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AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
Features
* Ideal for Single-Cell (4.1 V or 4.2 V) and Li-Ion or Li-Pol Packs * Better Than 1% Voltage Regulation Accuracy With Preset Voltages * Optional Cell-Temperature Monitoring Before and During Charge * Integrated Voltage and Current Regulation With Programmable Charge-Current and High or Low-Side Current Sensing * Charge Status Output for Single or Dual Led or Host Processor Interface * Automatic Battery-Recharge Feature * Charge Termination by Minimum Current * Automatic Low-Power Sleep Mode When VCC is Removed *Requires Small Number of External Components * Packaging: 8-Pin MSOP
General Description
The AT1457 series Lithium-Ion (Li-Ion) and Lithium-Polymer (Li-Pol) linear charge ICs are designed for cost-sensitive and compact portable electronics. They combine high-accuracy current and voltage regulation, battery conditioning, temperature monitoring, charge termination, and charge-status indication in a single 8-pin IC. MSOP package options are offered to fit a wide range of end applications. The AT1457 continuously measures battery temperature using an external thermistor. For safety, the AT1457 inhibits charge until the battery temperature is within user-defined thresholds. The AT1457 then charges the battery in three phases: conditioning, constant current, and constant voltage. If the battery voltage is below the low-voltage threshold, V(min), the AT1457 precharges using a low current to condition the battery. The conditioning charge rate is approximately 10% of the regulation current. After conditioning, the AT1457 applies a constant current to the battery. An external sense-resistor sets the current. The sense-resistor can be on either the high or low side of the battery without additional components. The constant-current phase continues until the battery reaches the chargeregulation voltage. The AT1457 then begins the constant-voltage phase. The accuracy of the voltage regulation is better than 1% over the operating- temperature and supply-voltage ranges. For single cells, the AT1457 is offered in two fixed-voltage versions: 4.1 V, and 4.2 V. Charge stops when the current tapers to the charge termination threshold, I(TERM). The AT1457 automatically restarts the charge if the battery voltage falls below the V(RCH) threshold.
Applications
*1-Cell Lithium-Ion And Lithium-Polymer Charger * DSC
Aimtron reserves the right without notice to change this circuitry and specifications.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 1
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
Block Diagram
Pin Configuration
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 2
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC Ordering Information
Part number Package AT1457M MSOP8(4.2V version) AT1457M_GRE MSOP8(4.2V version),Green AT1457AM MSOP8(4.1V version) AT1457AM_GRE MSOP8(4.1V version),Green Marking 1457 1457, date code with one bottom line 1457A 1457A, date code with one bottom line
Pin Description
Pin No. Symbol 1 VCC 2 TS 3 STAT 4 VSS 5 CC 6 VCC1 7 SNS 8 BAT I/O I Supply voltage I Temperature sense input O Charge status output -- Ground O Charge control output I Supply voltage I Current sense input I Voltage sense input Description
Absolute Maximum Ratings
Parameter Power supply voltage Input voltage Sink current (STAT pin) Source current (STAT pin) Output current (CC pin) Total power dissipation Operating free-air temperature range Storage temperature range Lead temperature Symbol VCC V(BAT) V(SNS) V(TS) IOL IOH IO(CC) PD TA Tstg TL Condition -- -- -- -- not to exceed PD not to exceed PD not to exceed PD at 25 soldering, 10 s Rated Value Min. Max. -0.3 +8 -0.3 VCC+0.3 -0.3 VCC+0.3 -0.3 VCC+0.3 -- 20 -- 10 -- 40 -- 300 -20 +85 -40 +125 300 Unit V V V V mA mA mA mW
Recommended Operating Conditions
Parameter Power supply voltage Operating free-air temperature range Symbol VCC TA Min. 4.5 -20 Values Typ. Max. 7 +85 Unit C
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 3
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
Electrical Characteristics
(VIN=4.5V to 7V, TA=-20C to +85C unless otherwise noted. Typical value are at TA=+25C)
Parameter
Symbol
Condition VCC > VCC(min), Excluding external loads V(BAT) V(min), V(BAT) - VCC 0.8V V(BAT) = V(REG) V(SNS) = 5 V V(TS) = 5 V -High-side current sensing configuration Low-side current sensing configuration Voltage at pin SNS, relative to VCC for highside sensing, and to Vss for low-side sensing, 0 TA50 TS pin voltage 58.3 -Voltage at pin SNS, relative to VCC for highside sensing, and to VSS for low-side sensing, 0 TA50 Voltage at pin SNS, relative to VCC for highside sensing, 0TA50, VCC=5V -2.94 3.04
Values Min. Typ. Max.
Unit
VCC Current VCC Sleep current Entire device Input bias current on BAT pin Input bias current on SNS pin Input bias current on TS pin Output voltage Current regulation threshold
I(VCC) I(VCCS) IIB(BAT) IIB(SNS) IIB(TS) VO(REG)
------
2 3 ----
4 6 1 5 5
mA A A A A V V
Battery Voltage Regulation Current Regulation
4.059 4.10 4.141 4.158 4.20 4.242 95.4 100
105 115.5 mV 110 121 mV
V(SNS)
Charge termination Charge Termination current detect Detection threshold Lower temperature threshold Upper temperature threshold Precharge threshold
V(TERM)
4
14
24
mV
Temperature Comparator Precharge Comparator
V(TS1) V(TS2) V(min)
29.1
30 60 3 3.1
30.9 %Vcc 61.8 %Vcc 3.06 3.16 V V
--
13
--
mV
Precharge current regulation
Precharge current regulation
V( PRECHG)
3
13
22
mV
VRCH Comparator (Battery Recharge Threshold) STAT PIN
Recharge threshold Output (low) voltage Output (high) voltage
V(RCH)
VO(REG) -98mV
VO(REG) VO(REG) 100mV 102mV
V V V
VOL(STAT) IOL = 10 mA VOH(STAT) IOH = 5 mA
-VCC0.5
---
0.7 --
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 4
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
Output low voltage CC PIN Sink current IO(CC) VOL(CC) IO(CC) = 5 mA (sink) Not to exceed power rating specification (PD) -5 --1.5 40 V mA
Figure 1: Typical Charge Profile
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 5
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
Figure 2: AT1457 Operational Flow Chart
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 6
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC Typical Application Circuit
Figure 3: 0.5A Charger Using P-Channel MOSFET
Figure 4: 0.5A Charger Using PNP Transistor
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 7
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
Figure 5: 0.5A/0.1A Charger Using P-Channel MOSFET Switching
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 8
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
Application Information 1. Charge Current Formula: Precharge Current:
I PRECHG = V PRECHG R SNS
Current Regulation Charging :
I CHG = V SNS R SNS
Charge Termination Current:
IT = VTERM R SNS
2. High-Side And Low-Side Current Sensing
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 9
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
3. Battery Temperature Monitor The AT1457 continuously monitors temperature by measuring the voltage between the TS and VSS pins. A negative or a positive temperature coefficient thermistor (NTC or PTC) and external voltage divider typically develop this voltage. The AT1457 compares this voltage against its internal VTS1 and VTS2 threshold to determine if charging is allowed.
The resistor value of RT1 and RT2 ars calculated by the following equations: For NTC Thermistor
RT 1 = RT 2 =
5 x RTH x RTC 3 x ( RTC - RTH ) 5 x RTH x RTC [(2 x RTC ) - (7 x RTH )] 5 x RTH x RTC 3 x ( RTH - RTC )
For PTC Thermistor
RT 1 = RT 2 =
5 x RTH x RTC [(2 x RTH ) - (7 x RTC )] RTC is the cold temperature resistance and RTH is the hot temperature resistance of
thermistor.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 10
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
4.Reverse Current Blocking Diode (A) Transistor Circuit Application When using the AT1457 with a PNP Transistor, a reverse-blocking diode is not
required because there is no current path from BAT to VIN. However, it is advisable to still place a diode to the circuit. In the event where the input supply is interrupted or removed during the constant current or constant voltage phases, the battery under charge will discharge through the circuit pass transistor rendering it impossible to turn off. If the circuit is unable to turn off, the reverse leakage will discharge the battery. A Blocking diode will prevent this undesirable effect.
(B) MOSFET Circuit Application An reverse blocking diode is required for the circuit show in Figure 3. The blocking
diode gives the system protection from a shorted input. It also prevent the leakage current of battery when the input power is interrupted or removed.
5.Input Capacitor It is good design practice to place a decoupling capacitor between VCC and VSS
pins. An input capacitor in the range of 0.1F to 10F is recommended. A larger input capacitor in application will minimize switching or power bounce effects when the power supply is "hot plugged" in.
6.Input Capacitor The AT1457 does not need an output capacitor for stability of the device itself,
However, a capacitor connected between BAT and VSS will control the output voltage when the AT1457 is powered up when no battery is connected. If a high impedance load is placed across the BAT pin to VSS, the AT1457 can become unstable. Such a case is possible with aging Li-Ion battery cells. As cells age through repeated charge and discharge cycles, the internal impedance can rise over time. A 10F or larger output capacitor will compensate for the adverse effects of a high impedance load and assure device stability over all operating conditions.
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 11
AT1457
Preliminary Product Information 1-Cell Lithium-Ion And Lithium-Polymer Charge Management IC
Package Outlines (units:mm): MSOP-8
SYMBOL A A1 B C D e E H L S
INCHES MIN MAX 0.037 0.043 0.002 0.006 0.010 0.014 0.005 0.007 0.116 0.120 0.0256 BSC 0.116 0.120 0.188 0.198 0.016 0.026 0 6 0.207 BSC
MILLIMETERS MIN MAX 0.94 1.10 0.05 0.15 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.525 BSC
NOTES -
2F, No.10, Prosperity RD. II, Science-Based Industrial Park, Hsinchu 300,Taiwan, R.O.C. Tel: 886-3-563-0878 WWW: http://www.aimtron.com.tw Fax: 886-3-563-0879 Email: service@aimtron.com.tw 12

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