XB8608AJ ______________________________________ ________________________________________________________________________________ One Cell Lithium-ion/Polymer Battery Protection IC
GENERAL DESCRIPTION
The XB8608AJ Series product is a high integration solution for lithium-
ion/polymer battery protection.
XB8608AJ contains advanced power MOSFET, high-accuracy voltage detection circuits and delay circuits.
XB8608AJ is put into an SOP8
package and only one external component makes it an ideal solution in limited space of battery pack.
XB8608AJ has all the protection functions required in the battery application including overcharging, overdischarging, overcurrent and load short circuiting protection etc. The accurate overcharging detection voltage ensures safe and full utilization charging. The low standby current drains little current from the cell while in storage.
The device is not only targeted for digital cellular phones, but also for any other
Li-Ion and Li-Poly battery-powered information appliances requiring long-
term battery life.
FEATURES
·Protection of Charger Reverse Connection
·Protection of Battery Cell Reverse Connection
·Integrate Advanced Power MOSFET with Equivalent of 19.5mΩ R SS(ON)
·SOP8 Package
·Only One External Capacitor Required
·Over-temperature Protection ·Overcharge Current Protection ·Two-step Overcurrent Detection: -Overdischarge Current
-Load Short Circuiting
·Charger Detection Function
·0V Battery Charging Function
- Delay Times are generated inside ·High-accuracy Voltage Detection ·Low Current Consumption
- Operation Mode:3.5μA typ.
- Power-down Mode: 1.6μA typ. ·RoHS Compliant and Lead (Pb) Free
APPLICATIONS
One-Cell Lithium-ion Battery Pack
Lithium-Polymer Battery Pack
Figure 1. Typical Application Circuit
ORDERING INFORMATION
Note: “YW ” is manufacture date code, “Y ” means the year, “W ” means the week
PIN CONFIGURATION
Figure 2. PIN Configuration
PIN DESCRIPTION
ABSOLUTE MAXIMUM RATINGS
(Note: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability.)
ELECTRICAL CHARACTERISTICS
Typicals and limits appearing in normal type apply for T A= 25o C, unless otherwise specified
Figure 3. Functional Block Diagram FUNCTIONAL DESCRIPTION
The XB8608AJ monitors the voltage and current of a battery and protects it from being damaged due to overcharge voltage, overdischarge voltage, overdischarge current, and short circuit conditions by disconnecting the battery from the load or charger. These functions are required in order to operate the battery cell within specified limits.
The device requires only one external capacitor. The MOSFET is integrated and its R SS(ON) is as low as19.5mΩtypical.
Normal operating mode
If no exception condition is detected, charging and discharging can be carried out freely. This conditi
on is called the normal operating mode.
Overcharge Condition
When the battery voltage becomes higher than the overcharge detection voltage (V CU) during charging under normal condition
and the state continues for the overcharge detection delay time (t CU) or longer, the
XB8608AJ turns the charging control FET off to stop charging. This condition is called the overcharge condition. The overcharge condition is released in the following two cases:
1, When the battery voltage drops below the overcharge release voltage (V CL), the XB8608AJ turns the charging control FET on and returns to the normal condition.
2, When a load is connected and discharging starts, the XB8608AJ turns the charging control FET on and returns to the normal condition. The release mechanism is as follows: the discharging current flows through an internal parasitic diode of the charging FET immediately after a load is connected and discharging starts, and the VM pin voltage increases about 0.7 V (forward voltage of the diode) from the GND pin voltage momentarily. The
XB8608AJ detects this voltage and releases the overcharge condition. Consequently, in the case that the battery voltage is equal to or lower than the overcharge detection voltage (V CU), the
XB8608AJ returns to the normal condition immediately, but in the case the battery voltage is higher than the overcharge detection voltage (V CU),the chip does not return to the normal condition until the battery voltage drops below the overcharge detection voltage (V CU) even if the load is connected. In addition, if the VM pin voltage is equal to or lower than the overcurrent detection voltage when a load is connected and discharging starts, the chip does not return to the normal condition.
移动电池Remark If the battery is charged to a voltage higher than the overcharge detection voltage (V CU) and
the battery voltage does not drops below the overcharge detection voltage (V CU) even when a heavy load, which causes an overcurrent, is connected, the overcurrent do not work until the battery voltage drops below the overcharge detection voltage (V CU). Since an actual battery has, however, an internal impedance of several dozens of mΩ, and the battery voltage drops immediately after a heavy load which causes an overcurrent is connected, the overcurrent work. Detection of load short-circuiting works regardless of the battery voltage.
Overdischarge Condition
When the battery voltage drops below the overdischarge detection voltage (V DL) during discharging under normal condition and it continues for the overdischarge detection delay time (t DL) or longer, the
XB8608AJ turns the discharging control FET off and stops discharging. This condition is called overdischarge condition. After the discharging control FET is turned off, the VM pin is pulled up by the R VMD resistor
between VM and VDD in XB8608AJ. Meanwhile when VM is bigger than 1.5
V (typ.) (the load short-circuiting detection voltage), the current of the chip is reduced to the power-down current (I PDN). This condition is called power-down condition. The VM and VDD pins are shorted by the
R VMD resistor in the IC under the overdischarge and power-down conditions. The power-down condition is released when a charger is connected and the potential difference between VM and VDD becomes 1.3 V (typ.) or higher (load short-circuiting detection voltage). At this time, the FET is still off. When the battery voltage becomes the overdischarge detection voltage (V DL
) or higher (see note),
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