
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 100% Lead (Pb)-Free
Applications
Digital Cameras
Cellular Phones
PDAs and Smart Phones and MP3
Portable Instruments
Pin Configurations
(TOP VIEW)
NC
BAT_ON
12
AC_ON
ACIN
USB
CHG_S
AC_PGOOD
Ordering Information
RT9503
Package Type
QW : WQFN-16L 3x3 (W-Type)
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.
1
2
3
4
16 15 14 13
SYS
BATT
TS
TIMER
EN
GND
17
5
6
7
8
11
10
9
WQFN-16L 3x3
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
DS9503-03 April 2011
ISETU
NC
GND
ISETA
www.richtek.com
1
RT9503
Typical Application Circuit
System
10uF
15
16
3
4
V
IN
Adapter
USB
1uF
1
1uF
2
6
USB
ISETA
GND
5, Exposed Pad (17)
RT9503
SYS
AC_ON
CHG_S
AC_PGOOD
ACIN
TS
TIMER
1uF
11
10
C
T
0.1uF
Chip Enable
+
BAT_ON 13
12
Battery Pack
BATT
EN 9
7 ISETU
Functional Pin Description
Pin No.
1
2
3
4
5
6
7
8, 14
9
10
11
12
13
15
16
Pin Name
ACIN
USB
CHG_S
AC_PGOOD
GND
ISETA
ISETU
NC
EN
TIMER
TS
BATT
BAT_ON
SYS
AC_ON
Pin Function
Wall Adaptor Charge Input Supply.
USB Charge Input Supply.
Charge Status Indicator Output (open drain).
Wall Adaptor Power Good Indicator Output (open drain).
Ground.
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, low to turn on the external P-MOSFET.
System Voltage Detecting Pin.
P-MOSFET Switch Control Output (open drain).
The exposed pad must be soldered to a large PCB and connected to GND for
maximum power dissipation.
17 (Exposed Pad) GND
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2
DS9503-03 April 2011
RT9503
Function Block Diagram
USB
ACIN
OVP
Comparator
+
OVP
-
2.5V
Charge Input
Selection
SENSE
MOSFET
USB
P-MOSFET
SENSE
MOSFET
ACIN
P-MOSFET
Timer
TIMER
ISETA
GND
2.5V
V
REF
Thermal
Sense
125 C
ACIN/USB
V
FB
Temperature Fault
Temperature
Sense
BATT
0.5V
0.25V
DRV
Precharge
Loop Controller
OVP
TS
AC_ON
Logic
1.5k
7.5k
Termination
Comparator
-
0.25V
0.9V
+
-
+
Charge
Disable BATT
V
OS
V
REF
Thermal
Sense
VCC/USB
PGOOD
Logic
VH
CHG_S
+
-
Hys
+
-
1uA
1uA
BAT_ON
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
DS9503-03 April 2011
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3
RT9503
Table
RT9503 Flow Chart
Start-Up
Precharge Phase
Fast Charge Phase
Standby/Fault
Recharge Phase
ACIN/USB
Power Up
V
/CE
> 1.4V ?
DISABLE
YES
DISABLE
MODE
PFET OFF
I
BATT
= 0
NO
NO
UVP
V
ACIN
< 4.3V
and
< 3.9V?
V
USB
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
I
BATT
< 0.1 I
CHG
?
YES
STANDBY
PFET OFF
I
BATT
= 0
V
BATT
> 4.1 V?
NO
NO
T
CHARGE
UP?
YES
? T
CHARGE
UP?
YES
TIME
FAULT
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DS9503-03 April 2011
RT9503
Absolute Maximum Ratings
(Note 1)
−0.3V
to 18V
−0.3V
to 7V
−0.3V
to 18V
−0.3V
to 5.5V
1.667W
Supply Input Voltage, ACIN ---------------------------------------------------------------------------------------------
Supply Input Voltage, USB ----------------------------------------------------------------------------------------------
CHG_SB, 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
------------------------------------------------------------------------------------------------------- 60°C/W
WQFN-16L 3x3,
θ
JC
------------------------------------------------------------------------------------------------------ 8.2°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
4.1
Typ
4.3
3.9
100
300
50
5
Max
4.5
4.1
140
500
100
15
Units
V
V
mV
uA
uA
uA
ACIN UVP Rising Threshold Voltage V
UV_ACIN
USB UVP Rising Threshold Voltage V
UV_USB
ACIN/USB UVP Hysteresis
ACIN/USB Standby Current
ACIN/USB Shutdown Current
BATT Sleep Leakage Current
Voltage Regulation
BATT Regulation Voltage
ACIN MOSFET Dropout
ACIN 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
= 1A
V
BATT
= 4V, I
USB
= High
V
UV_HYS
I
STBY
I
SHDN
I
SLEEP
V
BATT
= 3V
V
BATT
= 3V
V
BA TT
= 4.5V
V
EN
= High
V
ACIN
= 4V, V
USB
= 4V,
V
BATT
= 4.5V
3.7
40
--
--
--
4.158
400
500
4.2
500
650
4.242
620
800
V
mV
mV
V
ISETA_FCHG
V
BATT
= 3.5V
I
CHG_AC
I
CHG_AC
V
BATT
= 3.8V, R
ISET
= 1.5kΩ
2.43
100
--
2.48
--
500
2.53
1000
--
V
mA
mA
To be continued
DS9503-03 April 2011
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