August 31, 2021 © 2021 Transphorm Inc. Subject to change without notice.
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Daughter cards for evaluating
Transphorm’s PQFN88 and
PQFN56 packaged devices in
TO-220 Sockets
1. Overview
This application note describes Transphorm’s (TPH)
TPHDC001 PQFN daughter card and its purpose. The
TPHDC001 can be used as a generic carrier to install and
evaluate current TPH PQFN 8x8 and PQFN 5x6 GaN devices
in existing Si evaluation boards that uses TO-220 Si
packages. The main driving point is to quickly observe the
performance of the TPH GaN technology in the different Si
based topologies or applications.
Transphorm’s PQFN (Power Quad Flatpack No Lead)
package incorporates a DPC (Direct Plated Cu) substrate
and a Cu lead frame encapsulated in a green molding
compound for bottom electrical connection and thermal
contact to the printed circuit board [1].
The most current TPH PQFN devices are listed in the
chart below.
TPH Product
TYPICAL Rdson
(mOhm)
PACKAGE TYPE
TP65H300G4LSG
300
PQFN88
TP65H150LSG
150
PQFN88
TP65H070LSG
72
PQFN88
TP65H480G4JSG
480
PQFN56
Chart 1. TPH PQFN devices
See the Transphorm website
https://www.transphormusa.com/en/products for the
detailed list and datasheets of Transphorm’s PQFN devices.
On behalf of the traditional Si-MOSFET, the metal tab of
the PQFN device is Drain, as the bottom of the die is always
the Drain terminal. For Transphorm’s GaN PQFN devices,
the metal tab is the Source terminal. GaN FETs have much
higher dv/dt switching speed. Refer to figure 1 and figure 2
for package representation.
Figure 1. TPH PQFN 8x8
Figure 2. TPH PQFN 5x6
2. Circuit Parameters and PCB Layout
The TPHDC001 daughter card makes it convenient for
Engineers to examine TPH GaN PQFN devices in their
existing TO-220 Si application designs.
The output terminals of this daughter-card carrier is
configured as GDS so that it can fit the common TO-220
socket design. See figure 3 for the TPHDC001 schematic
and figure 4 for the TPHDC001 PCB layout.
Figure 3. TPHDC001 Schematic
August 31, 2021 © 2021 Transphorm Inc. Subject to change without notice.
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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.
TPHDC001
Qty
Device
Parts
PN
1
R-US_R1206
SNR1
DNI
1
C-USC1206
SNC1
DNI
1
R-US_R0402
R1
RC0402FR-0749R9L
1
R-US_R0402
FB
BLM15AG121SH1D
1
GSD_TO220
P1
PRPC003SBAN-M71RC
1
TPH GaN
Q1
TPH GaN
Chart 2. TPHDC001 BOM.