AD12401-XXXJWS データシートの表示（PDF） - Analog Devices

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AD12401-XXXJWS

12-Bit, 400 MSPS A/D Converter

Analog Devices 

AD12401

GAIN SELECT

The AD12401 is graded out for the gain mode and should be

ordered accordingly: the AD12401-xxxKWS is calibrated in the

low gain mode, and the AD12401-xxxJWS is calibrated in the

high gain mode. Performance is not guaranteed if either grade

is used in the wrong gain mode.

The high gain mode sets the analog input voltage to

approximately 1.6 V p-p. The low gain mode sets the analog

input voltage to approximately 3.2 V p-p. For high gain mode,

the user should pull Pin 103 (H/L_GAIN) up to 3.3 V using

a 4.02 kΩ resistor. For low gain mode, the user should ground

Pin 103.

THERMAL CONSIDERATIONS

The module is rated to operate over a case temperature of 0°C

to 60°C. To maintain the tight channel matching and reliability

of the AD12401, care must be taken to ensure that proper

thermal and mechanical considerations have been made and

addressed to ensure case temperature is kept within this range.

Each application requires evaluation of the thermal manage-

ment as applicable to the system design. This section provides

information that should be used in the evaluation of the

AD12401’s thermal management for each specific use.

In addition to the radiation of heat into its environment, the

AD12401 module enables the flow of heat through the

mounting studs and standoffs as they contact the motherboard.

As described in the Package Integrity/Mounting Guidelines

section, the module should be secured to the motherboard

using 2-56 nuts (washer use is optional). The torque on the nuts

should not exceed 32-inch ounces. Using a thermal grease at the

standoffs results in better thermal coupling between the board

and module. Depending on the ambient conditions, airflow can

be necessary to ensure the components in the module do not

exceed their maximum operating temperature. For reliability,

the most sensitive component has a maximum junction

temperature rating of 125°C.

Figure 22 and Figure 23 provide a basic guideline for two key

thermal management decisions: the use of thermal interface

material between the module bottom cover/mother board and

airflow. Figure 21 characterizes the typical thermal profile of an

AD12401 that is not using thermal interface material. Figure 22

provides the same information for a configuration that uses

gap-filling thermal interface material. In this case, Thermagon

T-flex 600 Series™, 0.040” thickness, was used. These profiles

show that the maximum die temperature is reduced by

approximately 2°C when thermal interface material is used.

Figure 22 and Figure 23 also provide a guideline for determining

the airflow requirements for given ambient conditions. For

example, a goal of 120°C die temperature in a 40°C ambient

environment without the use of thermal interface material

requires an airflow of 100 LFM.

From a channel-matching perspective, the most important

consideration is external thermal influences. It is possible for

thermal imbalances in the end application to adversely affect

the dynamic performance. Due to the temperature dependence

of the image spur, substantial deviation from the factory cali-

bration conditions can have a detrimental effect. Unbalanced

thermal influences can cause gradients across the module, and

performance degradation can result. Examples of unbalanced

thermal influences can include large heat dissipating elements

near one side of the AD12401, or obstructed airflow that does

not flow uniformly across the module. The thermal sensitivity

of the module can be affected by a change in thermal gradient

across the module of 2°C.

110

100

TYPICAL JUNCTION

90

80

70

60

CASE

50

40

AMBIENT

30

20

NO AIRFLOW

100 LFM

AIRFLOW CONDITION

300 LFM

Figure 22. Typical Temperature vs. Airflow with No Module/Board

Interface Material (Normalized to 60°C Module Case Temperature)

110

100

TYPICAL JUNCTION

90

80

70

60

CASE

50

40

AMBIENT

30

20

NO AIRFLOW

100 LFM

AIRFLOW CONDITION

300 LFM

Figure 23. Typical Temperature vs. Airflow with T-flex Module/Board

Interface Material (Normalized to 60°C Module Case Temperature Ambient)

PACKAGE INTEGRITY/MOUNTING GUIDELINES

The AD12401 is a printed circuit board (PCB)-based module

designed to provide mechanical stability and to support the

intricate channel-to-channel matching necessary to achieve high

dynamic range performance. The module should be secured to

the motherboard using 2-56 nuts (washer use is optional). The

torque on the nuts should not exceed 32-inch ounces.

Rev. A | Page 20 of 28

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