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| 型号： | AD7472ARZ |
| 厂商： | Analog Devices Inc |
| 文件页数： | 4/21页 |
| 文件大小： | 0K |
| 描述： | IC ADC 12BIT PARALLEL 24SOIC |
| 标准包装： | 31 |
| 位数： | 12 |
| 采样率（每秒）： | 1.5M |
| 数据接口： | 并联 |
| 转换器数目： | 1 |
| 功率耗散（最大）： | 12mW |
| 电压电源： | 模拟和数字 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 24-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 24-SOIC W |
| 包装： | 管件 |
| 输入数目和类型： | 1 个单端，单极 |
REV. B
AD7470/AD7472
–11–
ADC TRANSFER FUNCTION
The output coding of the AD7470/AD7472 is straight binary.
The designed code transitions occur midway between succes-
sive integer LSB values (0.5 LSB, 1.5 LSB, etc). The LSB
size is equal to (REF IN)/4096 for the AD7472 and to (REF
IN)/1024 for the AD7470. The ideal transfer characteristic for
the AD7472 is shown in Figure 6.
111...111
111...110
111...000
011...111
000...010
000...001
000...000
ADC
CODE
0V 0.5LSB
VREF –1.5LSB
ANALOG INPUT
1LSB = VREF/4096
Figure 6. Transfer Characteristic for 12 Bits
AC ACQUISITION TIME
In ac applications it is recommended to always buffer analog
input signals. The source impedance of the drive circuitry must
be kept as low as possible to minimize the acquisition time of
the ADC. Large values of impedance at the VIN pin of the ADC
will cause the THD to degrade at high input frequencies.
The AD8021, AD8047, AD8051, AD9631, and AD797 are
some of the op amps that could be used to buffer the analog
input. Figure 7 shows the AD7470/AD7472 performance for
some of those recommended input buffers.
TYPICAL AMPLIFIER
INPUT
SNR
THD
CURRENT
BUFFERS
500kHz
CONSUMPTION
AD8047
70
78
5.8mA
AD9631
69.5
80
17mA
AD8051
68.6
78
4.4mA
AD797
70
84
8.2mA
AD7470/AD7472
DYNAMIC
PERFORMANCE
SPECIFICATIONS
Figure 7. Recommended Input Buffers
Reference Input
The following references are best suited for use with the
AD7470/AD7472.
ADR291
AD780
REF192
ADR421
For optimum performance, a 2.5 V reference is recommended.
The parts can function with a reference up to 3 V and down to
2 V, but the performance deteriorates.
DC ACQUISITION TIME
The ADC starts a new acquisition phase at the end of a conver-
sion and ends it on the falling edge of the
CONVST signal. At
the end of conversion there is a settling time associated with the
sampling circuit. This settling time lasts approximately 135 ns.
The analog signal on VIN is also being acquired during this
settling time; therefore, the minimum acquisition time needed is
approximately 135 ns.
Figure 8 shows the equivalent charging circuit for the sampling
capacitor when the ADC is in its acquisition phase. R3 repre-
sents the source impedance of a buffer amplifier or resistive
network, R1 is an internal switch resistance, R2 is for bandwidth
control, and C1 is the sampling capacitor. C2 is back-plate
capacitance and switch parasitic capacitance.
During the acquisition phase the sampling capacitor must be
charged to within
±1 LSB of its final value.
R3
R1
125
VIN
C1
22pF
C2
8pF
R2
636
Figure 8. Equivalent Sampling Circuit
ANALOG INPUT
Figure 9 shows the equivalent circuit of the analog input struc-
ture of the AD7470/AD7472. The two diodes, D1 and D2,
provide ESD protection for the analog inputs. The capacitor C3
is typically about 4 pF and can be primarily attributed to pin
capacitance. The resistor R1 is an internal switch resistance.
This resistor is typically about 125
. The capacitor C1 is the
sampling capacitor, while R2 is used for bandwidth control.
R1
125
VIN
C1
22pF
C2
8pF
R2
636
D1
D2
C3
4pF
VDD
Figure 9. Equivalent Analog Input Circuit
CLOCK SOURCES
The max CLK specification for the AD7470 is 30 MHz, and for
the AD7472, it is 26 MHz. These frequencies are not standard
off-the-shelf oscillator frequencies. Many manufacturers pro-
duce oscillator modules close to these frequencies; a typical one
being 25.175 MHz from IQD Limited. AEL Crystals Limited
produces a 25 MHz oscillator module in various packages. Crys-
tal oscillator manufacturers will produce 26 MHz and 30 MHz
oscillators to order. Of course any clock source can be used, not
just crystal oscillators.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD7472BR | 制造商:Analog Devices 功能描述:ADC Single SAR 1.5Msps 12-bit Parallel 24-Pin SOIC W 制造商:Rochester Electronics LLC 功能描述:12 BIT 1.5MSPS PARALLEL ADC I.C. - Bulk 制造商:Analog Devices 功能描述:SEMICONDUCTORS ((NW)) |
| AD7472BR-REEL | 制造商:AD 制造商全称:Analog Devices 功能描述:1.75 MSPS, 4 mW 10-Bit/12-Bit Parallel ADCs |
| AD7472BR-REEL7 | 功能描述:IC ADC 12BIT PARALLEL 24-SOIC RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 系列:- 位数:12 采样率（每秒）:300k 数据接口:并联 转换器数目:1 功率耗散（最大）:75mW 电压电源:单电源 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-SOIC（0.295"，7.50mm 宽） 供应商设备封装:24-SOIC 包装:带卷 (TR) 输入数目和类型:1 个单端，单极；1 个单端，双极 |
| AD7472BRU | 功能描述:IC ADC 12BIT PARALLEL 24-TSSOP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 系列:- 位数:12 采样率（每秒）:300k 数据接口:并联 转换器数目:1 功率耗散（最大）:75mW 电压电源:单电源 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-SOIC（0.295"，7.50mm 宽） 供应商设备封装:24-SOIC 包装:带卷 (TR) 输入数目和类型:1 个单端，单极；1 个单端，双极 |
| AD7472BRU-REEL | 功能描述:IC ADC 12BIT PARALLEL 24-TSSOP RoHS:否 类别:集成电路 (IC) >> 数据采集 - 模数转换器 系列:- 标准包装:1,000 系列:- 位数:12 采样率（每秒）:300k 数据接口:并联 转换器数目:1 功率耗散（最大）:75mW 电压电源:单电源 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:24-SOIC（0.295"，7.50mm 宽） 供应商设备封装:24-SOIC 包装:带卷 (TR) 输入数目和类型:1 个单端，单极；1 个单端，双极 |
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