7

PCB, BOM, and layout recommendations

7.1

PCB suggestions

This section lists some tips to facilitate the PCB routing of the STDRIVEG611.

7.1.1

External BOM values selection and placement

A list of recommended value ranges for some key components are reported.

The bulk capacitors required for VCC, VCCL, VCCH, and BOOT must be placed as close as possible to relevant

pins and relevant references. Such capacitors must be low ESR/ESL ceramic components having rated voltages

that are almost twice the maximum operating voltages to overcome the well-known value modulation versus bias

voltage.

The eventual external bootstrap diode is typically not required in motor control applications but is possible. In case

of external diode use, a series resistor with a value of ≥ 2.2 Ω (10 Ω in case of large CBOOT) is recommended to

minimize the bootstrap diode peak current, EMI generation and supply rail spike generation. In case an external

bootstrap diode is used, the CBOOT capacitor must be placed on the PCB in such a way that the negative terminal

is put as close as possible to the OUT pin: this arrangement ensures that the charging current flows in the

shortest track possible. In the case of overcurrent comparator use, the user should consider the bootstrap current

sums with the load current through the low-side: undesired overcurrent events could be generated especially with

low RBOOT values.

Turn-on resistors (RONx) need to be placed close to the IC to minimize the length of the track connected to the

RONx pin.

Table 7. External BOM summary

Symbol Function

Value (range)

Technology

Min. rating

CVCC

VCC large bulk capacitor (it is normally used as bulk capacitor of

controller too)

2.2 to 10 µF

EL-Cap (or X7R)

25 V

VCC bypass capacitor

100 nF

X7R

50 V

CBOOT BOOT to OUT bypass capacitor

CVCCH to 3300 nF

X7R

50 V

CVCCL VCCL to PGND bypass capacitor

47 nF to 470 nF

X7R

16 V

CVCCH VCCH to OUT bypass capacitor

47 nF to 470 nF

X7R

16 V

RBOOT Current limiting resistor of external DBOOT

≥ 2.2 Ω

DBOOT

External Bootstrap diode (typically not required in motor control

applications)

STTH1R06 or

equivalent

Turbofast

600 V / 1 A

To speed-up start-up time, the user shall minimize CBOOT and CVCCH values. Most power conversion applications

are optimized using CBOOT = CVCCx = 47 nF. Most motor control applications (depending on gate load) are

optimized when using CVCCx = 47 to 100 nF and CBOOT = 100 to 470 nF.

A larger CBOOT capacitor could be rarely required in specific applications if a very long high side on-time is

required. On all other applications is recommended to keep CBOOT small to avoid increasing start-up time, the

potential need of the additional external bootstrap diode, the diode dissipation. In extreme cases, as in all gate

driver applications, excessive CBOOT and small CVCC can lead to VCC drops due to charge sharing when low-

side turns on, detected by the VCC UVLO.

PGND must be connected to the low-side GaN (Kelvin if available) source, which creates the path to GND

through the optional current shunt resistor. So, PGND shall not be directly connected to GND to avoid shorting the

Kelvin connection and reducing its benefits.

OUT must be connected to the high-side GaN (Kelvin if available) source. GaN main source and Kelvin source

shall not be shorted together externally to best exploit the Kelvin benefits.

VCCL and VCCH are the output access to the internal voltage regulator: forcing these pins to external voltage

regulators may result in unrecoverable damage of the IC.

STDRIVEG611

PCB, BOM, and layout recommendations

DS14457 - Rev 2

page 22/33