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參數(shù)資料
| 型號： | TC3401EPE |
| 元件分類： | ADC |
| 英文描述： | 2-CH 16-BIT DELTA-SIGMA ADC, SERIAL ACCESS, PDIP16 |
| 封裝： | PLASTIC, DIP-16 |
| 文件頁數(shù)： | 8/12頁 |
| 文件大?。?/td> | 70K |
| 代理商： | TC3401EPE |
5
TC3401
16-BIT LOW COST, LOW POWER
∑ – A/D CONVERTER
TC3401-1
10/14/99
GENERAL THEORY OF OPERATION
The TC3401 has a 16-bit sigma-delta A/D converter. It
has two differential inputs, an analog multiplexer, a VDD
monitor with reset generator, and an early warning power fail
detector. The detailed description of the key components of
the TC3401 is outlined below. (Also refer to the
A/D Opera-
tional Flowchart on page 10 and the Timing Diagrams in
Figures 2 through 5).
A/D Converter Operation
When the TC3401 is not converting, it is in sleep mode
with both the SCLK and SDAT lines high. An A/D conversion
is initiated by a high to low transition on the SCLK line at
which time the internal clock of the TC3401 is started and the
address value (ADDR) is internally latched. The address
value steers the analog multiplexer to select the input
channel to be converted. Each additional high to low transi-
tion of SCLK (following the initial SCLK falling edge) and
during the time interval t4 will decrement the conversion
accuracy by one bit and reduce the conversion time by one
half. The time interval t4 is referred to as the resolution
reduction window. The minimum conversion resolution is 10
bits so any more than 6 SCLK transitions during t4 will be
ignored.
After each high to low transition of SCLK, in the t4
interval, the SDAT output is driven high by the TC3401 to
acknowledge that the conversion has been decremented.
When the SCLK returns high or the t4 interval ends, the
SDAT line returns low (see Figure 2). When the conversion
is complete SDAT is driven high. The 3401 now enters sleep
mode and the conversion value can be read as a serial data
word on the SDAT line.
Reading the Data Word
After the conversion is complete and SDAT goes high,
the conversion value can be clocked serially onto the SDAT
line by high to low transitions of the SCLK. The data word is
in two’s compliment format with the sign bit clocked onto the
SDAT line first followed by the MSB and ending in the LSB.
For a 16 bit conversion the data word would consist of a sign
bit follwed by 15 magnitude bits, Table 1 shows the data
word versus input voltage for a16 bit conversion. Note that
the full scale input voltage range is
±(2 REFIN– 1LSB). When
REFOUT of the TC3401 is fed back directly to the REFIN
pin then REFIN is typically 1.193V and an LSB is 75V for a
16 bit conversion.
Figure 4 shows typical SCLK and SDAT waveforms for
16, 12 and 10 bit conversions. Note that any complete
convert and read cycle requires 17 netgative edge clock
pulses. The first is the convert command. Then, up to six of
these can occur in the resolution reduction window, t4, to
decrement accuracy. The remaining pulses clock out the
conversion data word.
Table 1. Data Conversion Word vs. Voltage Input
(REFIN = 1.193V)
Data Word
INn+ – INn– (Volts)
0111 1111 1111 1111
2.4699246 (Positive Full Scale)
0000 0000 0000 0001
75.4 E – 6
0000 0000 0000 0000
0
1111 1111 1111 1111
–75.4 E – 6
1000 0000 0000 0001
–2.4699246 (Negative Full Scale)
1000 0000 0000 0000
Reserved Code
The SCLK input has a filter which rejects any positive or
negative pulse of width less than 50nsec to reduce noise.
The rejection width of this pulse can vary between 50nsec
and 750nsec depending on processing parameters and
supply voltage.
Figure 3 shows a truth table for determining the mode of
operation for the TC3401 part by recording the value of
SDAT for SCLK in a high, then low, then high state. For
example, if SCLK goes through a 1-0-1 transition and the
corresponding values of SDAT are 1-1-0, then the SCLK
falling edge started a new data conversion. A 0-1-0 for SDAT
would have indicated a resolution reduction had occurred.
This is useful if the microcontroller has a watchdog reset or
otherwise loses track of where the TC3401 part is in the
conversion and data readout sequence. The microcontroller
can simply transition SCLK until it “finds” a Start Conversion
condition.
VDD Monitor
The TC3401 RESET output is high provided the voltage
at VTH is greater than the internal voltage refererence. This
reference is approximately the same value as the voltage
appearing at REFOUT. When VTH is less than the internal
reference, RESET is pulled low. When VTH rises above the
internal reference voltage again RESET is held low for the
reset active timeout period, t9, before being released high.
The RESET output is guaranteed to be valid for VDD = 1.3V
to 5.5V.
When used to generate a power-on or brown-out reset
an external resistor network is required to divide the appro-
priate VDD threshold down to 1.23V at the VTH input
(see Figure 1). For example, to generate a POR for a VDD
at 3V-10%, then the values of R1 and R2 should be 137k
and 115k
respectively.
Since RESET is an open drain it can be wired-OR’ed
with another open drain or external switch if desired.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| TC3401VPE | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 16-Bit Sigma-Delta 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 |
| TC3401VQR | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 16-Bit Sigma-Delta 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 |
| TC3401VQRTR | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 16-Bit Sigma-Delta 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 |
| TC3402 | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:+1.8 Low Power, Quad Input, 16-Bit Sigma-Delta A/D Converter |
| TC3402VPE | 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 16-Bit Sigma-Delta 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 |
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