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參數資料
| 型號： | AD9954 |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | XO, clock |
| 英文描述： | 400 MSPS 14-Bit, 1.8 V CMOS Direct Digital Synthesizer |
| 中文描述： | 400 MSPS的14位，1.8伏的CMOS直接數字頻率合成 |
| 文件頁數： | 14/36頁 |
| 文件大小： | 1027K |
| 代理商： | AD9954 |
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AD9954
DAC Output
The AD9954 incorporates an integrated 14-bit current output
DAC.
Unlike most DACs, this output is referenced to AVDD,
not AGND.
Rev. 0 | Page 14 of 36
Two complementary outputs provide a combined full-scale
output current (I
OUT
). Differential outputs reduce the amount of
common-mode noise that might be present at the DAC output,
offering the advantage of an increased signal-to-noise ratio. The
full-scale current is controlled by means of an external resistor
(R
SET
) connected between the DAC_R
SET
pin and the DAC
ground (AGND_DAC). The full-scale current is proportional to
the resistor value as follows
OUT
SET
R
I
/
19
.
39
=
The maximum full-scale output current of the combined DAC
outputs is 15 mA, but limiting the output to 10 mA provides the
best spurious-free dynamic range (SFDR) performance. The DAC
output compliance range is AVDD + 0.5 V to AVDD – 0.5 V Volt-
ages developed beyond this range will cause excessive DAC distor-
tion and could potentially damage the DAC output circuitry.
Proper attention should be paid to the load termination to keep the
output voltage within this compliance range.
Comparator
Many applications require a square wave signal rather than a
sine wave. For example, in most clocking applications a high
slew rate helps to reduce phase noise and jitter. To support these
applications, the AD9954 includes an on-chip comparator. The
comparator has a bandwidth greater than 200 MHz and a
common-mode input range of 1.3 V to 1.8 V. By setting the
comparator power-down bit, CFR1<6>, the comparator can be
turned off to save on power consumption.
Linear Sweep Block
Linear sweep is a mode of operation whereby changes from a
start frequency (F0) to a terminal frequency (F1) are not instan-
taneous but instead are accomplished in a sweep or ramped
fashion. Frequency ramping, whether linear or nonlinear, neces-
sitates that many intermediate frequencies between F0 and F1
will be output in addition to the primary F0 and F1 frequencies.
The linear sweep block is comprised of the falling and rising
delta frequency tuning words, the falling and rising delta fre-
quency ramp rates, and the frequency accumulator. The linear
sweep enable bit CFR1 <21> enables the linear sweep block. In
addition, the linear sweep no dwell bit controls the linear sweep
block’s behavior upon reaching the terminal frequency in a
sweep. The actual method for programming a frequency sweep
is covered in the Modes of Operation section.
Serial IO Port
The AD9954 serial port is a flexible, synchronous serial communi-
cations port that allows easy interface to many industry-standard
microcontrollers and microprocessors. The serial I/O port is com-
patible with most synchronous transfer formats, including both the
Motorola 6905/11 SPI and Intel 8051 SSR protocols.
The interface allows read/write access to all registers that configure
the AD9954. MSB first or LSB first transfer formats are supported.
In addition, the AD9954’s serial interface port can be configured as
a single pin I/O (SDIO), which allows a 2-wire interface or two
unidirectional pins for in/out (SDIO/SDO), which enables a 3-wire
interface. Two optional pins, IOSYNC and CS, enable greater flexi-
bility for system design in the AD9954.
Register Maps and Descriptions
The register maps are listed in Table 7 and Table 8.
The appro-
priate register map depends on the state of the linear sweep
enable bit because certain registers are remapped depending
on which mode the part is operating in
. Specifically, Registers
0x07, 0x08, 0x09, and 0x0A act as the RAM segment control
words for each of the RAM profile slices when the linear sweep
enable bit is false. When the linear sweep enable bit is true, 0x07
becomes the negative linear sweep control word and 0x08
becomes the positive linear sweep control word. The 0x09 and
0x0A registers are not used in linear sweep mode. Because the
linear sweep operation takes precedence over RAM operations,
ADI recommends that the RAM enable bit CFR1<31> be set to
zero when the linear sweep enable bit CFR1<21> is true to
conserve power. The serial address numbers associated with
each of the registers are shown in hexadecimal format. Angle
brackets <> are used to reference specific bits or ranges of bits.
For example, <3> designates Bit 3, while <7:3> designates the
range of bits from 7 down to 3, inclusive.
Table 6. Register Mapping Based on Linear Sweep Enable Bit
Linear Sweep Enable Bit
Register Map
False (CFR1 <21> = 0)
RAM Segment Control Words Active
True (CFR1 <21> = 1)
Linear Sweep Control Words Active
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相關代理商/技術參數 |
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| AD9954/PCB | 制造商:Analog Devices 功能描述:AD9954 400 MSPS DDS W/ 14 BIT DAC EVALBD - Bulk 制造商:Analog Devices 功能描述:EVALUATION KIT ((NS)) |
| AD9954/PCBZ | 功能描述:BOARD EVAL FOR 9954 RoHS:是 類別:編程器，開發系統 >> 評估演示板和套件 系列:AgileRF™ 標準包裝:1 系列:PSoC® 主要目的:電源管理，熱管理 嵌入式:- 已用 IC / 零件:- 主要屬性:- 次要屬性:- 已供物品:板，CD，電源 |
| AD9954/PCBZ1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:400 MSPS, 14-Bit, 1.8 V CMOS, Direct Digital Synthesizer |
| AD9954_09 | 制造商:AD 制造商全稱:Analog Devices 功能描述:400 MSPS, 14-Bit, 1.8 V CMOS, Direct Digital Synthesizer |
| AD9954YSV | 制造商:Analog Devices 功能描述:Direct Digital Synthesizer 400MHz 1-DAC 14-Bit Serial 48-Pin TQFP EP 制造商:Rochester Electronics LLC 功能描述:400 MSPS DDS W/14 BIT DAC - Bulk 制造商:Analog Devices 功能描述:IC DDS 400MSPS SMD 9954 TQFP48 |
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