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參數(shù)資料
| 型號： | MXB7843EUE |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | ADC |
| 英文描述： | 2.375V to 5.25V, 4-Wire Touch-Screen |
| 中文描述： | 2-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, SERIAL ACCESS, PDSO16 |
| 封裝： | 4.40 MM, MO-153AB, TSSOP-16 |
| 文件頁數(shù)： | 13/21頁 |
| 文件大?。?/td> | 508K |
| 代理商： | MXB7843EUE |
Digital Interface
Initialization After Power-Up and Starting a
Conversion
The digital interface consists of three inputs, DIN, DCLK,
CS
, and one output, DOUT. A logic-high on
CS
disables
the MXB7843 digital interface and places DOUT in a
high-impedance state. Pulling
CS
low enables the
MXB7843 digital interface.
Start a conversion by clocking a control byte into DIN
(Table 3) with
CS
low. Each rising edge on DCLK
clocks a bit from DIN into the MXB7843
’
s internal shift
register. After
CS
falls, the first arriving logic 1 bit
defines the control byte
’
s START bit. Until the START bit
arrives, any number of logic 0 bits can be clocked into
DIN with no effect.
The MXB7843 is compatible with SPI/QSPI/MICROWIRE
devices. For SPI, select the correct clock polarity and
sampling edge in the SPI control registers of the micro-
controller: set CPOL = 0 and CPHA = 0. MICROWIRE,
SPI, and QSPI all transmit a byte and receive a byte at
the same time. The simplest software interface requires
only three 8-bit transfers to perform a conversion (one 8-
bit transfer to configure the ADC, and two more 8-bit
transfers to read the conversion result) (Figure 7).
Simple Software Interface
Make sure the CPU
’
s serial interface runs in master
mode so the CPU generates the serial clock. Choose a
clock frequency from 500kHz to 2MHz:
1) Set up the control byte and call it TB. TB should be
in the format: 1XXXXXXX binary, where X denotes
the particular channel, selected conversion mode,
and power mode (Tables 3, 4).
2) Use a general-purpose I/O line on the CPU to pull
CS
low.
3) Transmit TB and simultaneously receive a byte; call
it RB1.
4) Transmit a byte of all zeros ($00 hex) and simultane-
ously receive byte RB2.
5) Transmit a byte of all zeros ($00 hex) and simultane-
ously receive byte RB3.
6) Pull
CS
high.
Figure 7 shows the timing for this sequence. Bytes RB2
and RB3 contain the result of the conversion, padded
by four trailing zeros. The total conversion time is a func-
tion of the serial-clock frequency and the amount of idle
timing between 8-bit transfers.
Digital Output
The MXB7843 outputs data in straight binary format
(Figure 10). Data is clocked out on the falling edge of
the DCLK, MSB first.
Serial Clock
The external clock not only shifts data in and out, but it
also drives the analog-to-digital conversion steps.
BUSY pulses high for one clock period after the last bit
of the control byte. Successive-approximation bit deci-
sions are made and appear at DOUT on each of the
next 12 DCLK falling edges. BUSY and DOUT go into a
high-impedance state when
CS
goes high.
The conversion must complete in 500μs or less; if not,
droop on the sample-and-hold capacitors can degrade
conversion results.
Data Framing
The falling edge of
CS
does not start a conversion. The
first logic high clocked into DIN is interpreted as a start
bit and defines the first bit of the control byte. A conver-
sion starts on DCLK
’
s falling edge, after the eighth bit
of the control byte is clocked into DIN.
The first logic 1 clocked into DIN after bit 6 of a conver-
sion in progress is clocked onto the DOUT pin and is
treated as a START bit (Figure 8).
Once a start bit has been recognized, the current con-
version must be completed.
The fastest the MXB7843 can run with
CS
held continu-
ously low is 15 clock conversions. Figure 8 shows the
serial-interface timing necessary to perform a conver-
sion every 15 DCLK cycles. If
CS
is connected low and
DCLK is continuous, guarantee a start bit by first clock-
ing in 16 zeros.
Most microcontrollers (μCs) require that data transfers
occur in multiples of eight DCLK cycles; 16 clocks per
conversion is typically the fastest that a μC can drive the
MXB7843. Figure 9 shows the serial-interface timing nec-
essary to perform a conversion every 16 DCLK cycles.
8-Bit Conversion
The MXB7843 provides an 8-bit conversion mode
selected by setting the MODE bit in the control byte
high. In the 8-bit mode, conversions complete four
clock cycles earlier than in the 12-bit output mode,
resulting in 25% faster throughput. This can be used in
conjunction with serial interfaces that provide 12-bit
transfers, or two conversions could be accomplished
with three 8-bit transfers. Not only does this shorten each
conversion by 4 bits, but each conversion can also
M
2.375V to 5.25V, 4-Wire Touch-Screen
Controller
______________________________________________________________________________________
13
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相關代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MXB7843EUE+ | 功能描述:觸摸屏轉(zhuǎn)換器和控制器 2.375-5.25V 4-Wire Touch-Screen Ctlr RoHS:否 制造商:Microchip Technology 類型:Resistive Touch Controllers 輸入類型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 電源電壓:2.5 V to 5.25 V 電源電流:17 mA 工作溫度:- 40 C to + 85 C 封裝 / 箱體:SSOP-20 |
| MXB7843EUE+T | 功能描述:觸摸屏轉(zhuǎn)換器和控制器 2.375-5.25V 4-Wire Touch-Screen Ctlr RoHS:否 制造商:Microchip Technology 類型:Resistive Touch Controllers 輸入類型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 電源電壓:2.5 V to 5.25 V 電源電流:17 mA 工作溫度:- 40 C to + 85 C 封裝 / 箱體:SSOP-20 |
| MXB7843EUE-T | 功能描述:觸摸屏轉(zhuǎn)換器和控制器 RoHS:否 制造商:Microchip Technology 類型:Resistive Touch Controllers 輸入類型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 電源電壓:2.5 V to 5.25 V 電源電流:17 mA 工作溫度:- 40 C to + 85 C 封裝 / 箱體:SSOP-20 |
| MXB7846 | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:2.375V to 5.25V, 4-Wire Touch-Screen Controller with Internal Reference and Temperature Sensor |
| MXB7846EEE | 功能描述:觸摸屏轉(zhuǎn)換器和控制器 RoHS:否 制造商:Microchip Technology 類型:Resistive Touch Controllers 輸入類型:3 Key 數(shù)據(jù)速率:140 SPS 分辨率:10 bit 接口類型:4-Wire, 5-Wire, 8-Wire, I2C, SPI 電源電壓:2.5 V to 5.25 V 電源電流:17 mA 工作溫度:- 40 C to + 85 C 封裝 / 箱體:SSOP-20 |
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