IC-RC1000 Datasheet, PDF (2/10 Pages) IC-Haus GmbH – SIN/COS SIGNAL SAFETY MONITOR IC

iC-RC1000
preliminary
SIN/COS SIGNAL SAFETY MONITOR IC
Rev A2, Page 2/10
DESCRIPTION
iC-RC1000 acts as an independent monitoring de-
vice for industrial safety controllers and drive systems
in the evaluation of sine encoders for SIL applica-
tions.
In this function the IC checks that four analog signal
lines have the correct DC voltage range (DC range:
30 to 80 % from VCC1 or VCC2) and that two respec-
tive paired lines have the correct differential 1 Vpp
signal amplitude in real time (amplitude range: 200
to 300 mV). Signals with twice this amplitude (400 to
600 mV) referenced to ground can also be monitored;
here, the negative input must be kept within the per-
missible DC range (e.g. VCC/2).
iC-RC1000 has intrinsic safety, enabling single er-
rors to be securely identified through redundancy; in-
dependently of one another, two different diagnostic
channels monitor the input signals, outputting sepa-
rate messages. The Signal OK and the Signal er-
ror statuses are complementary to one another if the
chip is functioning correctly.
So that the external controller can safely detect an
interrupt, the status times are extended to at least
10 ms by retriggerable monoflops. After power on iC-
RC1000 starts in Signal error status, setting the Sig-
nal OK status at the earliest after the monoflop pe-
riod has elapsed. The status outputs are configured
as push-pull drivers so that optocouplers can be di-
rectly connected up to the device (10 mA low side,
4 mA high side).
The front end signal splitter isolates the two diagnos-
tic channels from one another and provides protec-
tion against overvoltage with the help of external re-
sistors (39 kΩ at each signal input). The integrated
clamp circuit then reduces the input voltage to within
the permissible range. At the same time this de-
couples the signal source so that a controller can
simulate an error by loading an input pin. So that
signal failures can be detected should there be a
fractured cable, for example, integrated pull-down re-
sistors (2.5 MΩ) drag the DC potential into the error
range.
Each diagnostic channel has signal comparators
for DC and square sum monitoring; the monitoring
windows have a different design depending on the
good/bad diagnosis. The square sum monitor uses
an analog multiplier and calculates the Lissajous
curve derived from the square signal by the sine and
cosine (sin(wt)² + cos(wt)²).
iC-RC1000 works with a supply voltage of 5 V. The
diagnostic channels can be supplied by one or two
separate power packs and mutually monitor the ap-
plied supply voltage. The device is protected against
ESD and in the given circuit is overvoltage-proof at
the front end up to 36 V.