Features

#10148; Multi -function charge and discharge meter

#10148; Analyze the signal of less than 12.5μV

#10148; Excisible

#10148; 1024 -bit nvram of 128 X 8

#10148; internal temperature sensor used for self -power release

-sleep: lt; 10 Wei'an

[[

General description

is a low -cost charging and discharge meter peripheral device, which is encapsulated with 8 -needle TSSOP or SOIC. It works with the smart host controller to provide charging state information for rechargeable batteries. BQ2018 measures the voltage drop of the low -value series sensor between the negative polar end of the battery and the grounding of the battery pack. The intelligent main controller uses the cumulative counting in charging, discharge, and self -discharge registers to determine the charging status information of the battery. To improve accuracy, the offset counting register can be used. The main controller of the system is responsible for the maintenance of the register, and the recharge/out and self -discharge registers are reset/out and the self -discharge registers as needed.

BQ2018 also has a 128 -byte NVRAM register. The upper 13 bytes of NVRAM contain capacity monitoring and status information. The RBI input is operated by an external power supply (such as a capacitor or series battery in the battery pack). It is not easy for the register when the battery is short -circuit or the battery charging state is not enough to operate the BQ2018. In this mode, the register backup current is less than 100NA.

BQ2018 is packaged in 8 -needle Tssop or SOIC, which is small enough. It can be installed in the gap between the two Asize units, or it can be installed in the width of the prism unit.

The name of the tube foot

function description General operation

The host can use the BQ2018 internal counter and timer Measure the charging status of the battery, estimate the self -discharge, and calculate the average charging and discharge current that enters and leave the rechargeable battery. BQ2018 requires an external host system to perform all registration maintenance. The system host uses the information provided by BQ2018 to determine the charging status of the batteryIt is estimated that self -discharge and calculate the average charging power current. During the packaging and storage, the use of internal temperature sensors doubles the self -discharge counting rate of 25 ° C or more per 10 °.

In order to reduce costs, low -cost external FET and REG tube feet can be used to obtain the power of BQ2018. The working current of BQ2018 is less than 80 Weire. When the HDQ line keeps a low voltage of more than 10 seconds and VSR (VSR+VOS, of which VSR is a voltage drop between SR1 and SR2, VOS is offset voltage) lower than the minimum level of programming (wake -up at high Z), BQ2018 enters enters entering lt; 10 Weian's sleep mode, all operations are suspended. HDQ conversion high re -initialization BQ2018.

The register can be used to store the offset of calculation and allows the current calibration. The offset removal register is written by BQ2018 during the packaging and assembly, which can be adjusted by the host system to adjust the current measurement value. By increasing or reduced the offset value stored in OFR, a real charging meter can be largely calculated.

FIG. 1 shows the box diagram of BQ2018, which summarizes the operating status of BQ2018.

REG output

As long as VCC is limited to 2.8 to 5.5V, BQ2018 can operate directly from three or four nickel chemical batteries or a single lithium ion battery. In order to meet the power supply requirements of BQ2018, the REG output is used to regulate the external low threshold N-JFET. Using this field effect Crystal tube can make a micro -power VCC source for BQ2018 cheaply.

RBI input pin with storage capacitors or external power supply, when VCC drops to below 2.4V Provide spare voltage for internal RAM. In this mode, the maximum discharge current is 100NA. When the power supply is higher than 2.4V, the BQ2018 outputs VCC on the RBI, so the diode isolates the external power supply.

Charging and discharge meter operation

Table 2 shows the main counter and register of BQ2018. BQ2018 adds charging and discharge counts to the two main count registers, and the discharge count register (DCR) and the charging counter register (CCR). BQ2018 generates charging meter through the voltage difference between the low -value resistance between the negative extreme of the battery pack and the negative terminal of the battery. DCR or CCR counts depends on signals between SR1 and SR2.

During the discharge process, DCR and discharge time counter (DTC) activation. If VSR1 is less than VSR2, it means discharge, the DCR is count at a rate of 12.5 slightly per hour, and DTC counts at a rate of 1 count /0.8789 seconds (4096 per hour). For example, -100mv signal generates 8 per hour per hour000 DCR count and 4096 DTC counts. The amount removed from the battery can be obtained by simple calculations.

During the charging period, CCR and charging time counter (CTC) are in a state of activity. If VSR1 is greater than VSR2, it means charging, then CCR is counting at a rate of 12.5 slightly per hour, and CTC counts at a rate of 1

count/0.8789 seconds. For example, the+100MV signal Pro decreases 8,000 CCR counts and 4096 CTC counting hours of battery. It is easy to calculate.

DTC and CTC are 16 -bit registers and rolled after FFFFH. If a flip occurs, the corresponding position in the mode/WOE register is set, and the counter will then increase at 1/256 at a normal rate (16 count/hour).