n
When technical equipment fails, more often
than not finding the root cause of the problem
consumes significantly more time than actually
fixing it. In highly sophisticated factory au-
tomation environments where capital intensive
equipment is in operation, or where time-cou-
pled chemical processes are at work, line-
downs can have substantial implications on
the commercial viability of the enterprise.
Therefore, the days of machinery providing
no diagnostic feedback are becoming obsolete.
Solutions that can provide intelligent diagnostic
feedback as the system is beginning to fail
(preventive maintenance), or when a hard
failure has occurred (repair), are key to reducing
expensive unscheduled down-times.
The ISO2H823V is an 8-channel high-side
driver IC that features integrated 2.5kVrms
galvanic isolation, which exceeds the IEC 61131-2
requirements for reinforced isolation. Concur-
rently, it sets a new standard for system-level
diagnostics. Each of the 8 channels is equipped
with five-fold diagnostic monitoring capabili-
ties: open load active, open load inactive, short-
to-Vbb, overcurrent and overtemperature.
Additionally five types of diagnostic feedback
on the IC-level are provided. This is all inte-
grated into a small 12 x 12 mmVQFN package.
In the industrial control system, thanks to the
integrated galvanic isolation, the device is
positioned between the 3.3V microcontroller
domain (control side) and the 24V factory
floor domain (process side). The most frequent
failure mechanisms on the application level
include overload of the driver outputs or actu-
ally having no load (open load) connected to
the driver outputs. Another severe deficiency
is lack of or insufficient supply of the 24Vbb
on the factory side of the system. The
ISO2H823V can detect either of these problems
and many more. This capability is highly valu-
able for OEMs to prompt preventive mainte-
nance, and in case of malfunctions to drastically
reduce the time required for repair. The great
benefit for the system designer rests on the
fact that many powerful diagnostic capabilities
are available in the single IC. This eliminates
the need to develop complex and potentially
cumbersome circuit layouts based on multiple
discrete components, to be able to perform di-
agnostic monitoring. In consequence, system
design efforts, risks and time are reduced sub-
stantially, PCB area can be kept small, and the
reliability of the solution is not compromised.
As already mentioned there are five types of
diagnostics for each individual channel.
Overload [OCL]: Wear-out of machinery may
lead to an output overload. In its extreme
form there is actually a short circuit to GND
caused by erroneous wiring, or a short circuit
during operation, or a natural disaster which
leaves the equipment flooded, i.e. it is literally
under water. The device can detect such cases.
When a channel switch is on, that channel
output current is monitored. If the output
current exceeds the threshold to activate the
current limitation, typically set at 1A, then
overcurrent limitation (OCL) is flagged to the
microcontroller. Unlike other products, the
ISO2H823V provides not only overload feed-
back, but it also informs the system controller
which channel is subjected to the overload.
This information can be instrumental in iden-
tifying the root cause, which is critical to
getting the system back on line within the
shortest time possible.
Open load [OLA]: Mechanical strain, e.g. vi-
bration or excessive bend stress of a cable, as
well as corrosion can lead to the wiring between
the IC switching output and the load becoming
high-ohmic or even disconnected (wire-break).
The power management device can detect
such circumstances. The IC performs output
current monitoring, and not only for the pur-
pose of limiting the maximum output current.
The same capability is used to detect no-load
situations. An open load active (OLA) feedback
is provided if an output is turned on and the
output current of an individual channel is less
than 0.5mA to 3mA. The system hardware de-
sign has the freedom to set the triggering
threshold level within this range. No other
driver product designed for the industrial con-
Intelligent diagnostics maximize
factory-floor up-times
P
OWER
M
ANAGEMENT
By Hubert Baierl,
Infineon Technologies
This article introduces
the ISO2H823V, a power
management integrated
circuit with built-in intelligent
diagnostic functions designed
for a wide range of
industrial control applications,
including programmable
logic controllers (PLCs),
distributed control systems,
robotics and many more.
April 2014
24
Figure1. The ISO2H823V
is a power management
integrated circuit setting a
new standard for system-
level diagnostics in a tiny
12 x 12 mm VQFN package
