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參數(shù)資料
| 型號： | TC7135CLIRT |
| 元件分類： | ADC |
| 英文描述： | 1-CH DUAL-SLOPE ADC, ACCESS, PQCC28 |
| 封裝： | PLASTIC, LCC-28 |
| 文件頁數(shù)： | 12/16頁 |
| 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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|---|---|
| TC7135CPI | 功能描述:LED顯示驅(qū)動器 4-1/2 Digit A/D BCD RoHS:否 制造商:Micrel 數(shù)位數(shù)量:5 片段數(shù)量: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PLCC-44 工作電源電壓:4.75 V to 11 V 最大電源電流:10 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Tube |
| TC7135CPL | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:4-1/2 Digit A/D Converter |
| TC7136 | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:Low Power 3-1/2 Digit Analog-to-Digital Converter |
| TC7136A | 制造商:TELCOM 制造商全稱:TelCom Semiconductor, Inc 功能描述:LOW POWER, 3-1/2 DIGIT ANALOG-TO-DIGITAL CONVERTERS |
| TC7136ACKW | 功能描述:LCD 驅(qū)動器 Low Power RoHS:否 制造商:Maxim Integrated 數(shù)位數(shù)量:4.5 片段數(shù)量:30 最大時鐘頻率:19 KHz 工作電源電壓:3 V to 3.6 V 最大工作溫度:+ 85 C 最小工作溫度:- 20 C 封裝 / 箱體:PDIP-40 封裝:Tube |
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