ADS8638: Thermal Pad

user744376

Part Number: ADS8638

ADS8638 Thermal PAD

In the specification it is clear that the Thermal Pad must be soldered to the PCB.

From the specification it is unclear to me where to connect the Thermal Pad electrical potential or should it just be electrical floating.

Regards

Jorgen

over 5 years ago

0 Dale Li over 5 years ago

TI__Mastermind 39805 points

Hi Jorgen,

The thermal pad should be connected to the solid ground plane, please see the layout recommendation in Figure 97 and 98 in ADS8638 datasheet.

Regards,

Dale

0 user744376 over 5 years ago in reply to Dale Li

Intellectual 420 points

Hi Dale,

Sorry I do not see the direct solid connection to ground plane form the IC PAD in Figure 97 and 98:

For me it looks like TOP PAD NOT is connected to the 9 VIA in the PAD = Bad thermal contact?

The TOP PAD is connected to pin 2, 3, 5 and 20.

Only 3 and 20 are connection connected to GND with only two plated holes?.

Please comment

/Jorgen

0 user744376 over 5 years ago in reply to user744376

Intellectual 420 points

ADS8638 12bit 8CH BI-POLAR FSR +-10, 10V, 5, 2.5V 2.6-3.00usd_JML191113.pdfNow with attachment, please see figure 97+98

0 Dale Li over 5 years ago in reply to user744376

TI__Mastermind 39805 points

Hi Jorgen,

I apologized for the confusion to you. You are right and the vias shown in Figure 98 of datasheet are not connected to the ground on the bottom layer. However, the ADS8638EVM shows the pad under the device is connected the ground plane with three vias, I also measured them to verify on real EVM board. The exposed thermal pad should be soldered to the PCB as an integrated heat sink. In most applications, the exposed pad is connected to the ground plane with multiple vias thus creating a low-impedance path to dissipate the thermal energy.

Regards,

Dale

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ADS8638: Thermal Pad