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参数资料
| 型号： | TC7135CBURT |
| 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： | 2/16页 |
| 文件大小： | 217K |
| 代理商： | TC7135CBURT |
10
TC7135
4-1/2 DIGIT
ANALOG-TO-DIGITAL CONVERTER
TC7135-10 9/27/99
High-Speed Operation
The maximum conversion rate of most dual-slope ADCs
is limited by frequency response of the comparator. The
comparator in this circuit follows the integrator ramp with a
3
s delay, and at a clock frequency of 160kHz (6s period),
half of the first reference integrate clock period is lost in
delay. This means the meter reading will change from 0 to
1 with a 50
V input, 1 to 2 with 150V, 2 to 3 with 250V, etc.
This transition at midpoint is considered desirable by most
users; however, if clock frequency is increased appreciably
above 160kHz, the instrument will flash "1" on noise peaks
even when the input is shorted.
For many dedicated applications, where the input signal
is always of one polarity, comparator delay need not be a
limitation. Since nonlinearity and noise do not increase
substantially with frequency, clock rates up to ~1MHz may
be used. For a fixed clock frequency, the extra count (or
counts) caused by comparator delay will be constant and
can be digitally subtracted.
The clock frequency may be extended above 160kHz
without this error, however, by using a low value resistor in
series with the integrating capacitor. The effect of the
resistor is to introduce a small pedestal voltage onto the
integrator output at the beginning of reference-integrate
phase. By careful selection of the ratio between this resis-
tor and the integrating resistor (a few tens of ohms in the
recommended circuit), the comparator delay can be com-
pensated for and maximum clock frequency extended
by approximately a factor of 3. At higher frequencies, ring-
ing and second-order breaks will cause significant
nonlinearities during the first few counts of the instrument.
The minimum clock frequency is established by leakage
on the auto-zero and reference capacitors. With most de-
vices, measurement cycles as long as 10 seconds give no
measurable leakage error.
The clock used should be free from significant phase or
frequency jitter. Several suitable low-cost oscillators are
shown in the applications section. The multiplexed output
means if the display takes significant current from the logic
supply, the clock should have good PSRR.
Table 3. Conversion Rate vs. Clock Frequency
Conversion Rate
Clock
(Conv/Sec)
Frequency (kHz)
2.5
100
3.0
120
5.0
200
7.5
300
10.0
400
20.0
800
30.0
1200
Displays and Driver Circuits
TelCom Semiconductor manufactures three display de-
coder/driver circuits to interface the TC7135 to LCDs or LED
displays. Each driver has 28 outputs for driving four 7-
segment digit displays.
Device
Package
Description
TC7211AIPL
40-Pin Epoxy
4-Digit LCD Driver/Encoder
Several sources exist for LCDs and LED displays.
Display
Manufacturer
Address
Type
Hewlett Packard
640 Page Mill Road
LED
Components
Palo Alto, CA 94304
AND
720 Palomar Ave.
LCD and
Sunnyvale, CA 94086
LED
Epson America, Inc.
3415 Kanhi Kawa St.
LCD
Torrance, CA 90505
Table 2. Line Frequency Rejection
Oscillator Frequency
Frequency Rejected
(kHz)
(Hz)
300, 200, 150, 120,
60
100, 40, 33-1/3
250, 166-2/3,
50
125, 100
100
50, 60, 400
相关PDF资料 |
PDF描述 |
|---|---|
| TC7135CLI | 1-CH DUAL-SLOPE ADC, PQCC28 |
| TC7135CBUTR | 1-CH DUAL-SLOPE ADC, PQFP64 |
| TC7135CKW | 1-CH DUAL-SLOPE ADC, PQFP64 |
| TC7135CLITR | 1-CH DUAL-SLOPE ADC, PQCC28 |
| TC7135CPI | 1-CH DUAL-SLOPE ADC, PDIP28 |
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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