IC-RC1000_14 Datasheet, PDF (2/14 Pages) IC-Haus GmbH – SIN/COS SIGNAL SAFETY MONITOR IC

iC-RC1000
SIN/COS SIGNAL SAFETY MONITOR IC
Rev C2, Page 2/14
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). Single-ended signals referenced to ground
with twice this amplitude (400 to 600 mV) can also
be monitored; here, the negative input must be kept
within the permissible DC range (e.g. VCC/2).
iC-RC1000 has intrinsic safety, enabling single er-
rors to be securely identified through redundancy;
independent of one another, two different diagnostic
channels monitor the input signals, and output sepa-
rate messages.
iC-RC1000 confirms valid input signals by a signal
OK message of OK = 1 and a signal error message
of ERR = 0.
iC-RC1000 confirms invalid input signals by a signal
OK message of OK = 0 and a signal error message
of ERR = 1.
If the messages are not complementary to one an-
other, the inputs signals are at range limits or a circuit
error does exist.
Each diagnostic channel has signal comparators
for DC and square sum monitoring; the monitoring
windows have different designs depending on the
good/bad diagnosis.
The square sum monitor uses an analog multiplier
and evaluates the Lissajous figure derived from the
square signal of sine and cosine (sin(wt)² + cos(wt)²).
In order for the external controller to safely detect an
interrupt, the status times are extended to at least
4 ms by retriggerable monoflops. After power-on iC-
RC1000 starts in signal error status, and sets the sig-
nal OK status at the earliest after the monoflop period
has elapsed. The status outputs are configured as
push-pull drivers so that optocouplers can be directly
connected up to the device (10 mA low side, 4 mA
high side).
The front end signal splitter isolates the two diag-
nostic channels from one another. The integrated
clamping circuit then reduces the input voltage to a
value within the permissible range (supply voltage)
and protects against overvoltage with the help of ex-
ternal resistors (18 kΩ at each signal input). At the
same time this decouples the signal source so that a
controller can simulate an error by loading an input
pin. For the detection of signal losses, caused by a
fractured cable for instance, integrated pull-down re-
sistors (2.5 MΩ) drag the DC potential into the error
range.
iC-RC1000 works at a supply voltage of 5 V. The di-
agnostic channels can be supplied by one or two sep-
arate voltage sources and mutually monitor the ap-
plied supply voltages on undervoltage. The device
is protected against ESD and in the given circuit is
overvoltage-proof at the front end up to 36 V.