Document
RT9502
Linear Single Cell Li-Ion Battery Charger IC with Dual Input Supply
General Description
The RT9502 is a fully integrated low cost single-cell LiIon battery charger IC ideal for portable applications. The RT9502 is capable of being powered up from AC adapter and USB (Universal Serial Bus) port inputs. The RT9502 can automatically detect and select the AC adapter and the USB port as the power source for the charger. The RT9502 enters sleep mode when both supplies are removed.
The RT9502 optimizes the charging task by using a control algorithm including precondition 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 resister. The internal thermal feedback circuitry regulates the die temperature to optimize the charge rate for all ambient temperatures.
The RT9502 features 18V and 7V maximum rating voltages for AC adapter and USB port inputs respectively. The other features are under voltage protection, over voltage protection for AC adapter supply and battery temperature monitoring.
Features
z Automatic Input Supplies Selection z 18V Maximum Rating for AC Adapter z Integrated Selectable 100mA and 500mA USB
Charge Current z Internal Integrated P-MOSFETs z AC Adapter Power Good Status Indicator z Charge Status Indicator z Under Voltage Protection z Over Voltage Protection z Automatic Recharge Feature z Battery Temperature Monitoring z Small 10-Lead WDFN Package z Thermal Feedback Optimizing Charge Rate z RoHS Compliant and 100% Lead (Pb)-Free
Applications
z Digital Cameras z Cellular Phones z Personal Digital Assistants (PDAs) z MP3 Players z Hand Held PCs
Pin Configurations
Ordering Information
RT9502 Package Type QW : WDFN-10L 3x3 (W-Type)
Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free)
(TOP VIEW)
ACIN 1
USB 2 CHG_S 3 PGOOD 4
GND 5
GND
11
9
10 BATT 9 TS 8 EN 7 ISETU
ISETA
WDFN-10L 3x3
Note : Richtek products are :
` RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
For marking information, contact our sales representative directly or through a Richtek distributor located in your area.
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RT9502
Typical Application Circuit
AC Adapter
RT9502
1 ACIN
10 BATT
1uF
+
Battery Pack
USB
2 USB 1uF
To System To System
3 CHG_S 4 PGOOD
5, Exposed Pad(11) GND
9 TS
8 EN
7 ISETU ISETA 6
Chip Shutdown Chip Enable
H : 500mA L : 100mA
RSET
0.1uF to 10uF
Pre-Charge Phase
Fast Charge Phase
Programmed Charge Current
Constant Voltage
Phase &
Re-Charge Phase
Standby Phase
4.1V Recharge Threshold
Battery Voltage
Charging Current
1/10 Programmed Charge Current
2.8V Precharge Threshold
Charge Complete
Functional Pin Description
Pin No.
Pin Name
Pin Function
1 ACIN 2 USB 3 CHG_S 4 PGOOD 5 GND 6 ISETA 7 ISETU 8 EN 9 TS 10 BATT
11 (Exposed Pad) GND
AC Adaptor Charge Input Supply. USB Charge Input Supply. Charge Status Indicator Output (open drain). Power Good Indicator Output (open drain). Ground. Wall Adaptor Supply Charge Current Set Point. USB Supply Charge Current Set Input (active low). Charge Enable Input (active low).
Temperature Sense Input. Battery Charge Current Output. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation.
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DS9502-02 April 2011
Function Block Diagram
USB
SENSE MOSFET
USB P-MOSFET
RT9502
Charge Input Selection
ACIN
2.5V
OVP Comparator
+ OVP -
SENSE MOSFET
ACIN P-MOSFET
ISETA GND
1.5k
7.5k
1uA
2.5V 0.5V 0.25V Precharge
VREF ACIN/USB
Thermal Sense 115 C
VFB
DRV
VCC/USB Loop Controller
Termination Comparator
-
0.25V 0.9V
+ -
Charge Disable
+
1uA
VREF Thermal Sense
Logic
Temperature Fault
Temperature Sense
BATT
PGOOD CHG_S
ISETU EN
TS
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SLEEP
UVP / OVP
DISABLE
RT9502
RT9502 Flow Chart Start-Up
ACIN/USB Power Up
VEN > 1.4V ?
NO
VACIN > 6.5V or (VACIN < 4.4V and
VUSB < 4.4V) ?
NO
VACIN < VBATT and
VUSB < VBATT ? NO
1ms Delay
Table
Precharge Phase
Fast Charge Phase
Standby/Fault
Recharge Phase
YES YES
YES
DISABLE MODE P-MOSFET OFF
IBATT=0
OVP/UVP MODE P-MOSFET OFF
IBATT=0
SLEEP MODE P-MOSFET OFF
IBATT=0
Start-Up
VTS > 2.5V or
VTS < 0.5V? NO
VBATT > 2.8V?
NO
YES
YES IBATT = 0.1 Charge
Current /CHG_S Pull Down
TEMP FAULT/CHG_S
HIGH IMPEDANCE
IBATT = Charge Current
/CHG_S Pull Down
YES NO
VBATT ~ 4.2V, IBATT < 0.1 ICHG?
YES
STANDBY PFET OFF
VBATT = 4.2V, IBATT = 0
RECHARGE
YES VBATT > 4.1 V? NO
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RT9502
Absolute Maximum Ratings (Note 1)
z ACIN Input Voltage -------------------------------------------------------------------------------------------------------- −0.3V to 18.