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参数资料
| 型号： | TC7135CBUTR |
| 元件分类： | ADC |
| 英文描述： | 1-CH DUAL-SLOPE ADC, ACCESS, PQFP64 |
| 封装： | PLASTIC, QFP-64 |
| 文件页数： | 16/16页 |
| 文件大小： | 217K |
| 代理商： | TC7135CBUTR |
9
TC7135
4-1/2 DIGIT
ANALOG-TO-DIGITAL CONVERTER
TC7135-10 9/27/99
POLARITY Output
A positive input is registered by a logic "1" polarity signal.
The POLARITY output (pin 23) is valid at the beginning of
reference integrate and remains valid until determined dur-
ing the next conversion.
The POLARITY bit is valid even for a zero reading.
Signals less than the converter's LSB will have the signal
polarity determined correctly. This is useful in null applica-
tions.
Digit Drive Outputs
Digit drive outputs are positive-going signals. Their scan
sequence is D5, D4, D3, D2 and D1 (pins 12, 17, 18, 19 and
20, respectively). All positive signals are 200 clock pulses
wide, except D5, which is 201 clock pulses.
All five digits are continuously scanned, unless an
overrange condition occurs. In an overrange condition, all
digit drives are held low from the final STROBE pulse until
the beginning of the next reference-integrate phase. The
scanning sequence is then repeated, providing a blinking
visual display.
BCD Data Outputs
The binary coded decimal (BCD) outputs, B8, B4, B2 and
B1 (pins 16, 15, 14 and 13, respectively) are positive true-
logic signals. They become active simultaneously with digit
drive signals. In an overrange condition, all data bits are
logic "0".
APPLICATIONS INFORMATION
Component Value Selection
Integrating Resistor
The integrating resistor (RINT) is determined by the full-
scale input voltage and output current of the buffer used to
charge the integrator capacitor (CINT). Both the buffer ampli-
fier and the integrator have a Class A output stage, with
100
A of quiescent current. A 20A drive current gives
negligible linearity errors. Values of 5
A to 40A give good
results. The exact value of RINT for a 20A current is easily
calculated:
RINT =
.
Full-scale voltage
20
A
Integrating Capacitor
The product of RINT and CINT should be selected to give
the maximum voltage swing to ensure tolerance buildup will
not saturate integrator swing (approximately 0.3V from
either supply). For
±5V supplies, and analog common tied to
supply ground, a
±3.5V to ±4V full-scale integrator swing is
CINT =
=
.
[10,000 x clock period] x IINT
Integrator output voltage swing
(10,000) (clock period) (20
A)
Integrator output voltage swing
A very important characteristic of the CINT is that it has
low dielectric absorption to prevent roll-over or ratiometric
errors. A good test for dielectric absorption is to use the
capacitor with the input tied to the reference. This ratiometric
condition should read half-scale 0.9999. Any deviation is
probably due to dielectric absorption. Polypropylene
capacitors give undetectable errors at reasonable cost.
Polystyrene and polycarbonate capacitors may also be
used in less critical applications.
Auto-Zero and Reference Capacitors
The size of the auto-zero capacitor (CAZ) has some
influence on system noise. A large capacitor reduces noise.
The reference capacitor (CREF) should be large enough
such that stray capacitance from its nodes to ground is
negligible.
The dielectric absorption of CREF and CAZ is only impor-
tant at power-on, or when the circuit is recovering from an
overload. Smaller or cheaper capacitors can be used if
accurate readings are not required during the first few
seconds of recovery.
Reference Voltage
The analog input required to generate a full-scale output
is VIN = 2 VREF.
The stability of the reference voltage is a major factor in
overall absolute accuracy of the converter. Therefore, it is
recommended that high-quality references be used where
high-accuracy, absolute measurements are being made.
Suitable references are:
Part Type
Manufacturer
TC04
TelCom Semiconductor
TC05
TelCom Semiconductor
Conversion Timing
Line Frequency Rejection
A signal-integration period at a multiple of the 60Hz line
frequency will maximize 60Hz "line noise" rejection.
A 100kHz clock frequency will reject 50Hz, 60Hz and
400Hz noise, corresponding to 2.5 readings per second.
adequate. A 0.10
F to 0.47F is recommended. In general,
the value of CINT is given by:
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC7135CKW | 制造商:MICROCHIP 制造商全称:Microchip Technology 功能描述:4-1/2 Digit A/D Converter |
| TC7135CLI | 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 |
| TC7135CLI713 | 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 |
| 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 |
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