參數(shù)資料
型號: MAX147ACAP
廠商: MAXIM INTEGRATED PRODUCTS INC
元件分類: ADC
英文描述: +2.7Low-Power, 8-Channel, Serial 12-Bit ADCs
中文描述: 8-CH 12-BIT SUCCESSIVE APPROXIMATION ADC, SERIAL ACCESS, PDSO20
封裝: SSOP-20
文件頁數(shù): 12/24頁
文件大?。?/td> 198K
代理商: MAX147ACAP
M
+2.7V, Low-Power, 8-Channel,
S erial 12-Bit ADCs
12
______________________________________________________________________________________
SSTRB
CS
SCLK
DIN
DOUT
1
4
8
12
16
20
24
START
SEL2 SEL1 SEL0
UNI/
BIP
DIF
PD1
PD0
B11
B10
B9
B8
B7
B6
B5
B4
B3
B2
B1
B0
ACQUISITION
1.5
μ
s
(f
SCLK
= 2MHz)
IDLE
FILLED WITH
ZEROS
IDLE
CONVERSION
t
ACQ
A/D STATE
RB1
RB2
RB3
Figure 6. 24-Clock External Clock Mode Conversion Timing (Microwire and SPI Compatible, QSPI Compatible with f
SCLK
2MHz)
How to S tart a Conversion
Start a conversion by clocking a control byte into DIN.
With
CS
low, each rising edge on SCLK clocks a bit from
DIN into the MAX146/MAX147’s internal shift register.
After
CS
falls, the first arriving logic “1” bit defines the
control byte’s MSB. Until this first “start” bit arrives, any
number of logic “0” bits can be clocked into DIN with no
effect. Table 1 shows the control-byte format.
The MAX146/MAX147 are compatible with SPI /
QSPI and Microwire devices. For SPI, select the
correct clock polarity and sampling edge in the SPI
control registers: set CPOL = 0 and CPHA = 0. Micro-
wire, SPI, and QSPI all transmit a byte and receive a
byte at the same time. Using the Typical Operating
Circuit, 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 trans-
fers to clock out the 12-bit conversion result). See Figure
20 for MAX146/MAX147 QSPI connections.
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 100kHz to 2MHz.
1) Set up the control byte for external clock mode and
call it TB1. TB1 should be of the format: 1XXXXX11
binary, where the Xs denote the particular channel
and conversion mode selected.
2) Use a general-purpose I/O line on the CPU to pull
CS
low.
3) Transmit TB1 and, simultaneously, receive a byte
and call it RB1. Ignore RB1.
4) Transmit a byte of all zeros ($00 hex) and, simulta-
neously, receive byte RB2.
5) Transmit a byte of all zeros ($00 hex) and, simulta-
neously, receive byte RB3.
6) Pull
CS
high.
Figure 6 shows the timing for this sequence. Bytes RB2
and RB3 contain the result of the conversion, padded
with one leading zero and three trailing zeros. The total
conversion time is a function of the serial-clock fre-
quency and the amount of idle time between 8-bit
transfers. To avoid excessive T/H droop, make sure the
total conversion time does not exceed 120μs.
Digital Output
In unipolar input mode, the output is straight binary
(Figure 17). For bipolar input mode, the output is two’s
complement (Figure 18). Data is clocked out at the
falling edge of SCLK in MSB-first format.
Cloc k Modes
The MAX146/MAX147 may use either an external
serial clock or the internal clock to perform the succes-
sive-approximation conversion. In both clock modes,
the external clock shifts data in and out of the
MAX146/MAX147. The T/H acquires the input signal as
the last three bits of the control byte are clocked into
DIN. Bits PD1 and PD0 of the control byte program the
clock mode. Figures 7–10 show the timing characteris-
tics common to both modes.
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MAX147ACAP+T 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 12-Bit 8Ch 133ksps 5.25V Precision ADC 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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MAX147ACPP 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 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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