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参数资料
| 型号： | TC7135CLIRT |
| 元件分类： | ADC |
| 英文描述： | 1-CH DUAL-SLOPE ADC, ACCESS, PQCC28 |
| 封装： | PLASTIC, LCC-28 |
| 文件页数： | 12/16页 |
| 文件大小： | 217K |
| 代理商： | TC7135CLIRT |
5
TC7135
4-1/2 DIGIT
ANALOG-TO-DIGITAL CONVERTER
TC7135-10 9/27/99
GENERAL THEORY OF OPERATION
(All Pin Designations Refer to 28-Pin DIP)
Dual-Slope Conversion Principles
The TC7135 is a dual-slope, integrating analog-to-
digital converter. An understanding of the dual-slope con-
version technique will aid in following detailed TC7135
operational theory.
The conventional dual-slope converter measurement
cycle has two distinct phases:
(1) Input signal integration
(2) Reference voltage integration (deintegration)
The input signal being converted is integrated for a fixed
time period, measured by counting clock pulses. An oppo-
site polarity constant reference voltage is then integrated
until the integrator output voltage returns to zero. The
reference integration time is directly proportional to the input
signal.
In a simple dual-slope converter, a complete conversion
requires the integrator output to "ramp-up" and "ramp-
down."
A simple mathematical equation relates the input signal,
reference voltage, and integration time:
For a constant VIN:
VIN = VR
.
Figure 4. Basic Dual-Slope Converter
Figure 3E. Integrator Output Zero Phase
The dual-slope converter accuracy is unrelated to the
integrating resistor and capacitor values, as long as they are
stable during a measurement cycle. Noise immunity is an
inherent benefit. Noise spikes are integrated, or averaged,
to zero during integration periods. Integrating ADCs are
immune to the large conversion errors that plague succes-
sive approximation converters in high-noise environments.
(See Figure 4.)
TC7135 Operational Theory
The TC7135 incorporates a system zero phase and
integrator output voltage zero phase to the normal two-
phase dual-slope measurement cycle. Reduced system
errors, fewer calibration steps, and a shorter overrange
recovery time result.
The TC7135 measurement cycle contains four phases:
(1) System zero
(2) Analog input signal integration
(3) Reference voltage integration
(4) Integrator output zero
Internal analog gate status for each phase is shown in
Table 1.
tRI
tSI
[]
where:
VR = Reference voltage
tSI = Signal integration time (fixed)
tRI = Reference voltage integration time (variable).
1VR tRI
RC
VIN(t) dt =
,
∫tSI
0
+
–
+
–
+
–
+ IN
IN
REF
ANALOG
COM
– IN
SWI
SWR
SWZ
SWI
SW1
SWZ
SWIZ
SWZ
INTEGRATOR
SWITCH CLOSED
SWITCH OPEN
SW RI
+
SWRI
–
COMPARATOR
TO
DIGITAL
SECTION
SW RI
+
SWRI
–
ANALOG
INPUT BUFFER
RINT
CINT
CREF
CSZ
+
–
REF
VOLTAGE
ANALOG
INPUT
SIGNAL
+
–
DISPLAY
SWITCH
DRIVER
CONTROL
LOGIC
INTEGRATOR
OUTPUT
CLOCK
COUNTER
POLARITY CONTROL
PHASE
CONTROL
VIN
VFULL SCALE
1/2 VFULL SCALE
VARIABLE
REFERENCE
INTEGRATE
TIME
FIXED
SIGNAL
INTEGRATE
TIME
INTEGRATOR
COMPARATOR
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| TC7135CBUTR | 1-CH DUAL-SLOPE ADC, ACCESS, PQFP64 |
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| TC7135CBURT | 1-CH DUAL-SLOPE ADC, ACCESS, PQFP64 |
| TC7135CLI | 1-CH DUAL-SLOPE ADC, PQCC28 |
| TC7135CBUTR | 1-CH DUAL-SLOPE ADC, PQFP64 |
相关代理商/技术参数 |
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|---|---|
| TC7135CPI | 功能描述:LED显示驱动器 4-1/2 Digit A/D BCD RoHS:否 制造商:Micrel 数位数量:5 片段数量: 安装风格:SMD/SMT 封装 / 箱体:PLCC-44 工作电源电压:4.75 V to 11 V 最大电源电流:10 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装:Tube |
| TC7135CPL | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:4-1/2 Digit A/D Converter |
| TC7136 | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:Low Power 3-1/2 Digit Analog-to-Digital Converter |
| TC7136A | 制造商:TELCOM 制造商全称:TelCom Semiconductor, Inc 功能描述:LOW POWER, 3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTERS |
| TC7136ACKW | 功能描述:LCD 驱动器 Low Power 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 |
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