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参数资料
| 型号： | TC7129CLW |
| 元件分类： | ADC |
| 英文描述： | 1-CH DUAL-SLOPE ADC, ACCESS, PQCC44 |
| 封装： | PLASTIC, LCC-44 |
| 文件页数： | 15/17页 |
| 文件大小： | 185K |
| 代理商： | TC7129CLW |
7
TC7129
4-1/2 DIGIT ANALOG-TO-DIGITAL
CONVERTER WITH ON-CHIP LCD DRIVERS
Integrating Capacitor (CINT)
The charge stored in the integrating capacitor during
the integrate phase is directly proportional to the input
voltage. The primary selection criterion for CINT is to choose
a value that gives the highest voltage swing while remain-
ing within the high-linearity portion of the integrator output
range. An integrator swing of 2V is the recommended
value. The capacitor value can be calculated from the
equation:
CINT =
,
where tINT is the integration time.
Using the values derived above (assuming 60Hz
operation), the equation becomes:
CINT =
= 0.1
F.
The capacitor should have low dielectric absorption to
ensure good integration linearity. Polypropylene and Teflon
capacitors are usually suitable. A good measurement of the
dielectric absorption is to connect the reference capacitor
across the inputs by connecting:
Pin to Pin
20
→ 33
(CREF+ to IN HI)
30
→ 32
(CREF– to IN LO)
A reading between 10,000 and 9998 is acceptable;
anything lower indicates unacceptably high dielectric ab-
sorption.
Reference Capacitor (CREF)
The reference capacitor stores the reference voltage
during several phases of the measurement cycle. Low
leakage is the primary selection criterion for this component.
The value must be high enough to offset the effect of stray
capacitance at the capacitor terminals. A value of at least
1
F is recommended.
Voltage Reference (DREF, RREF, RBIAS, CRF)
A TC04 band-gap reference provides a high-stability
voltage reference of 1.25V. The reference potentiometer
(RREF) provides an adjustment for adjusting the reference
voltage; any value above 20 k
is adequate. The bias
resistor (RBIAS) limits the current through DREF to less than
150
A. The reference filter capacitor (CRF) forms an RC
filter with RBIAS to help eliminate noise.
Input filter (RIF, CIF)
For added stability, an RC input noise filter is usually
included in the circuit. The input filter resistor value should
not exceed 100k
. A typical RC time constant value is
16.7msec to help reject line-frequency noise. The input filter
capacitor should have low leakage for a high-impedance
input.
Battery
The typical circuit uses a 9V battery as a power source.
Any value between 6V and 12V can be used. For operation
from batteries with voltages lower than 6V and for operation
from power supplies, see "Powering the TC7129."
SPECIAL APPLICATIONS
The TC7129 as a Replacement Part
The TC7129 is a direct pin-for-pin replacement part for
the ICL7129. Note, however, that part requires a capacitor
and resistor between pins 26 and 28 for phase compensa-
tion. Since the TC7129 uses internal phase compensation,
these parts are not required and, in fact, must be removed
from the circuit for stable operation.
Powering the TC7129
While the most common power source for the TC7129
is a 9V battery, there are other possibilities. Some of the
more common ones are explained below.
16.7msec x 13.3
A
2V
tINT x IINT
VSWING
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| TC7135C/PI | 1-CH 4-BIT DUAL-SLOPE ADC, PARALLEL ACCESS, PDIP28 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| TC7129IJL713 | 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 |
| TC7129IKW713 | 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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