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THS6012 500 mA Dual Differential Drivers Evaluation Module
User's Guide
November 1998
Mixed-Signal Products
SLOU034
IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI's standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE ("CRITICAL APPLICATIONS"). TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED, AUTHORIZED, OR WARRANTED TO BE SUITABLE FOR USE IN LIFE-SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER'S RISK. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI's publication of information regarding any third party's products or services does not constitute TI's approval, warranty or endorsement thereof.
Copyright (c) 1998, Texas Instruments Incorporated
Preface
Related Documentation From Texas Instruments
J J J
THS6012 500-mA DUAL DIFFERENTIAL DRIVERS (literature number SLOS226). This is the data sheet for the THS6012 amplifier integrated circuit used on the EVM THS4001 HIGH-SPEED LOW-POWER OPERATIONAL AMPLIFIER (literature number SLOS206) This is the data sheet for the THS4001 amplifier integrated circuit used on the EVM. PowerPADTM Thermally Enhanced Package (literature number SLMA002) This is the technical brief for the special PowerPAD package in which the THS6012 amplifier IC is supplied.
FCC Warning
This equipment is intended for use in a laboratory test environment only. It generates, uses, and can radiate radio frequency energy and has not been tested for compliance with the limits of computing devices pursuant to subpart J of part 15 of FCC rules, which are designed to provide reasonable protection against radio frequency interference. Operation of this equipment in other environments may cause interference with radio communications, in which case the user at his own expense will be required to take whatever measures may be required to correct this interference.
Trademarks
TI is a trademark of Texas Instruments Incorporated.
Chapter Title--Attribute Reference
iii
iv
Running Title--Attribute Reference
Contents
1 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Input Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 THS6012 EVM Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Using The THS6012 EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 THS6012 EVM Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 General High-Speed Amplifier Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 General PowerPAD Design Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1-2 1-2 1-5 1-5 1-6 1-7 1-8 1-9
2
Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.1 THS6012 Dual Differential Line Drivers EVM Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.2 THS6012 EVM Board Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Chapter Title--Attribute Reference
v
Running Title--Attribute Reference
Figures
1-1 1-2 1-3 1-4 1-5 1-6 1-7 2-1 2-2 2-3 2-4 THS6012 Evaluation Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 THS6012 Evaluation Module Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 THS6012 Evaluation Module Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 THS6012 EVM Driver Frequency Response With a 50-W Load . . . . . . . . . . . . . . . . . . . . . 1-7 THS6012 EVM Driver Frequency Response Test Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7 PowerPAD PCB Etch and Via Pattern - Minimum Requirements . . . . . . . . . . . . . . . . . . . . 1-9 Maximum Power Dissipation vs. Free-Air Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 THS6012 EVM Component Placement Silkscreen and Layout . . . . . . . . . . . . . . . . . . . . . . THS6012 EVM PC Board: Layer 1 -- Top Side Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . THS6012 EVM PC Board: Layer 2 -- Back Side Ground Plane Layer . . . . . . . . . . . . . . . . THS6012 EVM PC Board: Solder Mask -- Back Side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 2-3 2-4 2-4
vi
Chapter 1
General Information
This chapter details the Texas Instruments (TITM) THS6012 500-mA Dual Differential Line Driver Evaluation Module (EVM), SLOP132. It includes a list of EVM features, a brief description of the module illustrated with a pictorial and schematic diagrams, EVM specifications, details on configuring, connecting, and using the EVM, and a discussion on high-speed amplifier and PowerPAD package design considerations.
Topic
1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9
Page
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 Receiver Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6 Input Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8 THS6012 EVM Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9 Using The THS6012 EVM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 THS6012 EVM Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-11 General High-Speed Amplifier Design Considerations . . . . . . . . . 1-14 General PowerPADTM Design Considerations . . . . . . . . . . . . . . . . . . 1-15
General Information
1-1
Features
1.1 Features
THS6012 500-mA Dual Differential Driver EVM features include:
J J J J J J J J
A Complete Central Office Side ADSL Differential Line Driver Multiple Input Configurations Set Via On-Board Jumpers A THS4001 High-Speed Amplifier as an Inverter Standard BNC Connectors Inputs and Outputs 5-V to 15-V Operation Nominal 50- Impedance Inputs Pad Area On Board For User Component Placement and Testing Good Example of PowerPAD Package and High-Speed Amplifier Design and Layout
1.2 Description
The TI THS6012 500-mA Dual Differential Line Driver Evaluation Module (EVM) is a complete central office side ADSL high-speed driver circuit. It consists of the TI THS6012 Dual Differential Line Driver IC, a TI THS4001 High-Speed, Low-Power Operational Amplifier IC, and a number of passive parts, all mounted on a multilayer circuit board (Figure 1-1). The EVM uses standard BNC connectors for inputs and outputs and also includes a pad area for user component connection and testing. It is completely assembled, fully tested, and ready to use -- just connect it to power, a signal source, and a load (if desired).
Figure 1-1. THS6012 Evaluation Module
+VCC J1 J2 GND J3 -VCC
L1 +
C1
C8
L2
R8 C2 C13
C14 C9
Driver 1 Input
+
J4 R1 R2 C3
J5
Driver 1 Output
Texas Instruments THS6012 EVM SLOP132 Rev. B
U2 C10 R3 R12 Pad1 GND Pad2
R5 R6 U1
R4 C5 R13 JP2 R10 J6 J7 R15 R9 JP1 C7
Driver 2 Input
Driver 2 Output
1-2
General Information
Description
Input power is applied to the EVM through banana jacks J1, J2, and J3. An LC filter on each power bus isolates the EVM circuits from the external supply. The schematic for the EVM appears in Figure 1-2.
Figure 1-2. THS6012 Evaluation Module Schematic
J1 J2 J3 L2 0.22 H R4 1 k 15 V R3 1 k R7 TBD Driver 1 Input 5 R2 49.9 4 J4 C4 R1 49.9 TBD - 3 U2:A THS6012 2 + 1 C3 0.1 F C13 0.1 F R8 12.4 J5 -15 V C2 0.1 F Pad1 Pad2 1 OUT GND C6 TBD R13 1 k 15 V R12 1 k C10 0.1 F 2 OUT Driver 1 Output
L1 0.22 H
C1 6.8 F 15 V
C8 6.8 F
-15 V
R5 1 k
R6 1 k 15 V C5 0.1 F U1 THS4001 6 + 3 Driver 2 Input J6 4 -15 V C7 0.1 F
R14 TBD Driver 2 Output
2
-
7
16 JP1 1 R9 49.9 R11 TBD 1 C12 TBD C11 TBD
18 -
U2:B THS6012 19 C14 0.1 F R15 12.4
17
+ 20
J7 C9 0.1 F
-15 V
R10 49.9
JP2
General Information
1-3
Description
The THS6012 EVM is equipped with a separate BNC connector for the Driver 1 input and the Driver 2 input. Each input is terminated with a 50- resistor to provide correct line impedance matching (Figure 1-2). Using a source with a 50- output impedance will create a voltage divider at the EVM inputs. Thus, accurate knowledge of the source output characteristics is required to determine proper input signal amplitudes. Driver outputs are routed through central office side ADSL-standard 12.4- resistors to provide correct transmission line impedance matching when run through a 1:2 transformer with a 100- termination. These resistors also allow separate receivers to view a differential input signal from the transmission line. All of the amplifiers on the EVM (THS6012 and THS4001) follow the classic operational amplifier gain equations: Inverting Gain
+ -RRF
G R + 1 ) RF G
(1)
Noninverting Gain
(2)
The gain of the amplifiers can be easily changed to support different applications by changing resistor ratios. Any of the components on the EVM board can be replaced with different values. Also, component pads have been placed in convenient locations on the PCB (shown as components with the value X in the schematic) to allow numerous modifications to the basic EVM configuration. However, care must be taken, because the surface mount solder pads on the board are somewhat fragile and will not survive a large number of soldering/desoldering operations. The THS6012 IC is a current-feedback amplifier (CFB), and, because of this, extra care must be taken to ensure that a feedback resistor is always included in the design. In addition, there must never be a capacitor directly in the feedback path between the noninverting input and the amplifier output. Disregarding this guideline will likely result in a part that oscillates. The THS4001 IC amplifier used on the EVM, however, is a classic voltage-feedback amplifier (VFB) and has no restrictions on resistors or capacitors in the feedback path. But, to maximize bandwidth, high value resistors and capacitors should be used with discretion. Finally, the EVM circuit board is a good example of proper board layout for high-speed amplifier and PowerPAD designs. It can be used as a guide for user application layouts.
1-4
General Information
Input Configuration
1.3 Input Configuration
The THS6012 EVM inputs can be configured in several different ways to provide a wide variety of circuits to support different applications (Figure 1-3). Each of the two jumpers on the EVM is a three-pin header that is used as a SPDT switch by placing a shunt across two pins to select either of two possible signal routes.
Figure 1-3. THS6012 Evaluation Module Block Diagram
Driver 1 Input J4 U1
THS4001
U2: A
THS6012
Driver 1 Output J5
JP1 1 JP2 1 2 3 2 3 + -
Positive Driver U2: B J7 Driver 2 Output Negative Driver
Driver 2 Input J6
Inverter
THS6012
-
Jumper JP1:
J J J J
-
1-2 -- connects the noninverting input of driver 2 (U2: B) to the THS4001 inverting amplifier (U1) output 2-3 -- connects the noninverting input of driver 2 (U2: B) to the input connector (J6) when jumper JP2 is set appropriately
Jumper JP2: 1-2 -- connects the driver 2 input connector (J6) to the noninverting input of driver 2 (U2:B) when jumper JP1 is set appropriately 2-3 -- connects the driver 2 input connector (J6) to the inverting input of driver 2 (U2:B) when jumper JP1 is set appropriately
For example, to use a single-ended input, jumper JP1 should be set to 1-2 and the input signal applied to input connector J4. The output of the THS6012 drivers is a differential signal due to the inverter (U1) and JP1 being set to 1-2. For a differential source, JP1 should be set to 2-3, JP2 should be set to 1-2 and the differential input signal applied between input connectors J4 and J6. If JP2 is in the 2-3 position, components C12 and R11 must be installed, R9 must be removed, and a 0- resistor must be installed in the C11 position for proper operation.
1.4 THS6012 EVM Specifications
Supply voltage range, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 V to 15 V Supply current, ICC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 mA Input voltage, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VCC, max Output drive, THS6012 Drivers, IO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 500 mA, typ each Continuous total power dissipation at TA = 25C (THS6012), . . . . . . . . . . . . . . . . . . . 5.8 W, max For complete THS6012 amplifier IC specifications, parameter measurement information, and additional application information, see the THS6012 data sheet, TI Literature Number SLOS226.
General Information
1-5
Using The THS6012 EVM
1.5 Using The THS6012 EVM
The THS6012 EVM operates from a split power supply with voltages ranging from 5 V to 15 V. The use of a single supply for this EVM is not recommended. As shipped, the output of driver 1 is equal to a noninverting gain of 2 when using the single-ended input mode. The output of driver 2 is equal to an inverting gain of 2 under the same conditions. An oscilloscope is typically used to view and analyze the EVM output signals. 1) Ensure that all power supplies are set to OFF before making power supply connections to the THS6012 EVM. 2) Select the operating voltage for the EVM and connect appropriate split power supplies to the banana jacks on the module marked +VCC (J1) and -VCC (J3). 3) Connect the power supply ground to the module banana jack marked GND (J2). 4) Connect an oscilloscope probe to U2, pin2. This is the driver 1 amplifier output. Connecting directly to the DRIVER 1 OUTPUT BNC connector (J5) with a 50- nominal impedance cable and probe is not recommended. The source impedance of driver 1 is only 12.4 ; such a connection could cause reflections to occur at high frequencies and is not a true measurement of the amplifier performance. 5) Set jumper J1 to the 1-2 position. 6) Set jumper J2 to the 1-2 position. 7) Set the power supply to ON 8) Connect a signal input to the DRIVER 1 INPUT BNC (J4). Each input connector on this EVM is terminated with a 50- resistor to ground. With a 50- source impedance, the voltage seen by the THS6012 amplifier IC on the EVM will be 1/2 the source signal voltage applied to the EVM input connector. 9) Verify the output signal on the oscilloscope. With a high-impedance scope probe, the output signal should be twice the source amplitude. When connected to J7 (Driver 2 output), the signal should be 180 phase shifted from the Driver 1 output (J5).
1-6
General Information
THS6012 EVM Performance
1.6 THS6012 EVM Performance
Figure 1-4 shows the typical frequency response of the THS6012 EVM drivers when properly loaded. This data was collected using a single-ended input with a 50- differential load connected between the driver outputs, as shown in the test circuit of Figure 1-5. Typical unity gain bandwidth with a 15 V power supply is 100 MHz for both drivers. With a 5 V power supply, typical unity gain bandwidth is also 100 MHz for both drivers. The difference between the output signals of driver 1 and driver 2 is primarily due to the high-frequency characteristics of the inverting amplifier (U1). Component values can be changed to cause the two responses to track more closely, but since ADSL signals are limited to 2 MHz and below, the high-frequency imbalance can usually be ignored.
Figure 1-4. THS6012 EVM Driver Frequency Response With a 50- Load
OUTPUT LEVEL vs FREQUENCY
7 Driver 2 Ouput 6 5 Output Level - dB 4 3 2 1 0 -1 -2 VCC = 5V VI(PP) = 2 V RL = 50 Differential JP1 : 1-2 JP2 : 1-2 1M 100M 10M f - Frequency - Hz 500M Driver 1 Input Output Level - dB 6 5 4 3 2 1 0 -1 -2 VCC = 15V VI(PP) = 2 V RL = 50 Differential JP1 : 1-2 JP2 : 1-2 1M 100M 10M f - Frequency - Hz 500M Driver 1 Input 7 Driver 2 Ouput
OUTPUT LEVEL vs FREQUENCY
-3 100k
-3 100k
Figure 1-5. THS6012 EVM Driver Frequency Response Test Circuit
1 OUT Pad 1 R8 12.4
Driver 1 Output
J5
GND
RL User Pad Area 25 Driver 2 Output 2 OUT Pad 2 R15 12.4 J7
General Information
1-7
General High-Speed Amplifier Design Considerations
1.7 General High-Speed Amplifier Design Considerations
The THS6012 EVM layout has been designed and optimized for use with high-speed signals and can be used as an example when designing THS6012 applications. Careful attention has been given to component selection, grounding, power supply bypassing, and signal path layout. Disregard of these basic design considerations could result in less than optimum performance of the THS6012 500-mA dual differential line driver IC. Surface-mount components were selected because of the extremely low lead inductance associated with this technology. Also, because surface-mount components are physically small, the layout can be very compact. This helps minimize both stray inductance and capacitance. Tantalum power supply bypass capacitors (C1 and C8) at the power input pads help supply currents for rapid, large signal changes at the amplifier output. The 0.1 F power supply bypass capacitors (C2, C3, C5, and C7) are placed as close as possible to the IC power input pins in order to keep the PCB trace inductance to a minimum. This improves high-frequency bypassing and reduces harmonic distortion. Additional 0.1 F capacitors (C13 and C14) are placed between +VCC and -VCC. This helps minimize the harmonic distortion of the amplifiers. A proper ground plane should always be used with high-speed circuit design. This provides low-inductive ground connections for return current paths. Special attention is needed for the inverting input pins. Stray capacitance at these pins can seriously degrade the performance of the amplifiers. In addition, ground plane coupling into these pins can cause noise to appear at the outputs of the amplifiers. This is especially important for the inverting pin while the amplifier is operating in the noninverting mode. Because the voltage at this pin swings directly with the noninverting input voltage, any stray capacitance would allow currents to flow into the ground plane, causing possible gain error and/or oscillation. Capacitance variations at the amplifier IC input pin of less than 1 pF can significantly affect the response of the amplifier. In general, it is always best to keep signal lines as short and as straight as possible. Sharp 90_ corners should generally be avoided -- round corners or a series of 45_ bends should be used, instead. Stripline techniques should also be incorporated when signal lines are greater than 3 inches in length. These traces should be designed with a characteristic impedance of either 50 or 75 , as required by the application. Such signal lines should also be properly terminated with an appropriate resistor. Finally, proper termination of all inputs and outputs should be incorporated into the layout. Unterminated lines, such as coaxial cable, can appear to be a reactive load to the amplifier IC. By terminating a transmission line with its characteristic impedance, the amplifier's load then appears to be purely resistive, and reflections are absorbed at each end of the line. Another advantage of using an output termination resistor is that capacitive loads are isolated from the amplifier output. This isolation helps minimize the reduction in amplifier phase-margin and improves the amplifier stability for improved performance such as reduced peaking and settling times.
1-8
General Information
General PowerPAD Design Considerations
1.8 General PowerPAD Design Considerations
The THS6012 IC is mounted in a special package incorporating a thermal pad that transfers heat from the IC die directly to the PCB. The PowerPAD package is constructed using a downset leadframe. The die is mounted on the leadframe but is electrically isolated from it. The bottom surface of the lead frame is exposed as a metal thermal pad on the underside of the package and makes physical contact with the PCB. Because this thermal pad is in direct physical contact with both the die and the PCB, excellent thermal performance can be achieved by providing a good thermal path away from the thermal pad mounting point on the PCB. Although there are many ways to properly heatsink this device, the following steps illustrate the recommended approach as used on the THS6012 EVM, which is built on a multilayer PCB with an internal ground plane. 1) Prepare the PCB with a top side etch pattern as shown in Figure 1-6. There should be etch for the leads as well as etch for the thermal pad.
Figure 1-6. PowerPAD PCB Etch and Via Pattern - Minimum Requirements
Thermal pad area (0.19 x 0.21) with 18 vias (Via diameter = 13 mils)
2) Place 18 holes in the area of the thermal pad. These holes should be 13 mils in diameter. They are kept small so that solder wicking through the holes is not a problem during reflow. 3) Additional vias may be placed anywhere along the thermal plane outside of the thermal pad area. This will help dissipate the heat generated from the THS6012. These additional vias may be larger than the 13 mil diameter vias directly under the thermal pad. They can be larger because they are not in the thermal-pad area to be soldered, therefore, wicking is generally not a problem. 4) Connect all holes to the internal ground plane. 5) When connecting these holes to the ground plane, DO NOT use the typical web or spoke via connection methodology. Web connections have a high thermal resistance connection that is useful for slowing the heat transfer during soldering operations. This makes the soldering of vias that have plane connections easier. However, in this application, low thermal resistance is desired for the most efficient heat transfer. Therefore, the holes under the THS6012 package should make their connection to the internal ground plane with a complete connection around the entire circumference of the plated through hole.
General Information
1-9
General PowerPAD Design Considerations
6) The top-side solder mask should leave exposed the terminals of the package and the thermal pad area with its 18 holes. The bottom-side solder mask should cover the 18 holes of the thermal pad area. This eliminates the solder from being pulled away from the thermal pad area during the reflow process. 7) Apply solder paste to the exposed thermal pad area and all of the operational amplifier terminals. 8) With these preparatory steps in place, the THS6012 is simply placed in position and run through the solder reflow operation as any standard surface mount component. This results in a part that is properly installed. The actual thermal performance achieved with the THS6012 in its PowerPAD package depends on the application. In the example above, if the size of the internal ground plane is approximately 3 inches x 3 inches, then the expected thermal coefficient, JA, is about 21.5_C/W. For a given JA, the maximum power dissipation, shown in Figure 1-7, is calculated by the following formula:
P Where:
D
+
T
MAX
-T
q JA
A
PD = Maximum power dissipation of THS6012 (watts) TMAX = Absolute maximum junction temperature (150C) TA = Free-ambient air temperature (C) JA = JC + CA JC = Thermal coefficient from junction to case ( 0.37C/W) CA = Thermal coefficient from case to ambient air
Figure 1-7. Maximum Power Dissipation vs. Free-Air Temperature
MAXIMUM POWER DISSIPATION vs FREE-AIR TEMPERATURE
9 8 Maximum Power Dissipation - W 7 6 5 4 3 2 1 0 -40 -20 0 20 40 60 80 100 JA = 21.5C/W 2 oz Trace and Copper Pad with Solder Tj = 150C PCB Size = 3" x 3" No Air Flow
JA = 43.9C/W 2 oz Trace and Copper Pad without Solder
TA - Free-Air Temperature - C
1-10
General Information
General PowerPAD Design Considerations
Even though the THS6012 EVM PCB is larger than the one in the example above, the results should correlate very well because the traces and the vias of the EVM PCB interrupt the thermal continuity of the ground plane. The THS6012 EVM is a good example of proper thermal management when using PowerPAD-mounted devices. Correct PCB layout and manufacturing techniques are critical for achieving adequate transfer of heat away from the PowerPAD IC package. More details on proper board layout can be found in the THS6012 500-mA DUAL DIFFERENTIAL LINE DRIVER data sheet (SLOS226). For more general information on the PowerPAD package and its thermal characteristics, see the Texas Instruments Technical Brief, PowerPAD Thermally Enhanced Package (SLMA002).
General Information
1-11
1-12
General Information
Chapter 2
Reference
This chapter includes a parts list and PCB layout illustrations for the THS6012 EVM.
Topic
2.1 2.2
Page
THS6012 Dual Differential Line Drivers and Receivers EVM Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 THS6012 EVM Board Layouts
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Reference
2-1
THS6012 Dual Differential Line Drivers EVM Parts List
2.1 THS6012 Dual Differential Line Drivers EVM Parts List
Table 2-1. THS6012 EVM Parts List
Reference C1, C8 C2, C3, C5, C7, C9, C10, C13, C14 L1,L2 J4,J5,J6, J7 J1,J2,J3 JP1,JP2 R2, R9 R1, R10 R3, R4, R5, R6, R12, R13 R8, R15 U2 U1 R7, R14 R11 C4, C6, C11, C12 Description CAPACITOR, 6.8 F, 35 V, 20%, TANTALUM, SM CAPACITOR, 0.1 F, CERAMIC, 10%, SM 0805 Size Quantity 2 8 Manufacturer/Distributor Part Number (SPRAGUE) 293D685X9035D2T (MuRate) GRM40-X7R104K25
INDUCTOR, 0.22 H AXIAL, THRU HOLE JACK, BNC, PC-MOUNT (AMPHONEL) JACK, BANANA RECEPTANCE, FOR 0.25 DIA. HOLE HEADER, 3 PIN, 0.1 CTRS., 0.025 SQ. PINS RESISTOR, 49.9 OHMS, 1/10W, 1% SM RESISTOR, 49.9 OHMS, 1/8W, 1% SM RESISTOR, 1 kOHM, 1/10W, 1% SM RESISTOR, 12.4 OHMS, 1/8W, 1% SM IC, THS6012CDWP IC, OP AMP, THS4001CD RESISTOR, X OHMS, 1/8W, 1%, SM RESISTOR, X OHMS, 1/10W, 1%, SM CAPACITOR, X F, 10% CERAMIC 4-40 TREAD HEX STANDOFFS, 0.625 LENGTH, 0.250 O.D. 4-40 TREAD HEX STANDOFFS SCREWS SOIC-8 1206 0805 0805 0805 1206 0805 1206
2 4 2 2 2 4 6 2 1 1 2 1 4 4 4
(DELEVAN) DN41221/ (DIGI-KEY) DN411221-ND (MOUSER) 523-31-5329
(TI) THS6012CDWP (TI) THS4001CD
(MOUSER) 534-1804
PCB1 PCB, THS6012 EVM SLOP132 1 The values of these components are to be determined by the user in accordance with the application requirements.
2-2
Reference
THS6012 EVM Board Layouts
2.2 THS6012 EVM Board Layouts
Board layout examples of the THS6012 EVM PCB are shown in the following illustrations. They are not to scale and appear here only as a reference.
Figure 2-1. THS6012 EVM Component Placement Silkscreen and Layout
+VCC J1 J2 GND J3 -VCC
L1 +
C1
C8
L2
R7 R8 C2 13
Driver 1 Input
J4 R1 R2 C4 C3
U2 C10 R3 R11 R12 Pad1 GND Pad2
R5 C6 R6
U1
R4 C11 C5
JP1 C7 Driver 2 Input J6
JP2 R10
C12 R13 R14 R15
R9
14 C9
+
J5
Driver 1 Output
Texas Instruments THS6012 EVM SLOP132 Rev. B
J7
Driver 2 Output
Figure 2-2. THS6012 EVM PC Board: Layer 1 -- Top Side Layout
Reference
2-3
THS6012 EVM Board Layouts
Figure 2-3. THS6012 EVM PC Board: Layer 2 -- Back Side Ground Plane Layer
Figure 2-4. THS6012 EVM PC Board: Solder Mask -- Back Side
2-4
Reference

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