iC-RC1000
SIN/COS SIGNAL SAFETY MONITOR IC
preliminar y
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.
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
).
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.
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.
ICHAUS [ IC-HAUS GMBH ]
