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| 型号： | AD9258BCPZ-125 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 22/44页 |
| 文件大小： | 0K |
| 描述： | IC ADC 14BIT 125MSPS DL 64LFCSP |
| 设计资源： | High Performance, Dual Channel IF Sampling Receiver (CN0140) |
| 标准包装： | 1 |
| 位数： | 14 |
| 采样率（每秒）： | 125M |
| 数据接口： | 串行 |
| 转换器数目： | 2 |
| 功率耗散（最大）： | 788mW |
| 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： | 64-VFQFN 裸露焊盘，CSP |
| 供应商设备封装： | 64-LFCSP-VQ（9x9） |
| 包装： | 托盘 |
| 输入数目和类型： | 2 个差分，单极 |
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AD9258
Rev. A | Page 29 of 44
VOLTAGE REFERENCE
A stable and accurate voltage reference is built into the AD9258.
The input range can be adjusted by varying the reference voltage
applied to the AD9258, using either the internal reference or an
externally applied reference voltage. The input span of the ADC
tracks reference voltage changes linearly. The various reference
modes are summarized in the sections that follow. The Reference
Decoupling section describes the best practices for PCB layout
of the reference.
Internal Reference Connection
A comparator within the AD9258 detects the potential at the
SENSE pin and configures the reference into four possible modes,
which are summarized in Table 11. If SENSE is grounded, the
reference amplifier switch is connected to the internal resistor
divider (see Figure 70), setting VREF to 1.0 V for a 2.0 V p-p full-
scale input. In this mode, with SENSE grounded, the full scale can
also be adjusted through the SPI port by adjusting Bit 6 and Bit 7
of Register 0x18. These bits can be used to change the full scale
to 1.25 V p-p, 1.5 V p-p, 1.75 V p-p, or to the default of 2.0 V p-p,
as shown in Table 17.
Connecting the SENSE pin to the VREF pin switches the reference
amplifier output to the SENSE pin, completing the loop and pro-
viding a 0.5 V reference output for a 1 V p-p full-scale input.
VREF
SENSE
0.5V
AD9258
SELECT
LOGIC
0.1F
1.0F
VIN–A/VIN–B
VIN+A/VIN+B
ADC
CORE
08
12
4-
0
40
Figure 70. Internal Reference Configuration
If a resistor divider is connected externally to the chip, as shown
in Figure 71, the switch again sets to the SENSE pin. This puts
the reference amplifier in a noninverting mode with the VREF
output, defined as follows:
+
×
=
R1
R2
VREF
1
5
.
0
The input range of the ADC always equals twice the voltage at
the reference (VREF) pin for either an internal or an external
reference.
0.5V
AD9258
SELECT
LOGIC
VIN–A/VIN–B
VIN+A/VIN+B
ADC
CORE
VREF
SENSE
0.1F
1.0F
R2
R1
08
12
4-
0
41
Figure 71. Programmable Reference Configuration
If the internal reference of the AD9258 is used to drive multiple
converters to improve gain matching, the loading of the reference
by the other converters must be considered. Figure 72 shows
how the internal reference voltage is affected by loading.
0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
LOAD CURRENT (mA)
RE
F
E
RE
NCE
V
O
L
T
A
G
E
RRO
R
(
%
)
08
12
4-
0
54
VREF = 1V
VREF = 0.5V
Figure 72. Reference Voltage Accuracy vs. Load Current
Table 11. Reference Configuration Summary
Selected Mode
SENSE Voltage
Resulting VREF (V)
Resulting Differential Span (V p-p)
External Reference
AVDD
N/A
2 × external reference
Internal Fixed Reference
VREF
0.5
1.0
Programmable Reference
0.2 V to VREF
+
×
R1
R2
1
0.5
(see Figure 71)
2 × VREF
Internal Fixed Reference
AGND to 0.2 V
1.0
2.0
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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD9258BCPZ-1251 | 制造商:AD 制造商全称:Analog Devices 功能描述:14-Bit, 80 MSPS/105 MSPS/125 MSPS, 1.8 V Dual Analog-to-Digital Converter (ADC) |
| AD9258BCPZ-80 | 功能描述:模数转换器 - ADC Dual 14 bit 80 high SNR ADC RoHS:否 制造商:Analog Devices 通道数量: 结构: 转换速率: 分辨率: 输入类型: 信噪比: 接口类型: 工作电源电压: 最大工作温度: 安装风格: 封装 / 箱体: |
| AD9258BCPZ-801 | 制造商:AD 制造商全称:Analog Devices 功能描述:14-Bit, 80 MSPS/105 MSPS/125 MSPS, 1.8 V Dual Analog-to-Digital Converter (ADC) |
| AD9258BCPZRL7-105 | 功能描述:模数转换器 - ADC Dual 14 bit 105 highSNR ADC RoHS:否 制造商:Analog Devices 通道数量: 结构: 转换速率: 分辨率: 输入类型: 信噪比: 接口类型: 工作电源电压: 最大工作温度: 安装风格: 封装 / 箱体: |
| AD9258BCPZRL7-1051 | 制造商:AD 制造商全称:Analog Devices 功能描述:14-Bit, 80 MSPS/105 MSPS/125 MSPS, 1.8 V Dual Analog-to-Digital Converter (ADC) |
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