General PowerPAD Design Considerations | Texas Instruments THS4012

General PowerPAD Design Considerations

1.12 General PowerPAD Design Considerations

The THS4012DGN 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 THS4012 EVM.

1)Prepare the PCB with a top side etch pattern as shown in Figure 1±8. There should be etch for the leads as well as etch for the thermal pad.

Figure 1±8. PowerPAD PCB Etch and Via Pattern

Thermal pad area (68 mils x 70 mils) with 5 vias

(Via diameter = 13 mils)

2)Place five 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 helps dissipate the heat generated by the THS4012DGN IC. 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 so that wicking is 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. In this application, however, low thermal resistance is desired for the most efficient heat transfer. Therefore, the holes under the THS4012DGN package should make their connection to the internal ground plane with a complete connection around the entire circumference of the plated-through hole.

6)The top-side solder mask should leave the terminals of the package and the thermal pad area with its five holes exposed. The bottom-side solder mask should cover the five holes of the thermal pad area. This prevents 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 IC terminals.

General 1-17

THS4012 specifications

The Texas Instruments THS4012 is a high-performance, dual-channel operational amplifier designed for a wide variety of applications requiring high speed and precision. This op-amp is particularly appreciated in the fields of signal processing, data acquisition, and instrumentation, thanks to its exceptional characteristics and innovative technologies.

One of the standout features of the THS4012 is its ultra-low input noise and high slew rate, which make it a compelling choice for applications that demand rapid response times without signal distortion. With a slew rate of up to 1200 V/µs, the THS4012 can handle rapid changes in input signals, making it ideal for high-frequency applications such as analog-to-digital converters and RF signal processing.

In terms of performance, the THS4012 boasts a wide bandwidth of approximately 100 MHz at a gain of 1, ensuring it can efficiently transmit fast signals without significant loss. The part also provides a high common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR), enhancing its stability in environments with fluctuating power supply conditions or varying signal levels.

Another important aspect of the THS4012 is its low total harmonic distortion (THD), which is crucial for high-fidelity applications. By minimizing distortions, it ensures that the output signal closely matches the input signal, preserving the integrity of the original waveform. This makes it especially suitable for audio applications and precision data acquisition systems.

The THS4012 operates on a single or dual power supply, with a voltage range from ±2.5 V to ±6 V, providing designers with the flexibility to integrate this op-amp into various circuit configurations. The device is available in compact packages, making it suitable for space-constrained designs in portable electronics.

Additionally, the THS4012 incorporates innovative features such as internal compensation, which simplifies the design process by reducing the need for external components. This enhances design efficiency and reliability, allowing engineers to focus on other critical aspects of their circuits.

In conclusion, the Texas Instruments THS4012 dual operational amplifier combines high-speed performance, low distortion, and flexible power supply options, making it a popular choice for engineers looking to enhance the capabilities of their electronic systems. Its advanced technologies and characteristics render it a strong option in a myriad of applications within today's demanding electronic landscape.