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| 型号： | TC7129CKW |
| 厂商： | Microchip Technology |
| 文件页数： | 11/28页 |
| 文件大小： | 0K |
| 描述： | IC ADC 4 1/2DGT LCD DVR 44-MQFP |
| 标准包装： | 96 |
| 显示器类型： | LCD |
| 配置： | 7 段显示 |
| 数字或字符： | A/D，4.5 位数字 |
| 电流 - 电源： | 800µA |
| 电源电压： | 6 V ~ 12 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 44-QFP |
| 供应商设备封装： | 44-PQFP（10x10） |
| 包装： | 托盘 |
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TC7129
V+
V+
1N4148
5 k Ω
39 k Ω
200 k Ω
19
24
TC7129
V DISP
20 k Ω
39 k Ω
2N2222
19
24
TC7129
V DISP
75 k Ω
36
DGND
23
V–
18 k Ω
36
DGND
23
V–
Figure 4-6:
Temperature Compensating Circuits.
4.5
RC Oscillator
4.6
Measuring Techniques
For applications in which 3-1/2 digit (100 μ V) resolution
is sufficient, an RC oscillator is adequate. A recom-
mended value for the capacitor is 51 pF. Other values
can be used as long as they are sufficiently larger than
the circuit parasitic capacitance. The resistor value is
Two important techniques are used in the TC7129:
successive integration and digital auto-zeroing.
Successive integration is a refinement to the traditional
dual-slope conversion technique.
calculated as:
4.7
Dual-Slope Conversion
EQUATION 4-1:
A dual-slope conversion has two basic phases: inte-
R=
0.45
Freq * C
grate and de-integrate. During the integrate phase, the
input signal is integrated for a fixed period of time; the
integrated voltage level is thus proportional to the input
For 120 kHz frequency and C = 51 pF, the calculated
value of R is 75 k Ω . The RC oscillator and the crystal
TC7129
voltage. During the de-integrate phase, the integrated
voltage is ramped down at a fixed slope, and a counter
counts the clock cycles until the integrator voltage
crosses zero. The count is a measurement of the time
to ramp the integrated voltage to zero and is, therefore,
proportional to the input voltage being measured. This
count can then be scaled and displayed as a measure-
ment of the input voltage. Figure 4-8 shows the phases
of the dual-slope conversion.
1
40
2
5 pF
120 kHz
270 k Ω
10 pF
Integrate
De-integrate
V+
V+
TC7129
Time
Zero
Crossing
1
40
2
75 k Ω
Figure 4-8:
Dual-Slope Conversion.
51 pF
The dual-slope method has a fundamental limitation.
The count can only stop on a clock cycle, so that mea-
Figure 4-7:
Oscillator Circuits.
surement accuracy is limited to the clock frequency. In
addition, a delay in the zero-crossing comparator can
add to the inaccuracy. Figure 4-9 shows these errors in
an actual measurement.
? 2006 Microchip Technology Inc.
DS21459D-page 11
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC7129CKW713 | 功能描述:LCD 驱动器 w/LCD Driver RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| TC7129CLW | 功能描述:LCD 驱动器 w/LCD Driver RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| TC7129CLW713 | 功能描述:LCD 驱动器 w/LCD Driver RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| TC7129CPL | 功能描述:LCD 驱动器 w/LCD Driver RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
| TC7129CPL713 | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:4-1/2 Digit Analog-to-Digital Converters with On-Chip LCD Drivers |
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