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Preliminary
RT9501A/B
Advanced Lithium-Ion Linear Battery Charger
General Description
The RT9501 is a single Lithium-Ion or Lithium-Polymer cell linear battery charger which is designed for compact and cost-sensitive handheld devices. It combines charge status indication, charge termination, battery temperature monitoring, and high accuracy current and voltage regulation in a MSOP-8 package. The RT9501 charges the battery in three modes, precharge, constant current, constant voltage. If the battery voltage is below the precharge threshold VO(MIN), the RT9501 precharges the battery with a lower conditioning current. After precharge, the RT9501 applies a constant current to the battery. An external senseresister sets the charge current. The constant voltage mode continues until the battery reaches the regulation voltage. The battery temperature is continuously measured by an external thermistor through the TS pin. The RT9501 inhibits charge until the temperature is within the range defined by users.
Features
For Single Lithium-Ion or Lithium-Polymer Cell Battery Pack (4.1V or 4.2V) A Few External Components are Required Precharge, Constant Current, Constant Voltage Modes Battery Temperature Monitor Charge Status Indication Automatic Battery Recharge Charge Termination Detect Auto Low Power Sleep Mode when VDD Power is Removed MSOP-8 Package
Applications
Digital Cameras PDAs Cellular Phones Information Appliance
Pin Configurations
(TOP VIEW)
VDD TS STAT GND
1 2 3 4 8 7 6 5
Ordering Information
RT9501 Package Type F : MSOP-8 Operating Temperature Range C : Commercial Standard P : Pb Free with Commercial Standard Voltage Version A : 4.1V B : 4.2V
BATT CS FB/CE CC
MSOP-8
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Marking Information
For marking information, contact our sales representative directly or through a RichTek distributor located in your area, otherwise visit our website for detail.
DS9501A/B-03P October 2004 1
RT9501A/B
Typical Application Circuit
Preliminary
Q1 D1 VIN R4
1k
RCS C2 0.1uF to 1uF
+
Battery Pack
NTC
5
CC VDD GND
FB/CE 6 BATT 8 TS STAT 3
2
RT1
7 CS 1 4
C1 0.1uF GND
R3 2k
RT2
Figure 1. Application circuit using P-Channel MOSFET
VIN
RCS
Q1 C2 0.1uF to 1uF
+
Battery Pack
R1 1k
NTC
5 7 1
CC CS
FB/CE BATT TS STAT
6 8 2 3
RT1
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VDD 4 GND C1 0.1uF GND
R3 2k
RT2
Figure 2. Application circuit using PNP transistor
DS9501A/B-03P October 2004 2
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Preliminary Functional Pin Description
Pin Name VDD TS STAT GND CC FB/CE CS BATT Pin Function Supply Voltage Input. Temperature Sense Input. Input from battery temperature monitoring circuit.
RT9501A/B
Charge Status Output. 3-state status indication of charge, charge complete and temperature fault or disable or sleep mode. Ground. Charge Control Output. Current output to drive on external PNP transistor or P-Channel MOSFET for current and voltage regulation. External Feedback Input or Charge Enable Function. Input from controller or finely adjust the battery regulated voltage with external voltage divider. Current Sense Input. Charge current is sensed according to the voltage drop from supply voltage to this pin. Battery Voltage input. Input directly from battery voltage.
Function Block Diagram
BATT VDD VDD
+
Sleep Mode Detection CC Control FB2
+ -
CS VREF1 FB2 VREF2
TS1 Trip +
CV Control
+ +
TS
TS2 Trip +
Precharge Control Logic
+ Recharge
FB2 VREF3 FB2 VREF4 CC VDD
Internal FB
FB/CE
Feedback Determination & Enable Control FB2
STAT GND
DS9501A/B-03P October 2004 3
RT9501A/B
Absolute Maximum Ratings
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Preliminary
(Note 1)
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Supply Voltage --------------------------------------------------------------------------------------------------------- -0.3V to 7V Storage Temperature Range ---------------------------------------------------------------------------------------- -65C to 150C Power Dissipation, PD @ TA = 25C MSOP8 ------------------------------------------------------------------------------------------------------------------ 300mW Package Thermal Resistance MSOP8, JA ------------------------------------------------------------------------------------------------------------ 80C/W Operation Junction Temperature Range -------------------------------------------------------------------------- -40C to 125C Junction Temperature ------------------------------------------------------------------------------------------------- 150C ESD Susceptibility (Note 2) HBM (Human Body Mode) ------------------------------------------------------------------------------------------ 2kV MM (Machine Mode) -------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 3)
Supply Input Voltage -------------------------------------------------------------------------------------------------- 4.5V to 7V Junction Temperature Range ---------------------------------------------------------------------------------------- -20C to 70C
Electrical Characteristics
(TA = 25C, unless otherwise specification)
Parameter Operating Current VDD Sleep Current Input Bias Current @ BATT pin Input Bias Current @ CS pin Input Bias Current @ TS pin Input Bias Current @ FB/CE pin Input Low Voltage @ CE pin Input High Voltage @ CE pin Feedback Voltage @ FB pin Output Voltage Current Regulation Threshold Charge Terminated Current Detect Threshold Lower Temperature Threshold Upper Temperature Threshold Precharge Threshold Precharge Current Regulation Recharge Threshold
Symbol IDD(OPE) IDD(SLP) IBATT ICS ITS ICE VCE VCE VFB
Test Condition 4.5V < VDD < 7V, Excluding external loads VBATT -VDD 0.2V VBATT = VO(REG), VBATT - VDD 0.2V VCS =5V, VBATT - VDD 0.2V VTS =5V, VBATT - VDD 0.2V VCE =5V, VBATT - VDD 0.2V
Min -------VDD-1.5 2.048
Typ 1 -1.5 -----2.10 4.10 4.20 110 12 30 60 2.9 14
Max 2 1 2.5 1 1 1 1.5 -2.152 4.141 4.242 121 22 30.9 61.8 3.0 24
Units mA A A A A A V V V V V mV mV %VDD %VDD V mV
RT9501A VO(REG) VI(SNS) V(TERM) VTS1 VTS2 VO(MIN) V(PRE) VO(RCH) RT9501B VI(SNS) = VDD - VCS
4.059 4.158 100 2 29.1 58.3 2.8 4
VO(REG) - V O(REG)- VO(REG) - V 140mV 100mV 60mV To be continued
DS9501A/B-03P October 2004
4
Preliminary
Parameter Symbol Test Condition Min -VDD-0.5 -5
RT9501A/B
Typ 0.4 ---Max 0.6 -1.5 40 V mA Units V
Output (Low) Voltage @ STAT pin VSTAT(LOW) IOL = 10mA Output (High) Voltage @ STAT pin VSTAT(HIGH) IOH = 5mA Output Low Voltage @ CC pin Sink current @ CC pin VCC(LOW) ICC(SINK) IO(CC) = 5mA ( sink ) Not to exceed power rating specification (PD)
Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. Devices are ESD sensitive. Handling precaution recommended. Note 3. The device is not guaranteed to function outside its operating conditions.
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DS9501A/B-03P October 2004 5
RT9501A/B
Application Information
Charge Profile
Precharge mode
Preliminary
Constant current regulation mode
Constant voltage regulation and charge termination mode
Recharge mode
Regulation voltage Recharge voltage Regulation current
Precharge threshold voltage
Precharge current = Charge termination current
Figure 3. Typical charge profile
Detection First, the FB/CE pin must connect to VDD or a voltage divider to enable the charge function. And then if a battery is already inserted and the input power source is absent, the RT9501 will enter sleep mode to prevent draining power from battery. When input power source and battery are both existed, another detection is the battery temperature. The TS pin voltage must be in the allowed range as shown in Figure 6 and the electrical characteristics, and then the RT9501 will start the charge cycle according to the battery voltage conditions. Precharge Mode When the battery voltage is lower than the precharge threshold VO(MIN), the RT9501 begins to charge the battery in precharge mode. In this condition, the precharge current is set at approximately 10% of the constant regulation current. The purposes of small precharge current are to minimize the power dissipation on the external switch during the precharge period and to revive deeply discharged battery cells.
VIN R4
Constant Current Regulation Charge Mode When the battery voltage is between the precharge threshold VO(MIN) and the regulation voltage VO(REG), the RT9501 starts the constant current regulation charge mode. RT9501 monitors charge current with voltage drop between two terminals of a sense-resistor, RCS, which connects to pin VDD and CS. The following equation can calculate the desired charging current.
IO(REG) = VI(SNS) RCS
RCS
Q1
Battery
FB/CE CS VDD GND
CC BATT TS STAT
Figure 4
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DS9501A/B-03P October 2004 6
Preliminary
Constant Voltage Regulation and Charge Termination Mode When the battery voltage reaches the regulation voltage VO(REG), the constant voltage feedback control starts, and then the charge current begins to decrease as the typical charge profile shown. As the charge current decreases to lower than charge terminated current threshold, the RT9501 will terminate the charge cycle. Recharge Mode After the charge termination mode, if the battery voltage falls to lower than the recharge threshold voltage VO(RCH), the RT9501 will begin a new charge cycle according to the battery voltage. Battery Temperature Detection The RT9501 continuously detects the battery temperature by measuring the TS pin voltage. A NTC or PTC thermistor can parallel with RT2 to deviate the TS pin voltage. (As shown in Figure 5) The TS pin voltage must be within normal temperature voltage range that is shown in Figure 6 and electrical characteristics, and then RT9501 can start working normally. The RT1 and RT2 can be derived from following equations. For NTC Thermistors:
RCS VIN R4 Q1
RT9501A/B
Battery Pack
+
C2 RT1 FB/CE CS VDD RT2 STAT CC BATT TS GND
Thermistor
Figure 5
VDD
Temperature Fault Range
VTS2
Normal Temperature Range
VTS1
Temperature Fault Range
GND
Figure 6
FB/CE Pin Functions This pin has two functions, one is to enable/disable the charge function, and the other is to finely adjust battery regulation voltage. Connect this pin to VDD to enable RT9501, and connect to ground to disable it (Figure 7). If this pin is connected to a voltage divider as shown in Figure 8, it can be a 2.1V reference voltage to adjust the output regulation voltage as desired.
RCS VIN
RT1 =
5 x RTH x RTL 3 x (RTL - RTH)
5 x RTH x RTL [(2 x RTL) - (7 x RTH)]
RT2 =
Q1 R4
Battery
For PTC Thermistors:
RT1 = RT2 =
5 x RTH x RTL 3(RTH - RTL) 5 x RTH x RTL [(2 x RTH) - (7 x RTL)]
GPIO
RCE CE CS VDD STAT CC BATT TS GND
Where RTL is the resistance value in lowest desired operation temperature and RTH is the resistance value in highest desired operation temperature. The resistances of thermistors are specified by the thermistor manufacturer. If the temperature monitoring function is not desired, there's an easy method to set RT1 and RT2 at the same value and disconnect the thermistor to disable this function.
Figure 7. For CE pin Function
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DS9501A/B-03P October 2004 7
RT9501A/B
VIN RCS R4 Q1
Preliminary
Selecting Input/Output Capacitor
Battery RFB1
FB CS VDD STAT
CC BATT TS GND RFB2
In analog circuit applications, to place a high-frequency decoupling capacitor nearby the controller IC between input power source and ground is very important. A 0.1uF ceramic is recommended. If a high ripple and noise input power is chosen, it should have enough capacitance to reduce the disturbance. A 0.1uF to 1uF output capacitor is recommended to control the output voltage and keep the output voltage ripple small when the battery is disconnected.
Figure 8. For FB pin Function
VO(REG) = 2.1x (1+ RFB1 RFB2 )V
Charge status indication The RT9501 indicates the status of the charger on the 3-state STAT pin. The following table shows the statuses of this pin.
Condition In battery charging cycle Charge cycle completed Temperature fault or charge function disable or sleep mode STAT Pin High Low High Impedance
Selecting an External PNP Pass-Transistor or P-Channel MOSFET: The RT9501 drives an external PNP transistor or P-Channel MOSFET to control the charging current. The specifications must be concerned are the voltage and current rating and package power dissipation. The external switch is performed as a linear regulator. The maximum power loss occurs when the constant current regulation starts at the beginning, and it can be calculated approximately from following equation: P D(MAX) = I(SNS) x (V DD - 0.1V - 2.8V) I(SNS) is the constant regulation current. The minimum voltage drop between the sense-resistor is 100mV, and the minimum precharge threshold voltage is 2.8V. The external pass device with PCB heatsinking must be rated for the maximum power dissipation.
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DS9501A/B-03P October 2004 8
Preliminary Outline Dimension
D L
RT9501A/B
E
E1
e A A1 b A2
Symbol A A1 A2 b D e E E1 L
Dimensions In Millimeters Min 0.810 0.000 0.750 0.220 2.900 0.650 4.800 2.900 0.400 5.000 3.100 0.800 Max 1.100 0.150 0.950 0.380 3.100
Dimensions In Inches Min 0.032 0.000 0.030 0.009 0.114 0.026 0.189 0.114 0.016 0.197 0.122 0.031 Max 0.043 0.006 0.037 0.015 0.122
8-Lead MSOP Plastic Package
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.
DS9501A/B-03P October 2004 9

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