- 您现在的位置：买卖IC网 > PDF目录22159 > AD7741BRZ-REEL7 (Analog Devices Inc)IC CONVERTER VOLT TO FREQ 8SOIC PDF资料下载
参数资料
| 型号： | AD7741BRZ-REEL7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 10/12页 |
| 文件大小： | 0K |
| 描述： | IC CONVERTER VOLT TO FREQ 8SOIC |
| 标准包装： | 1,000 |
| 类型： | 电压至频率 |
| 频率 - 最大： | 3.072MHz |
| 全量程： | ±50ppm/°C |
| 线性： | ±0.012% |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SO |
| 包装： | 带卷 (TR) |
| 配用： | EVAL-AD7741/42EBZ-ND - BOARD EVAL FOR AD7741/7742 |
AD7741/AD7742
APPLICATIONS
The basic connection diagram for the part is shown in Figure 9.
V IN
AD7741
f OUT
COUNTER
TO
P
In the connection diagram shown, the AD7742 analog inputs
are configured as fully differential, bipolar inputs with a gain of
1. A quartz crystal provides the master clock source for the part.
It may be necessary to connect capacitors (C1 and C2 in the
CLKIN
FREQUENCY
DIVIDER
GATE
SIGNAL
diagram) on the crystal to ensure that it does not oscillate at over-
tones of its fundamental operating frequency. The values of ca-
pacitors will vary depending on the manufacturer’s specifications.
CLOCK
GENERATOR
Figure 10. A/D Conversion Using the AD7741 VFC
+5V
4096x T CLOCK
f CLKIN
V IN 1
V DD
PD
DIFF
INPUT 1
V IN 2
REFOUT
REFIN
f OUT
T GATE
DIFF
INPUT 2
CHANNEL
SELECT
V IN 3
V IN 4
A0
A1
AD7742
f OUT
GND
UNI/ BIP
GAIN
GATE
Figure 11. Waveforms in an A/D Converter Using a VFC
The clock frequency and the gate time determine the resolution
CLKIN
C1
CLKOUT
C2
of such an ADC. If 12-bit resolution is required and f CLKIN is
5 MHz (therefore, f OUT max is 2.25 MHz), the minimum gate
time required is calculated as follows:
N counts at Full Scale (2.25 MHz) will take
Figure 9. Basic Connection Diagram
A/D Conversion Techniques Using the AD7741/AD7742
When used as an ADC, VFCs provide certain advantages in-
cluding accuracy, linearity and being inherently monotonic. The
AD7741/AD7742 has a true integrating input which smooths
out noise peaks.
The most popular method of using a VFC in an A/D system is
to count the output pulses of f OUT for a fixed gate interval (see
Figure 10). This fixed gate interval should be generated by
dividing down the clock input frequency. This ensures that any
errors due to clock jitter or clock frequency drift are eliminated.
The ratio of the f OUT to the clock frequency is what is important
here, not the absolute value of f OUT . The frequency division can
be done by a binary counter where f CLKIN is the CLK input.
Figure 11 shows the waveforms of f CLKIN , f OUT and the Gate
signal. A counter counts the rising edges of f OUT while the Gate
signal is high. Since the gate interval is not synchronized with
f OUT , there is a possibility of a counting inaccuracy. Depending
on f OUT, an error of one count may occur.
( N /2.25 × 10 6 ) seconds = minimum gate time.
N is the total number of codes for a given resolution; 4096 for
12 bits
minimum gate time = (4096/2.25 × 10 6 ) sec = 1.820 ms.
Since T GATE × f OUT max = number of counts at full scale, a
faster conversion with the same resolution can be performed
with a higher f OUT max. This high f OUT max (3 MHz) is a main
feature of the AD7741/AD7742.
If the output frequency is measured by counting pulses gated to
a signal which is derived from the clock, the clock stability is
unimportant and the device simply performs as a voltage-
controlled frequency divider, producing a high resolution ADC.
The inherent monotonicity of the transfer function and wide
range of input clock frequencies allows the conversion time and
resolution to be optimized for specific applications.
There is another parameter is taken into account when choosing
the length of the gate interval. Because the integration period of
the system is equal to the gate interval, any interfering signal can
be rejected by counting for an integer number of periods of the
interfering signal. For example, a gate interval of 100 ms will
give normal-mode rejection of 50 Hz and 60 Hz signals.
–10 –
REV. 0
相关PDF资料 |
PDF描述 |
|---|---|
| R0.25D12-1209/P | CONV DC/DC 0.25W 12VIN +/-9V OUT |
| AD7741BRZ-REEL | IC CONVERTER VOLT TO FREQ 8SOIC |
| R0.25D12-1209/H | CONV DC/DC 0.25W 12VIN +/-9V OUT |
| R0.25D12-1205/P | CONV DC/DC 0.25W 12VIN +/-5V OUT |
| EN93L3X2 | BATTERY PK 9.0V C SIZE ALKALINE |
相关代理商/技术参数 |
参数描述 |
|---|---|
| AD7741YR | 制造商:Analog Devices 功能描述:VFC Sync 1.35MHz 8-Pin SOIC N |
| AD7741YR-REEL | 功能描述:IC CONVERTER V TO FREQ 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - V/F 和 F/V 转换器 系列:- 标准包装:1 系列:- 类型:频率至电压 频率 - 最大:10kHz 全量程:- 线性:±0.3% 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SOIC 包装:Digi-Reel® 其它名称:LM2917MX-8/NOPBDKR |
| AD7741YR-REEL7 | 功能描述:IC CONVERTER V TO FREQ 8-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - V/F 和 F/V 转换器 系列:- 标准包装:1 系列:- 类型:频率至电压 频率 - 最大:10kHz 全量程:- 线性:±0.3% 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SOIC 包装:Digi-Reel® 其它名称:LM2917MX-8/NOPBDKR |
| AD7741YRZ | 功能描述:IC CONVERTER VOLT TO FREQ 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - V/F 和 F/V 转换器 系列:- 标准包装:1 系列:- 类型:频率至电压 频率 - 最大:10kHz 全量程:- 线性:±0.3% 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 供应商设备封装:8-SOIC 包装:Digi-Reel® 其它名称:LM2917MX-8/NOPBDKR |
| AD7742 | 制造商:AD 制造商全称:Analog Devices 功能描述:Single and Multichannel, Synchronous Voltage-to-Frequency Converters |
发布紧急采购，3分钟左右您将得到回复。