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參數(shù)資料
| 型號(hào)： | TC850IJL |
| 廠商： | TelCom Semiconductor, Inc. |
| 英文描述： | 15-BIT, FAST-INTEGRATING CMOS ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 15位，快速整合過程CMOS模擬數(shù)字轉(zhuǎn)換器 |
| 文件頁數(shù)： | 5/14頁 |
| 文件大?。?/td> | 164K |
| 代理商： | TC850IJL |
3-81
TELCOM SEMICONDUCTOR, INC.
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Multiple-Slope Conversion Principles
One limitation of the dual-slope measurement tech-
nique is conversion speed. In a typical dual-slope method,
the auto-zero and integrate times are each one-half of the
deintegrate time. For a 15-bit conversion, 2
14
+ 2
14
+ 2
15
(65,536) clock pulses are required for auto-zero, integrate,
and deintegrate phases, respectively. The large number of
clock cycles effectively limits the conversion rate to about
2.5 conversions per second, when a typical analog CMOS
fabrication process is used.
The TC850 uses a multiple-slope conversion technique
to increase conversion speed (Figure 2B). This technique
makes use of a two-slope deintegration phase and permits
15-bit resolution up to 40 conversions per second.
During the TC850's deintegration phase, the integration
capacitor is rapidly discharged to yield a resolution of 9 bits.
At this point, some charge will remain on the capacitor. This
remaining charge is then slowly deintegrated, producing an
THEORY OF OPERATION
The TC850 is a multiple-slope, integrating analog-to-
digital converter (ADC). The multiple-slope conversion pro-
cess, combined with chopper-stabilized amplifiers, results
in a significant increase in ADC speed, while maintaining
very high resolution and accuracy.
Dual-Slope Conversion Principles
The conventional dual-slope converter measurement
cycle (shown in Figure 2A) 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, complete conversion
requires the integrator output to "ramp-up" and "ramp-
down." Most dual-slope converters add a third phase, auto-
zero. During auto-zero, offset voltages of the input buffer,
integrator, and comparator are nulled, thereby eliminating
the need for zero-offset adjustments.
Dual-slope converter accuracy is unrelated to the inte-
grating resistor and capacitor values, as long as they are
stable during a measurement cycle. By converting the
unknown analog input voltage into an easily-measured
function of time, the dual-slope converter reduces the need
for expensive, precision passive components.
Noise immunity is an inherent benefit of the integrating
conversion method. Noise spikes are integrated, or aver-
aged, to zero during the integration period. Integrating ADCs
are immune to the large conversion errors that plague
successive approximation converters in high-noise environ-
ments.
A simple mathematical equation relates the input signal,
reference voltage, and integration time:
∫
0
where: V
R
= Reference voltage
t
SI
= Signal integration time (fixed)
t
RI
= Reference voltage integration time (variable).
Figure 1. Standard Circuit Configuration
BUSY
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
CS
CE
WR
RD
CONT/DEMAND
OVR/POL
L/H
V
DD
V
SS
16
8
9
10
11
12
13
14
15
1
2
3
4
5
6
7
17
TC850
0.01
μ
F INPUT
+1.6384V
+0.0265V
100 M
120 M
1
μ
F
*
1
μ
F
*
0.1
μ
F
0.1
μ
F
0.1
μ
F
0.1
μ
F
0.1
μ
F
0.1
μ
F
IN
+
IN
–
COMMON
REF1
REF2
REF–
C+
+
C–
+
+
BUFFER
OSC1
OSC2
INTIN
INTOUT
CINTB
CINTA
–
CREF2
RINT
CINT
CBUFACBUFB
27
COMP
TEST
NC
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21
28
29
26
19
23
24
25
35
34
37
38
36
33
39
30
31
61.44 kHz
20
22
40
–5V
+5V
DGND
32
**
**
NOTES:
Unless otherwise specified, all 0.1
μ
F capacitors are film dielectric.
Ceramic capacitors are not recommended.
NC = No internal capacitors
*Polypropylene capacitors.
** 100pF Mica capacitors.
t
SI
V
IN
(t) dt = ,
V
t
RC
1
RC
TC850
15-BIT, FAST-INTEGRATING CMOS
ANALOG-TO-DIGITAL CONVERTER
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| TC850CLW | 15-Bit, Fast Integrating CMOS A/D Converter |
| TC850CPL | 15-Bit, Fast Integrating CMOS A/D Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TC850ILW | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 16 Bit Hi Speed A/D RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| TC850ILW713 | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 16 Bit Hi Speed A/D RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32 |
| TC8521AM | 制造商:TOSHIBA 制造商全稱:Toshiba Semiconductor 功能描述:REAL TIME CLOCK ケ |
| TC8521AP | 制造商:TOSHIBA 制造商全稱:Toshiba Semiconductor 功能描述:REAL TIME CLOCK ケ |
| TC8566AF | 制造商:TOSHIBA 制造商全稱:Toshiba Semiconductor 功能描述:FLOPPY DISK CONTROLLER |
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