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Description
SE9017 is a complete constant-current & constant voltage linear charger for single cell lithium-ion and Lithium-Polymer batteries. Its SOT-23 package and low external component count make SE9017 ideally suited for portable applications. Furthermore, the SE9017 is specifically designed to work within USB power specification. At the same time, SE9017 can also be used in the standalone lithium-ion and Lithium-polymer battery chargers. No external sense resistor is needed, and no blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The SE9017 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the SE9017 automatically enters a low current stage, dropping the battery drain current to less than 2uA. The SE9017 can be put into shutdown mode, reducing the supply current to 20uA. Other features include charge current monitor, undervoltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input voltage. SE9017 is intentionally designed to have slightly negative Tempco. This provides extra protection to Lithium battery during charging.
Features
Programmable Charge Current Up to 800mA. No MOSFET, Sense Resistor or Blocking Diode Required. Constant-Current/Constant-Voltage Operation with Thermal Protection to Maximize Charge Rate without Risk of Overheating. Charges Single Cell Li-Ion Batteries Directly from USB Port. Preset 4.2V Charge Voltage with 1% Accuracy. 20uA Supply Current in Shutdown. 2.9V Trickle Charge Threshold Soft-Start Limits Inrush Current. Available in 6-Lead SOT-23 and PSOP-8 (Exposed Pad) Packages. RoHS Compliant and 100% Lead (Pb)-Free
Application
Cellular Telephones, PDA's, MP3 Players. Charging Docks and Cradles Bluetooth Applications
Application Diagram
Pin Configuration
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Absolute Maximum Rating (1)
Parameter Input Supply Voltage PROG Voltage BAT Voltage CHRG Voltage BAT Short-Circuit Duration Thermal Resistance, Junction-to-Ambient BAT Pin Current PROG Pin Current Maximum Junction Temperature Storage Temperature Lead Temperature (Soldering, 10 sec) JA IBAT IPROG TJ TS Symbol VCC VPROG VBAT VCHRG Value 7 VCC+0.3 7 7 Continuous 250 (SOT-23-6) 75(PSOP8) 800 800 125 -65 to +125 300 C/W mA A C C C Units V V V V
Operating Rating (2)
Parameter Supply Input Voltage Junction Temperature Symbol VIN TJ Value -0.3 to +7 -40 to +85 Units V C
Electrical Characteristics
VIN = 5V; TJ = 25C; unless otherwise specified. Symbol VCC ICC Parameter Input Supply Voltage Input Supply Current Charge Mode , RPROG = 10k Standby Mode (Charge Terminated)
Shutdown Mode(RPROG Not Connected, VCC < VBAT, or VCC < VUV)
(3)
Conditions
Min 4.25
Typ 110 70 20
Max 6 500 40 4.242 130 +/-5 +/-5 +/-5
Unit V A A A V mA mA A A A mA
VFLOAT IBAT
Regulated Output (Float) Voltage BAT Pin Current
IBAT = 30mA, ICHRG = 5mA RPROG = 10k, Current Mode RPROG = 2k, Current Mode Standby Mode, VBAT = 4.2V
Shutdown Mode (RPROG Not Connected)
4.158 90 0
4.2 106 530 +/-1 +/-0.5 +/-1 10
Sleep Mode, VCC = 0V ITRIKL VTRIKL Trickle Charge Current Trickle Charge Threshold Voltage VBAT < VTRIKL, RPROG = 10k RPROG = 10k, VBAT Rising 2.8
2.9
3.0
V
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Electrical Characteristics (Continued)
VIN = 5V; TJ = 25C; unless otherwise specified Symbol VUV VUVHYS VMSD VASD ITERM VPROG ICHRG VCHRG VRECHRG TLIM tSS tRECHARGE tTERM IPROG Parameter VCC Undervoltage Lockout Threshold VCC Undervoltage Lockout Hysteresis Manual Shutdown Threshold Voltage PROG Pin Rising PROG Pin Falling VCC - VBAT Lockout Threshold Voltage C/10 Termination Current Threshold VCC from Low to High VCC from High to Low RPROG = 10k RPROG = 2k PROG Pin Voltage CHRG Pin Weak Pull-Down Current CHRG Pin Output Low Voltage Recharge Battery Threshold Voltage Thermal Protection Temperature Soft-Start Time Recharge Comparator Filter Time Termination Comparator Filter Time PROG Pin Pull-Up Current IBAT = 0 to 1000V/RPROG VBAT High to Low IBAT Falling Below ICHG/10 RPROG = 10k, Current Mode VCHRG = 3V ICHRG = 5mA VFLOAT - VRECHRG 0.9
(4)
Conditions From VCC Low to High
Min
Typ 3.4 100 1.25 1.2 100 30 0.1 0.1 1.03 15 0.6 100 120 100 1 1000 1
Max
Unit V mV V V mV mV mA/mA mA/mA
1.1
V A V mV C s ms s A
Note 1: Exceeding the absolute maximum rating may damage the device. Note 2: The device is not guaranteed to function outside its operating rating. Note 3: Supply current includes PROG pin current (approximately 100A) but does not include any current delivered to the battery through the BAT pin (approximately 100mA). Note 4: ITERM is expressed as a fraction of measured full charge current with indicated PROG resistor.
Pin Functions
Pin Pin Function Description
P Positive Input Supply Voltage. Provides power to the charger. VCC can range from 4.25V to 6.5V and should be bypassed with at least a 1F capacitor.
Pin
Pin Function Description
Open-Drain Charge Status Output. When the battery is charging, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed, a weak pull-down of approximately 20uA is connected to the CHRG pin, indicating an "AC present" condition.
VCC
CHRG
GND
Ground.
PROG
Charge Current Program, Charge Current Monitor and Shutdown Pin. Open-Drain Charge Termination Status Output. When the battery is
Charge Current Output. Provides
charging, the CHRGT pin is pulled high by an external
compenent
BAT
charge current to the battery and regulates the final float voltage to 4.2V.
CHRGT
such as an LED. After the charging is completed, this pin is pulled low by internal N-channel MOSFET and it can be used as a charging termination indicator.
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BLOCK DIAGRAM
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Float Voltage vs Supply Voltage 4.230 4.225 4.220 4.215 VBAT (V) 4.210 4.205 4.200 4.195 4.190 4.185 4.0 4.5 5.0 5.5 VCC (V) 6.0 6.5 RPROG=10k TA=25
IBAT (m A ) 600
Charge Current vs Supply Voltage RPROG=2k 500 400 300 200 100 0 4.0 RPROG=10k 4.5 5.0 5.5 VCC (V)
Float Voltage vs Temperature 4.215
VBAT=4V TA=25
ONSET OF THERMAL REGULATION
6.0
6.5
7.0
Trickle Charge Current vs Supply Voltage 70 60 50 40 ITRIKL (mA) 30 20 10 0 4.0 RPROG=10k VBAT=2.5V TA=25
RPROG=2k
4.210 4.205 VFLOAT (V)
7.0
4.200 4.195 4.190 4.185
4.5
5.0
5.5 VCC (V)
6.0
6.5
20
40
60 80 Temperature ()
100
120
Revision 4/16/2009 Preliminary and all contents are subject to change without prior notice (c) Seaward Electronics Inc., 2007. * www.seawardinc.com.cn * Page 5
Operation
The SE9017 is a single cell lithium-ion battery charger using a constant-current/constant-voltage algorithm. It can deliver up to 800mA of charge current (using a good thermal PCB layout) with a final float voltage accuracy of 1%. The SE9017 includes an internal P-channel power MOSFET and thermal regulation circuitry. No blocking diode or external current sense resistor is required; thus, the basic charger circuit requires only two external components. Furthermore, the SE9017 is capable of operating from a USB power source. current are calculated using the following equations:
RPROG =
1060V 1060V , I CHG = , I CHG RPROG
The charge current out of the BAT pin can be determined at any time by monitoring the PROG pin voltage using the following equation:
I BAT =
VPROG * 1060 RPROG
This actual current will vary from IC to IC. The typical variation is within +/-20%.
Normal Charge Cycle
A charge cycle begins when the voltage at the VCC pin rises above the UVLO threshold level and a 1% program resistor is connected from the PROG pin to ground or when a battery is connected to the charger output. If the BAT pin is less than 2.8V, the charger enters trickle charge mode. In this mode, the SE9017 supplies approximately 1/10 the programmed charge current to bring the battery voltage up to a safe level for full current charging. When the BAT pin voltage rises above 2.8V, the charger enters constant-current mode, where the programmed charge current is supplied to the battery. When the BAT pin approaches the final float voltage (4.2V), the SE9017 enters constant-voltage mode and the charge current begins to decrease. When the charge current drops to 1/10 of the programmed value, the charge cycle ends.
Charge Termination
A charge cycle is terminated when the charge current falls to 1/10th the programmed value after the final float voltage is reached. This condition is detected by using an internal, filtered comparator to monitor the PROG pin. When the PROG pin voltage falls below 100mV for longer than tTERM (typically 1ms), charging is terminated. The charge current is latched off and the SE9017 enters standby mode, where the input supply current drops to 200mA. (Note: C/10 termination is disabled in trickle charging and thermal limiting modes). When charging, transient loads on the BAT pin can cause the PROG pin to fall below 100mV for short periods of time before the DC charge current has dropped to 1/10th the programmed value. The 1ms filter time (tTERM) on the termination comparator ensures that transient loads of this nature do not result in premature charge cycle termination. Once the average charge current drops below 1/10th the programmed value, the SE9017 terminates the charge cycle and ceases to provide any current through the BAT pin. In this state, all loads on the BAT pin must be supplied by the battery. The SE9017 constantly monitors the BAT pin voltage
Programming Charge Current
The charge current is programmed using a single resistor from the PROG pin to ground. The battery charge current is 1060 times the current out of the PROG pin. The program resistor and the charge
Revision 4/16/2009
Preliminary and all contents are subject to change without prior notice (c) Seaward Electronics Inc., 2007. * www.seawardinc.com.cn * Page 6
in standby mode. If this voltage drops below the4.05V recharge threshold (VRECHRG), another charge cycle begins and current is once again supplied to the battery. To manually restart a charge cycle when in standby mode, the input voltage must be removed and reapplied, or the charger must be shut down and restarted using the PROG pin. Figure 1 shows the state diagram of a typical charge cycle.
Undervoltage Lockout (UVLO)
An internal undervoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode until VCC rises above the undervoltage lockout threshold. The UVLO circuit has a built-in hysteresis of 200mV. Furthermore, to protect against reverse current in the power MOSFET, the UVLO circuit keeps the charger in shutdown mode if VCC falls to within 30mV of the battery voltage. If the UVLO comparator is tripped, the charger will not come out of shutdown mode until VCC rises 100mV above the battery voltage.
Charge Status Indicator (CHRG)
The charge status output has three different states: strong pull-down (~10mA), weak pull-down (~20A) and high impedance. The strong pull-down state indicates that the SE9017 is in a charge cycle. Once the charge cycle has terminated, the pin state is determined by undervoltage lockout conditions. A weak pull-down indicates that VCC meets the UVLO conditions and the SE9017 is ready to charge. High impedance indicates that the SE9017 is in undervoltage lockout mode: either VCC is less than 100mV above the BAT pin voltage or insufficient voltage is applied to the VCC pin.
Power On VBAT<2.8V
PROG Reconnected Or UVLO Connection Stops
Trickle Charge Mode 1/10
TH
of Full Current
Chrg LED: Strong Pull-Dn
VBAT>2.8V
Shutdown Mode ICC Drops to < 20A CC/CV Charge Mode Full Current
Chrg LED: Strong Pull-Dn
VBAT>2.8V
Thermal Limiting
An internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 120. This feature protects the SE9017 from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the SE9017. The charge current can be set according to typical (not worst-case) ambient temperature with the assurance that the charger will automatically reduce the current in worst-case conditions.
Chrg: Hi-Z In UVLO WeakPull-Dn Otherwise
VPROG<100mV
Standby Mode No Charge Current
PROG Floated Or UVLO Connection
Chrg LED: Weak Pull-Dn
4.05V>VBAT>2.8V
Figure1.
State Diagram of a Typical Charge Cycle
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Application Hints
Stability Considerations
The constant-voltage mode feedback loop is stable without an output capacitor provided a battery is connected to the charger output. With no battery present, an output capacitor is recommended to reduce ripple voltage. When using high value, low ESR ceramic capacitors, it is recommended to add a 1 resistor in series with the capacitor. No series resistor is needed if tantalum capacitors are used. In constant-current mode, the PROG pin is in the feedback loop, not the battery. The constant-current mode stability is affected by the impedance at the PROG pin. With no additional capacitance on the PROG pin, the charger is stable with program resistor values as high as 20k. However, additional capacitance on this node reduces the maximum allowed program resistor. The pole frequency at the PROG pin should be kept above 100kHz.
Power Dissipation
The conditions that cause the SE9017 to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the IC. Nearly all of this power dissipation is generated by the internal MOSFET--this is calculated to be approximately: PD = (VCC - VBAT) * IBAT The approximate ambient temperature at which the thermal feedback begins to protect the IC is: TA = 120C - PDJA TA = 120C - (VCC - VBAT) * IBAT * JA
Thermal Considerations
Because of the small size of the thin SOT23 package, it is very important to use a good thermal PC board layout to maximize the available charge current. The thermal path for the heat generated by
VCC Bypass Capacitor
Many types of capacitors can be used for input bypassing, however, caution must be exercised when using multilayer ceramic capacitors. Because of the self-resonant and high Q characteristics of some types of ceramic capacitors, high voltage transients can be generated under some start-up conditions, such as connecting the charger input to a live power source. Adding a 1.5 resistor in series with a ceramic capacitor will minimize start-up voltage transients.
the IC is from the die to the copper lead frame, through the package leads, (especially the ground lead) to the PC board copper. The PC board copper is the heat sink. The footprint copper pads should be as wide as possible and expand out to larger copper areas to spread and dissipate the heat to the surrounding ambient. Other heat sources on the board, not related to the charger, must also be considered when designing a PC board layout because they will affect overall temperature rise and the maximum charge current.
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Applications No-load indications
Put a 1uF capacitor between BAT and GND . This makes up of a No-load indications circuit as shown below. If there is not a battery connected to BAT and GND of SE9017 then we can see that LED-R will be flashing at 2.5 Hz/S. If there is a battery connected to BAT and GND Pin of SE9017. Than SE9017 enters normal chargeing cycle.
4.5V to 6.5V 330 ohm 104
Vcc
LED-G LED-R
CHRG
BAT
105
SE9017
CHRGT PROG
GND
10K
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OUTLINE DRAWING SOT-23-6L
OUTLINE DRAWING PSOP-8
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Customer Support
Seaward Electronics Incorporated - China Section B, 2nd Floor, ShangDi Scientific Office Complex, #22 XinXi Road Haidian District, Beijing 100085, China Tel: 86-10-8289-5700/01/05 Fax: 86-10-8289-5706 Seaward Electronics Corporation - Taiwan 2F, #181, Sec. 3, Minquan East Rd, Taipei, Taiwan R.O.C Tel: 886-2-2712-0307 Fax: 886-2-2712-0191 Seaward Electronics Incorporated - North America 1512 Centre Pointe Dr. Milpitas, CA95035, USA Tel: 1-408-821-6600 Last Updated - 4/16/2009
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