Page 21 - Chip Scale Review_November-December_2023-digital

Automotive gate driver package with galvanically-

isolated communication linkage

By Ankur Shah, Burton Carpenter, Fred Brauchler, Di Liu, Pierre Calmes, JM Liu, Xueting Wu [NXP Semiconductors, Inc.]
W ith legislation driving to Council (AEC) Q100 Grade 1 component Meanwhile, the HV leads connect to

reduce CO 2 emissions,
electric vehicles (EVs) reliability requirements, including AEC the 400V~800V battery that powers
the drivetrain motors. For safety and
Q006 Cu wire criteria.
are a perfect alternative to internal functional reasons, the package must
combustion engine (ICE) vehicles and Galvanic isolation maintain galvanic isolation between the
government incentives are encouraging Galvanic isolation is the principle of LV and HV domains. Functional safety
faster adoption from ICE vehicles to isolating functional sections of electrical requirements for the gate drivers is at
EVs. Approximately half of all vehicles systems to prevent current flow—no Automotive Safety Integrity Level D
sold by 2030 will contain an electrified direct conduction path is permitted. (ASIL-D).
powertrain [1]. Furthermore, vehicle However, energy or information can The development and release of
electrification is driving advanced still be exchanged between the sections this gate driver package occurred in
functional safety, control and protection by other means, such as capacitive, two phases. A summary for the initial
features in automotive EV electronics. inductive (magnetic), optical, acoustic or 7.72mm creepage automotive drivetrain
Many on-board systems such as EV mechanical coupling. Furthermore, the appl icat ion wa s su m m a r i ze d by
traction inverters, DC/DC converters, device must meet certain performance Carpenter, et al. [2]. This paper provides
and on-board chargers are powered by, c r it e r i a a nd p a s s A E C G r a d e 1 an overview of the upgraded package
or connected to, high-voltage power component qualification for under-the- with greater creepage, enhanced design
sources. For example, a traction inverter hood operation. criteria, and improved HV performance:
converts DC voltage from a high-voltage An advanced gate driver package achieving a comparative tracking
battery into a high-current, multi-phase ma kes di rect physical elect r ical index (CTI) >600V (Material Group 1),
AC voltage to drive the traction motor. con nect ions to bot h H V a nd LV creepage >8mm, and common mode
Microcontroller unit (MCU) output is domains, therefore, safety and functional transient immunity (CMTI) >200V/nsec.
not capable of driving a power device requirements necessitate that design,
(insulated-gate bipolar transistor [IGBT] testing and manufacture of the gate driver Product features
or silicon carbide [SiC]), which in turn component ensure galvanic isolation NXP’s gate driver IC (GDIC) is
drives the traction motor. Therefore, to between these domains. functionally safe (ASIL C/D compliant)
drive the power device, an isolated gate In a typical application as shown in and can be used with both 400V
driver is essential because of features Figure 1, the gate driver is electrically and 800V traction inverter systems.
such as a strong gate drive and overshoot connected to two isolated voltage T hese new isolated GDICs have
protection; additionally, faster switching domains, termed LV and HV. The LV features optimized for operation with
allows for higher efficiency, faster reverse leads connect to the automobile control both IGBT and SiC power devices.
recovery, and lower input capacitance, etc. system powered by the 12V~ 48V These features include dynamic gate
A 32-lead small outline integrated battery grounded to the vehicle chassis. strength control (+/-10A to +/-30A)
circuit (SOIC) package with leads on
only two sides was selected to meet the
creepage and clearance requirements.
Internal isolation was achieved by placing
a high-voltage dielectric barrier between
two stacked die that could communicate
by inductive (magnetic) coupling.
Galvanic isolation, therefore, was achieved
between the high voltage (HV) and low
voltage (LV) sides, thereby meeting
the UL 1577 requirement for 5000V rms
isolation for 60 seconds. Accelerated
lifetime tests confirmed working voltages
up to 1500V pk can be maintained for at
least 20 years. Finally, the package passed
the full suite of Automotive Electronics Figure 1: Schematic of gate driver application.

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