参数资料
| 型号： | AD768AR |
| 厂商： | Analog Devices Inc |
| 文件页数： | 18/20页 |
| 文件大小： | 0K |
| 描述： | IC DAC 16BIT 30MSPS 28-SOIC |
| 产品培训模块： | Data Converter Fundamentals DAC Architectures |
| 标准包装： | 1 |
| 设置时间： | 25ns |
| 位数： | 16 |
| 数据接口： | 并联 |
| 转换器数目： | 1 |
| 电压电源： | 双 ± |
| 功率耗散（最大）： | 600mW |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SOIC（0.295"，7.50mm 宽） |
| 供应商设备封装： | 28-SOIC W |
| 包装： | 管件 |
| 输出数目和类型： | 2 电流，单极；2 电流，双极 |
| 采样率（每秒）： | 40M |
AD768
REV. B
–7–
REFERENCE OUTPUT
The internal 2.5 V bandgap reference is provided for generation
of the IREFIN current, and must be compensated externally with
a capacitor of 0.1
F or greater from REFOUT to REFCOM. If
an external reference is used, REFOUT should be tied directly
to the positive supply voltage, VDD. This effectively turns off the
internal reference, eliminating the need for the external capaci-
tor at REFOUT. The reference is specified to drive a nominal
load of 5 mA with a maximum of 15 mA. Operation with a
heavier load will result in degradation of supply rejection and
reference voltage accuracy. Therefore, the reference output
should be buffered with an amplifier when additional load cur-
rent is required. A properly sized pull-up resistor can also be
used to source additional current to the load. The resistors value
should be selected such that REFOUT will always source a
minimum of 5 mA to IREFIN and the additional load.
AD768
IREFIN
REFOUT
REFCOM
CREFCOMP
1F
500
5
3
6
Figure 6. Typical Reference Hookup
TEMPERATURE CONSIDERATIONS
Note that the reference plays a key role in the overall tempera-
ture performance of the AD768. Any drift of IREFIN shows up
directly in IOUT. When the output is taken as a current, the drift
of IREFIN (which depends on both VREF and RREF) must be mini-
mized. This can be done by using the internal temperature com-
pensated reference for VREF and a low temperature coefficient
resistor for RREF. If the output is taken as a voltage, it is a func-
tion of a resistor ratio, not an absolute resistor value. By select-
ing resistors with matched temperature coefficients for RREF
and RLOAD, the drift in the resistor values will cancel, providing
optimal drift performance.
REFERENCE NOISE REDUCTION AND MULTIPLYING
BANDWIDTH
For application flexibility and multiplying capabilities, the refer-
ence amplifier is designed to offer adjustable bandwidth that can
be reduced by connecting an external capacitor from the NR
node to the negative supply pin, VEE. This capacitor limits the
bandwidth and acts as a filter to reduce the noise contribution
from the reference amplifier.
The noise reduction capacitor, CNR, is not required for stability
and does not affect the settling time of the DAC output. With-
out this capacitor, the IREFIN bandwidth is 15 MHz allowing
high frequency modulation of the DAC full-scale range through
the reference input node. Figure 7 shows the relationship be-
tween the external noise reduction capacitor and the –3 dB
bandwidth of the reference amplifier.
NOISE REDUCTION CAPACITOR – F
BANDWIDTH
–
Hz
100M
1k
10p
1
100p
1n
10n
100n
10M
1M
100k
10k
Figure 7. External Noise Reduction Capacitor vs. –3 dB
Bandwidth
The sensitivity of the NR node requires that care be taken in
capacitor placement. The capacitor should be located as physi-
cally close to the package pins as possible and lead lengths
should be minimized. For this purpose, the use of a chip
capacitor is recommended. For applications that do not require
high frequency modulation at IREFIN, it is recommended that
a capacitor on the order of 1
F be connected from NR to V
EE.
If the reference input is purely dc, noise may be minimized with
multiple capacitors, such as 1
F and 0.1 F, to more effectively
filter both high and low frequency disturbances.
ANALOG OUTPUTS
The AD768 offers two analog outputs; IOUTA is trimmed for
optimal INL and DNL performance and has a full-scale output
when all bits are high. For applications that require the specified
dc accuracy, IOUTA should be used. IOUTB is the comple-
mentary output with full-scale output when all bits are low.
Both IOUTA and IOUTB provide similar dynamic perfor-
mance. Refer to Figures 8 and 9 for typical INL and DNL per-
formance curves. The outputs can also be used differentially.
Refer to the section “Applying the AD768” for examples of vari-
ous output configurations.
DIGITAL INPUT CODE – k
8
–8
065
10
20
30
40
4
–2
–4
–6
6
0
2
INL
ERROR
–
LSB
50
60
5
152535
4555
Figure 8. Typical INL Performance
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| AD768AR-REEL | 制造商:Analog Devices 功能描述:DAC 1-CH R-2R/Current Steering 16-bit 28-Pin SOIC W T/R |
| AD768ARZ | 功能描述:IC DAC 16BIT 30MSPS 28-SOIC RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:- 标准包装:1 系列:- 设置时间:4.5µs 位数:12 数据接口:串行，SPI? 转换器数目:1 电压电源:单电源 功率耗散（最大）:- 工作温度:-40°C ~ 125°C 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-SOICN 包装:剪切带 (CT) 输出数目和类型:1 电压，单极；1 电压，双极 采样率（每秒）:* 其它名称:MCP4921T-E/SNCTMCP4921T-E/SNRCTMCP4921T-E/SNRCT-ND |
| AD768ARZ-REEL | 功能描述:IC DAC 16BIT 30MSPS 28-SOIC RoHS:是 类别:集成电路 (IC) >> 数据采集 - 数模转换器 系列:- 产品培训模块:Data Converter Fundamentals DAC Architectures 标准包装:750 系列:- 设置时间:7µs 位数:16 数据接口:并联 转换器数目:1 电压电源:双 ± 功率耗散（最大）:100mW 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:28-LCC（J 形引线） 供应商设备封装:28-PLCC（11.51x11.51） 包装:带卷 (TR) 输出数目和类型:1 电压，单极；1 电压，双极 采样率（每秒）:143k |
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| AD768-EBZ | 制造商:Analog Devices 功能描述:EVAL BOARD - Boxed Product (Development Kits) |
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