SLUU130A – September 2002 – Revised February 2003

5 PowerPADPackaging

The TPS4000X family is available in the DGQ version of TI’s PowerPADthermally enhanced package. In the PowerPAD, a thermally conductive epoxy is utilized to attach the integrated circuit die to the leadframe die pad, which is exposed on the bottom of the completed package. The leadframe die pad can be soldered to the PCB using standard solder flow techniques when maximum heat dissipation is required. However, depending on power dissipation requirements, the PowerPADmay not need to soldered to the PCB.

The PowerPADpackage helps to keep the junction temperature rise relatively low even with the power dissipation inherent in the onboard MOSFET drivers. This power loss is proportional to switching frequency, drive voltage, and the gate charge needed to enhance the N-channel MOSFETs. Effective heat removal allows the use of ultra small packaging while maintaining high component reliability.

To effectively remove heat from the PowerPADpackage, a thermal land should be provided directly underneath the package whether the package needs to be soldered or not. This thermal land usually has vias that help to spread heat to internal copper layers and/or the opposite side of the PCB. The vias should not have thermal reliefs that are often used on ground planes, because this reduces the copper area which transfers heat. Additionally, the vias should be small enough so that the holes are effectively plugged when plated. This prevents the solder from wicking away from the connection between the PCB surface and the bottom of the part. A typical construction utilizes a few vias of 0.013” diameter plated with 1 ounce copper in the land under the TPS40003. A typical layout pattern is shown in Figure 2, but does not show the copper land which would encompass the vias above and below the device.

2.92mm

(0.115”)

0.5mm

(0.0197”)

Minimum

PowerPad ”Y” 1.7mm (0.068”)

0.28mm

1.40mm

Via Dia.

(0.055”)

(0.011”)

 

0.33mm

 

 

(0.013”)

Miminum

PowerPad ”X”

1.3mm

(0.050”)

Figure 3. PowerPAD PCB Layout Guidelines

The Texas Instrument document, PowerPADThermally Enhanced Package Application Report (SLMA002) should be consulted for more information on the PowerPADpackage. This report offers in-depth information on the package, assembly and rework techniques, and illustrative examples of the thermal performance of the PowerPADpackage.

10TPS40003-Based 5-A Converter in Less Than One Square Inch

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Texas Instruments TPS40003 manual PowerPAD Packaging, PowerPAD PCB Layout Guidelines
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TPS40003 specifications

The Texas Instruments TPS40003 is a versatile, high-performance synchronous buck controller designed to efficiently regulate output voltage in a range of applications. This device is particularly suited for power supply designs where space and efficiency are critical, such as telecommunications, industrial automation, and consumer electronics.

One of the standout features of the TPS40003 is its ability to operate over a wide input voltage range of 4.5V to 36V. This flexibility allows it to be effectively utilized in various scenarios, accommodating different power supply systems and ensuring compatibility with existing infrastructure. Furthermore, the output voltage can be adjusted down to as low as 0.8V, making it suitable for powering low-voltage microcontrollers and FPGAs.

The TPS40003 incorporates advanced voltage mode control, which enhances transient response and stability. This control method allows for quick adjustments in duty cycle in response to load changes, ensuring a steady output voltage even under varying loads. Coupled with a programmable soft-start feature, the controller minimizes inrush current during startup, protecting sensitive downstream components.

Another significant advantage of the TPS40003 is its integration of a high-side and low-side MOSFET driver. This synchronous operation significantly improves power efficiency by reducing conduction losses. The device operates with a high switching frequency, typically around 200 kHz, allowing for the use of smaller passive components and ultimately leading to a more compact design.

Thermal performance is another essential characteristic of the TPS40003. With built-in thermal shutdown and overcurrent protection features, it promotes reliable operation under various thermal conditions, enhancing the overall robustness of the power supply design. Additionally, the device's wide range of compensation options allows designers to fine-tune performance according to specific application requirements.

In terms of packaging, the TPS40003 is offered in a compact, thermally enhanced HTQFN package, which helps in conserving PCB space while maintaining efficient heat dissipation.

Overall, the Texas Instruments TPS40003 controller stands out as a robust, feature-rich solution for DC-DC conversion applications. With its wide operating voltage range, synchronous operation, and protective features, it provides designers with a reliable, efficient means of managing power in today's demanding electronic systems.
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