AMIS-30624 Datasheet, PDF (5/56 Pages) AMI SEMICONDUCTOR – I2C Microstepping Motordriver

AMIS-30624
8.0 Package Thermal Resistance
8.1 SOIC-20
To lower the junction-to-ambient thermal resistance, it is recommended to connect the ground leads to a printed circuit board (PCB)
ground plane layout as illustrated in Figure 3. The junction-to-case thermal resistance is dependent on the copper area, copper
thickness, PCB thickness and number of copper layers. Calculating with a total area of 460 mm², 35µm copper thickness, 1.6mm PCB
thickness and 1 layer, the thermal resistance is 28°C/W; leading to a junction-ambient thermal resistance of 63°C/W.
PC20041128.1
Figure 3: PCB Ground Plane Layout Condition
8.2 NQFP-32
The NQFP is designed to provide superior thermal performance, and using an exposed die pad on the bottom surface of the package
partly contributes to this. In order to take full advantage of this thermal performance, the PCB must have features to conduct heat away
from the package. A thermal grounded pad with thermal vias can achieve this. With a layout as shown in Figure 4, the thermal
resistance junction – to – ambient can be brought down to a level of 25°C/W.
NQFP-32
PC20041128.2
Figure 4: PCB Ground Plane Layout Condition
Rev. 4 | Page 5 of 56 | www.onsemi.com