August 31, 2021 © 2021 Transphorm Inc. Subject to change without notice.
AN0013
G D S
Figure 4. TPHDC001 PCB Layout (GDS output terminal)
The PCB specifications for the daughter card are below:
Dimension: 0.322in x 0.7389in
Thickness: 0.062in
2 layers - 1 ounce copper each layer
FR4 material
Footprints for Rg, FB, and Snubber are included
The exposed copper pads on figure 4 are designed to
accommodate the TPH PQFN 8x8 and 5x6 devices.
Transphorm offers a single landing pattern for both types of
PQFN devices offered. See figure 5 for the bottom side view
of the TPH PQFN devices.
Figure 5. Bottom views of TPH PQFN56 and PQFN88
Based on the LSG (8x8) and JSG (5x6) TPH PQFN
solutions, each package has a different assembly location
resulting in a 2
nd
source solution and an increase in
capacity. See figure 6 for the bottom view of assembly
location of the PQFN devices.
Figure 6. Device Landing Pattern
The PCB design also includes placements for Rg and
FB, incase those components are not already positioned on
the main driving circuit of the Si development board. These
devices may not be required depending on the layout.
The switching node snubber footprints are placed in
this daughter card for engineers to populate in order to
operate the TPH GaN devices in high current applications.
The TPH product datasheet describes in detail the
recommended driving circuit implementation for simplified
half bridge and single ended projects. Note that a gate
ferrite bead (FB) and the switching node snubber (SNR1 &
SNC1)may not be needed for single-end applications (Chart
2), such as ACF, QR Flyback, etc. Those components are
recommended for half-bridge circuit applications.
For single ended designs, by recommendation, do
not install (DNI) the switching node snubbers for low power
operation. See the chart below for the list of standard
installed components on TPHDC001. See figure 7 and
figure 8 for reference.
Chart 2. TPHDC001 BOM.