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參數(shù)資料
| 型號(hào)： | bq2945 |
| 廠商： | Benchmark Technology Group |
| 英文描述： | Gas Gauge IC with SMBus Interface(Gas Gauge芯片（帶SMBus 接口）) |
| 中文描述： | 氣體計(jì)IC，帶有SMBus接口（電量監(jiān)測計(jì)芯片（帶的SMBus接口）） |
| 文件頁數(shù)： | 10/32頁 |
| 文件大?。?/td> | 256K |
| 代理商： | BQ2945 |
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In absolute mode, each segment represents a fixed
amount of charge, 20% of the DesignCapacity. As the
battery wears out over time, it is possible for the FCC to
be below the design capacity.
LEDs may not turn on in absolute mode, representing
the reduction in the actual battery capacity.
In this case, all of the
When DISP is tied to V
CC
, the LED
1-5
outputs are inac-
tive. When DISP is left floating, the display becomes ac-
tive whenever the bq2945 detects a charge rate of
100mA or more. When pulled low, the segment outputs
become active immediately for a period of approximately
4 seconds. The DISP pin must be returned to float or
V
CC
to reactivate the display.
LED
1
blinks at a 4Hz rate whenever V
SB
has been de-
tected to be below EDV1 (EDV1 = 1), indicating a low-
battery condition. V
SB
below EDVF (EDVF = 1) disables
the display output.
Microregulator
The bq2945 can operate directly from three nickel chem-
istry cells. To facilitate the power supply requirements
of the bq2945, an REF output is provided to regulate an
external low-threshold n-FET. A micropower source for
the bq2945 can be inexpensively built using a 2N7002 or
BSS138 FET and an external resistor.
The value of R11 depends on the battery pack’s nominal
voltage.
(See Figure 1.)
Communicating with the bq2945
The bq2945 includes a simple two-pin (SMBC and
SMBD) bi-directional serial data interface. A host proc-
essor uses the interface to access various bq2945 regis-
ters; see Table 4. This method allows battery character-
istics to be monitored easily. The open-drain SMBD and
SMBC pins on the bq2945 are pulled up by the host sys-
tem, or may be connected to V
SS
, if the serial interface is
not used.
The interface uses a command-based protocol, where the
host processor sends the battery address and an eight-
bit command byte to the bq2945. The command directs
the bq2945 to either store the next data received to a
register specified by the command byte or output the
data specified by the command byte.
bq2945 Data Protocols
The host system, acting in the role of a Bus master, uses
the read word and write word protocols to communicate
integer data with the bq2945. (See Figure 3.)
Host-to-bq2945 Message Protocol
The Bus Host communicates with the bq2945 using one
of three protocols:
Read word
Write word
Read block
The particular protocol used is a function of the com-
mand.The protocols used are shown in Figure 3.
Host-to-bq2945Messages(seeTable4)
ManufacturerAccess() (0x00)
This function is used to control CP
1
and CP
2
. (See Table
7.)
10
bq2945
Symbol
V
OS
Parameter
Typical
±
75
Maximum
±
150
Units
μ
V
Notes
Offset referred to V
SR
Integrated non-linearity
error
Integrated non-
repeatability error
DISP = V
CC
.
Add 0.1% per °C above or below 25°C
and 1% per volt above or below 4.25V.
Measurement repeatability given
similar operating conditions.
INL
±
1
±
4
%
INR
±
0.5
±
1
%
Table 3. bq2945 Current-Sensing Errors
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| BQ294502 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Overvoltage Protection for 2-Series and 3-Series Cell Li-Ion Batteries |
| BQ294502DRVR | 功能描述:電池管理 Overvltg Prot Device RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| BQ294502DRVT | 功能描述:電池管理 Overvltg Prot Device RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| BQ294502EVM-033 | 功能描述:電源管理IC開發(fā)工具 bq294502 Eval Mod RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| BQ294504 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Overvoltage Protection for 2-Series and 3-Series Cell Li-Ion Batteries |
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