參數(shù)資料
型號(hào)： AD9852AST
廠商： ANALOG DEVICES INC
元件分類： XO, clock
英文描述： CMOS 300 MHz Complete-DDS
中文描述： PLL FREQUENCY SYNTHESIZER, 20 MHz, PQFP80
封裝： MS-026BEC, LQFP-80
文件頁(yè)數(shù)： 31/42頁(yè)
文件大小： 424K
代理商： AD9852AST
AD9852
–31–
REV. 0
POWER DISSIPATION AND THERMAL
CONSIDERATIONS
The AD9852 is a multifunctional, very high-speed device that
targets a wide variety of synthesizer and agile clock applications.
The set of numerous innovative features contained in the device
each consume incremental power, the sum of which, if enabled
in combination, may exceed the safe thermal operating condi-
tions of the device. Careful analysis and consideration of power
dissipation and thermal management is a critical element in the
successful application of the AD9852 device.
The AD9852 device is specified to operate within the industrial
temperature range of –40
°
C to +85
°
C. This specification is
conditional, however, such that the absolute maximum junction
temperature of 150
°
C is not exceeded. At high operating tempera-
tures, extreme care must be taken in the operation of the device
to avoid exceeding the junction temperature which results in a
potentially damaging thermal condition.
Many variables contribute to the operating junction temperature
within the device, including:
1.
Package Style
2.
Selected Mode of Operation
3.
Internal System Clock Speed
4.
Supply Voltage
5.
Ambient Temperature.
The combination of these variables determines the junction
temperature within the AD9852 device for a given set of operating
conditions.
The AD9852 device is available in two package styles: a thermally-
enhanced surface-mount package with an exposed heat sink,
and a nonthermally-enhanced surface-mount package. The
thermal impedance of these packages are 16
°
C/W and 38
°
C/W
respectively, measured under still air conditions.
THERMAL IMPEDANCE
The thermal impedance of a package can be thought of as a
thermal resistor that exists between the semiconductor surface
and the ambient air. The thermal impedance of a package is
determined by package material and its physical dimensions. The
dissipation of the heat from the package is directly dependent upon
the ambient air conditions and the physical connection made
between the IC package and the PCB. Adequate dissipation of
power from the AD9852 relies upon all power and ground pins
of the device being soldered directly to a copper plane on a PCB.
In addition, the thermally-enhanced package of the AD9852ASQ
contains a heat sink on the bottom of the package that must be
soldered to a ground pad on the PCB surface. This pad must be
connected to a large copper plane which, for convenience, may be
ground plane. Sockets for either package style of the AD9852
device are not recommended.
JUNCTION TEMPERATURE CONSIDERATIONS
The power dissipation (P
DISS
) of the AD9852 device in a given
application is determined by many operating conditions. Some
of the conditions have a direct relationship with P
DISS
, such as
supply voltage and clock speed, but others are less deterministic.
The total power dissipation within the device, and its effect
on the junction temperature, must be considered when using the
device. The junction temperature of the device is given by:
J
unction Temperature = (Thermal Impedance
×
Power Consumption) + Ambient Temperature
Given that the junction temperature should never exceed 150
°
C
for the AD9852, and that the ambient temperature can be 85
°
C,
the maximum power consumption for the AD9852AST is 1.7 W
and the AD9852ASQ (thermally-enhanced package) is 4.1 W.
Factors affecting the power dissipation are:
Supply Voltage
—this obviously affects power dissipation and
junction temperature since P
DISS
equals V
×
I. Users should
design for 3.3 V nominal, however the device is guaranteed to
meet specifications over the full temperature range and over
the supply voltage range of 3.135 V to 3.465 V.
Clock Speed
—this directly and linearly influences the total power
dissipation of the device and, therefore, junction temperature.
As a rule, to minimize power dissipation, the user should always
select the lowest internal clock speed possible to support a given
application. Normally the usable frequency output bandwidth
from a DDS is limited to 40% of the clock rate to keep reasonable
requirements on the output low-pass filter. For the typical DDS
application, the system clock frequency should be 2.5 times
the highest desired output frequency.
Mode of Operation
—the selected mode of operation for the
AD9852 has a great influence on total power consumption. The
AD9852 offers many features and modes, each of which imposes
an additional power requirement. The collection of features
contained in the AD9852 target a wide variety of applications
and the device was designed under the assumption that only a
few would be enabled for any given application. In fact, the user
must understand that enabling multiple features at higher clock
speeds may cause the junction temperature of the die to be
exceeded. This can severely limit the long-term reliability of the
device. Figure 57 provides a summary of the power require-
ments associated with the individual features of the AD9852.
This table should be used as a guide in determining the optimum
application of the AD9852 for reliable operation.
As can be seen in the Figure 57, the Inverse Sinc filter function
requires a significant amount of power, and much forethought
and scrutiny should be given to its use. As an alternate approach
to maintaining flatness across the output bandwidth, the Digital
Multiplier function may be used to adjust the output signal
level, at a dramatic savings in power consumption. Careful plan-
ning and management in the use of the feature set will minimize
power dissipation and avoid exceeding junction temperature
requirements within the IC.
相關(guān)PDF資料
PDF描述
AD9853-45PCB Programmable Digital OPSK/16-QAM Modulator
AD9853-65PCB Programmable Digital OPSK/16-QAM Modulator
AD9853AS Programmable Digital OPSK/16-QAM Modulator
AD9854ASQ CMOS 300 MHz Quadrature Complete-DDS
AD9854AST CMOS 300 MHz Quadrature Complete-DDS
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
AD9852ASTZ 功能描述:IC DDS SYNTHESIZER CMOS 80-LQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 直接數(shù)字合成 (DDS) 系列:- 產(chǎn)品變化通告:Product Discontinuance 27/Oct/2011 標(biāo)準(zhǔn)包裝:2,500 系列:- 分辨率（位）:10 b 主 fclk:25MHz 調(diào)節(jié)字寬（位）:32 b 電源電壓:2.97 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:帶卷 (TR)
AD9852ASTZ 制造商:Analog Devices 功能描述:IC DDS 100MHZ LQFP-80
AD9852ASTZ1 制造商:AD 制造商全稱:Analog Devices 功能描述:CMOS 300 MSPS Complete DDS
AD9852ASVZ 功能描述:IC DDS SYNTHESIZER CMOS 80-TQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 直接數(shù)字合成 (DDS) 系列:- 產(chǎn)品變化通告:Product Discontinuance 27/Oct/2011 標(biāo)準(zhǔn)包裝:2,500 系列:- 分辨率（位）:10 b 主 fclk:25MHz 調(diào)節(jié)字寬（位）:32 b 電源電壓:2.97 V ~ 5.5 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:帶卷 (TR)
AD9852ASVZ 制造商:Analog Devices 功能描述:IC DDS 300MHz TQFP-80 制造商:Analog Devices 功能描述:IC, DDS, 300MHz, TQFP-80
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*