 features

Two-Cell Lithium-Ion Battery Protection IC
FEATURES
DESCRIPTION
Ultra-Low Quiescent Current at 10µA (VCC=7V, The AIC1802 battery protection IC is designed to protect lithium-ion batteries from damage due Ultra-Low Power-Down Current at 0.2µA (VCC overcurrent for two series cells in portable phones and laptop computers. It can be a part Precision Overcharge Protection Voltage of the low-cost charge control system within a Safe and full utilization charging is ensured by the accurate ±30mV overcharge detection. Built-in Delay Circuits for Overcharge, Over-discharge and Overcurrent Protection. Three different specification values for overcharge protection voltage are provided for Overcharge and Overdischarge Delay Time various protection requirements. The very low standby current drains little current from the Built-in Cell-balancing Bleeding Network under APPLICATIONS
Protection IC for Two-Cell Lithium-Ion Battery TYPICAL APPLICATION CIRCUIT
*CTC & CTD are optional for delay time adjustment.
**R1 & R2: Refer application informations.
Protection Circuit for Two-Cell Lithium-Ion Battery Pack
Analog Integrations Corporation
3A1, No.1, Li-Hsin Rd. I , Science Park , Hsinchu 300, Taiwan , R.O.C. ORDERING INFORMATION
OVERCHARGE PROTECTION Example: AIC1802APSTR VOLTAGE ABSOLUTE MAXIMUM RATINGS
Supply Voltage .……………. 18V
DC Voltage Applied on VC, CS, OC, OD Pins .……………. 18V
DC Voltage Applied on TC, TD Pins .………………….……. 5V
.….…………. -40°C~85°C
Storage Temperature Range .…………………. - 65°C~150°C
Junction Temperature .………………….………………… 125°C
Lead Temperature (Soldering 10s) .………………….…. 260°C
Thermal Resistance Junction to Case SOP-8 .……………… 40°C/W
Thermal Resistance Junction to Ambient SOP-8 .…………… 160°C/W
(Assume no ambient airflow, no heatsink) Absolute Maximum Rating are those value beyond which the life of a device may be impaired.
TEST CIRCUIT
ELECTRICAL CHARACTERISTICS (TA=25°C, unless otherwise specified.)
PARAMETER
TEST CONDITIONS
MIN. TYP. MAX. UNIT
ELECTRICAL CHARACTERISTICS (Continued)
PARAMETER
TEST CONDITIONS
MIN. TYP. MAX. UNIT
Note1: Specifications are production tested at TA = 25°C. Specifications over the -40°C to 85°C operating Temperature
range are assured by design, characterization and correlation with Statistical Quality Controls (SQC). TYPICAL PERFORMANCE CHARACTERISTICS
Fig. 2 Power-down Current vs. Supply Voltage Fig. 3 Overcharge Protection Voltage vs. Temperature Fig. 4 Overcurrent Protection Voltage vs. Temperature TYPICAL PERFORMANCE CHARACTERISTICS (Continued)
Fig. 6 Power-Down Current vs. Temperature Fig. 7 Overdischarge Protection Voltage vs. Temperature Fig. 8 Overcharge Release Voltage vs. Temperature Fig. 9 Overdischarge Release Voltage vs. Temperature BLOCK DIAGRAM
PIN DESCRIPTIONS
turning off the charge control MOSFET M2. PIN 7: CS - Input pin for current sensing. PIN 8: VCC - Power supply pin. It is to be PIN 4: GND - Ground pin. This pin is to be APPLICATION INFORMATION

THE OPERATION
circuit for the cell under overcharge condition. Overcharge Protection
When the voltage of either of the battery cells Charge Detection after Overdischarge
When overcharge occurs, the discharge control beyond the overcharge delay time period, charging is inhibited by the turning-off of the inhibited. However, charging is still permitted charge control MOSFET M2. The overcharge through the parasitic diode of M1. Once the charger is connected to the battery pack, the AIC1802 immediately turns on all the timing charging is immediately released when the generation and detection circuitry and goes into voltage of the overcharged cell becomes lower normal mode. Charging is determined to be in progress if the voltage between CS and GND is OCR (overcharge release voltage) through below –0.4V (charge detection threshold voltage Overdischarge Protection
When the voltage of either of the battery cells Overcurrent Protection
In normal mode, the AIC1802 continuously voltage) beyond the overdischarge delay time monitors the discharge current by sensing the period, discharging is inhibited by the turning-off voltage of CS pin. If the voltage of CS pin exceeds VOIP (overcurrent protection voltage) beyond overcurrent delay time TOI period, the and can be extended by adding a capacitor C overcurrent protection circuit operates and Inhibition of discharging is immediately released discharging is inhibited by turning-off of the when the voltage of the overdischarged cell discharge control MOSFET M1. Discharging must be inhibited for at least 256mS after overcurrent takes place to avoid damage to switching transient between VBAT+ and VBAT- Power-Down after Overdischarge
terminals. The overcurrent condition returns to When overdischarge occurs, the AIC1802 will go the normal mode when the load is released and into power-down mode, turning off all the timing the impedance between the VBAT+ and VBAT- generation and detection circuitry to reduce the terminals is 10MΩ or higher. For the sake of quiescent current to 0.8µA (VCC=4.8V). In the protection of the external MOSFETs, the larger the CS pin voltage (which means the larger overdischarged while the other under overcharge discharge current) the shorter the overcurrent condition, the AIC1802 will turn off all the delay time. The relationship between voltage of detection circuits except the overcharge detection Unbalanced Discharge after Overcharge
When either of the battery cells is overcharged, the AIC1802 will automatically discharge the overcharged cell at about 7.7mA until the voltage of the overcharged cell is equal to the voltage of Selection of External Control MOSFETs
the other cell. If the voltage of the other cell is Because the overcurrent protection voltage is below VOCR, the internal cell-balance “bleeding” preset, the threshold current for overcurrent will proceed until the voltage of the overcharged detection is determined by the turn-on resistance turn-on resistance of the external control MOSFETs can be determined by the equation: DESIGN GUIDE
RON=VOIP/IT (IT is the overcurrent threshold current). For example, if the overcurrent Adjustment of Overcharge and
threshold current IT is designed to be 5A, the Overdischarge Delay Time
turn-on resistance of the external control Both the overcharge and overdischarge delay times default to 25mS and can be extended by aware that turn-on resistance of the MOSFET adding the external capacitors CTC and CTD, changes with temperature variation due to heat respectively. Increasing the capacitance value will dissipation. It changes with the voltage between increase the delay time. The relationship gate and source as well. (Turn-on resistance of a between capacitance of the external capacitors MOSFET increases as the voltage between gate resistance of the external MOSFET changes, the overcurrent threshold current will change release voltage and bleeding function. The relationship among Vrelease1,Vrelease2, R1, Suppressing the Ripple and Disturbance
from Charger
To suppress the ripple and disturbance from charger, connecting C1 to cell 1 and C2 to cell 2 Vrelease1 is Battery 1, real overcharge release Vrelease2 is Battery 2, real overcharge release Controlling the Charge Control MOSFET
R3, R4, R5 and NPN transistor Q1 are used to Therefore, resistance of R1 and R2 should not higher than 30Ω. Otherwise, overcharge release overcharge does not occur, no current flows out from OC pin and Q1 are turned off, then M2 is protection voltage and the charging current may turned on. When overcharge occurs, current oscillate. In addition, if overcharge protection flows out from OC pin and Q1 is turned on, which function occurs, AIC1802 will discharge the turns off M2 in turn. High resistance for R3, R4, overcharged cell and will stop bleeding function and R5 is recommended for reducing loading of even if the voltage is not equal to the other. The recommended resistance of R1 and R2 is from Latch-Up Protection at CS Pin
Effect of C3
R6 is used for latch-up protection when charger C3 has to be applied to the circuit. Because C3 is connected under overdischarge condition, and also for overstress protection when charger is overdischarge occurred. In addition, when the connected in reverse. The charge detection differential voltage between charger and battery function after overdischarge is possibly disabled by larger value of R6. Resistance of 1KΩ is protection function work, C3 will avoid battery pack from being charged even if the battery
Selection of R1 and R 2
voltage lower than 4V (To avoid battery pack from R1 and R2 are used to avoid large current flow through the battery pack under the situation of IC situation). The battery pack can be charged again resistance of R1 and R2 will affect overcharge PHYSICAL DIMENSIONS
SOP-8 (unit: mm)
1.Refer to JEDEC MS-012AA. 2.Dimension “D” does not include mold flash, protrusions or gate burrs. Mold flash, protrusion or gate burrs shall not exceed 6 mil per side. 3.Dimension “E” does not include inter-lead flash or protrusions. Inter-lead flash or protrusion shall not exceed 10 mil per side.
4.Controlling dimension is millimeter, converted inch dimensions Information provided by AIC is believed to be accurate and reliable. However, we cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AIC product; nor for any infringement of patents or other rights of third parties that may result from its use. We reserve the right to change the circuitry and specifications without notice. Life Support Policy: AIC does not authorize any AIC product for use in life support devices and/or systems. Life support devices or systems are devices or systems which, (I) are intended for surgical implant into the body or (ii) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.

Source: http://www.domko.ru/pdf/pdf/d/ds-1802g-01.pdf