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| 型号： | AD7741YR-REEL7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 7/12页 |
| 文件大小： | 0K |
| 描述： | IC CONVERTER V TO FREQ 8-SOIC |
| 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
TERMINOLOGY
INTEGRAL NONLINEARITY
For the VFC, Integral Nonlinearity (INL) is a measure of the
maximum deviation from a straight line passing through the
actual endpoints of the VFC transfer function. The error is
expressed in % of the frequency span:
Frequency Span = f OUT(max) – f OUT(min )
OFFSET ERROR
This is a measure of the offset error of the VFC. Ideally, the
minimum output frequency (corresponding to minimum input
voltage) is 5% of f CLKIN The deviation from this value is the
GENERAL DESCRIPTION
The AD7741/AD7742 are a new generation of CMOS synchro-
nous Voltage-to-Frequency Converters (VFCs) that use a
charge-balance conversion technique. The AD7741 is a single-
channel version and the AD7742 is a multichannel version. The
input voltage signal is applied to a proprietary programmable
gain front-end based around an analog modulator that converts
the input voltage into an output pulse train.
The parts also contain an on-chip +2.5 V bandgap reference
and operate from a single +5 V supply. A block diagram of the
AD7742 is shown in Figure 2.
offset error. It is expressed in terms of the error referred to the
input voltage. It is expressed in mV.
V IN 1
V IN 2
INPUT
SWITCHED
CAPS
INTEGRATOR
COMPARATOR
f OUT
GAIN ERROR
This is a measure of the span error of the VFC. The gain is the
V IN 3
V IN 4
MUX
SWITCHED
CAPS
scale factor that relates the input V IN to the output f OUT . The
gain error is the deviation in slope of the actual VFC transfer
characteristic from the ideal expressed as a percentage of the
full-scale span.
OFFSET ERROR DRIFT
This is a measure of the change in Offset Error with changes in
temperature. It is expressed in μ V/ ° C.
GAIN ERROR DRIFT
This is a measure of the change in Gain Error with changes in
temperature. It is expressed in (ppm of span)/ ° C.
POWER-SUPPLY REJECTION RATIO (PSRR)
This indicates how the output of the VFC is affected by changes
in the supply voltage. Again, this error is referred to the input
Figure 2. AD7742 Block Diagram
Input Amplifier Stage
The buffered input stage for the analog inputs presents a high
impedance, allowing significant external source impedances.
The four analog inputs (V IN 1 through V IN 4) each have a voltage
range from +0.5 V to V DD – 1.75 V. This is an absolute voltage
range and is relative to the GND pin.
In the case of the AD7742 multichannel part, a differential
multiplexer switches one of the differential input channels to the
VFC modulator. The multiplexer is controlled by two pins, A1
and A0. See Table I for channel configurations.
Table I. AD7742 Input Channel Selection
voltage. The input voltage is kept constant and the V DD supply
is varied ± 5%. The ratio of the apparent change in input voltage
to the change in V DD is measured in dBs.
CHANNEL-TO-CHANNEL ISOLATION
This is a ratio of the amplitude of the signal at the input of one
A1
0
0
1
1
A0
0
1
0
1
V IN (+)
V IN 1
V IN 2
V IN 3
V IN 1
V IN (–)
V IN 4
V IN 4
V IN 4
V IN 2
Type
Pseudo Differential
Pseudo Differential
Full Differential
Full Differential
channel to a sine wave on the input of another channel. It is
measured in dBs.
COMMON-MODE REJECTION
For the AD7742, the output frequency should remain un-
changed provided the differential input remains unchanged
although its common-mode level may change. The CMR is the
ratio of the apparent change in differential input voltage to the
actual change in common-mode voltage. It is expressed in dBs.
REV. 0
–7 –
Analog Input Ranges
The AD7741 has a unipolar single-ended input channel whereas
the AD7742 contains four input channels which may be con-
figured as two fully differential channels or as three pseudo-
differential channels. The AD7742 also has a X1/X2 gain
option on the front end. The channel and gain settings are
pin-programmable.
The AD7742 uses differential inputs to provide common-mode
noise rejection (i.e., the converted result will correspond to the
differential voltage between the two inputs). The absolute voltage
on both inputs must lie between +0.5 V and V DD –1.75 V.
相关PDF资料 |
PDF描述 |
|---|---|
| IDT7164S20YI8 | IC SRAM 64KBIT 20NS 28SOJ |
| AD7741BR-REEL7 | IC CONVERTER V TO FREQ 8-SOIC |
| IDT7164S20YI | IC SRAM 64KBIT 20NS 28SOJ |
| AD7741YR-REEL | IC CONVERTER V TO FREQ 8-SOIC |
| IDT7164S20Y8 | IC SRAM 64KBIT 20NS 28SOJ |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 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 |
| AD7742BN | 制造商:Analog Devices 功能描述:VFC Sync 2.75MHz 16-Pin PDIP 制造商:Rochester Electronics LLC 功能描述:SINGLE + MULTI-CHANNEL VFC I.C. - Bulk |
| AD7742BNZ | 制造商:Analog Devices 功能描述:VFC Sync 2.75MHz 16-Pin PDIP |
| AD7742BR | 制造商:AD 制造商全称:Analog Devices 功能描述:Single and Multichannel, Synchronous Voltage-to-Frequency Converters |
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