Rainbow Electronics U3741BM - Manual (Page 16)

16
U3741BM
4662B–RKE–10/04
Figure 14. Synchronization of the Demodulator Output
Figure 15. Debouncing of the Demodulator Output
Figure 16. Steady L State Limited DATA Output Pattern after Transmission
After the end of a data transmission, the receiver remains active and random noise
pulses appear at pin DATA. The edge-to-edge time period t
ee
of the majority of these
noise pulses is equal to or slightly higher than T
DATA_min
.
Switching the Receiver Back
to Sleep Mode The receiver can be set back to polling mode via pin DATA or via pin ENABLE.
When using pin DATA, this pin must be pulled to low for the period t1 by the connected
microcontroller. Figure 17 illustrates the timing of the OFF command (see also Figure 21
on page 21). The minimum value of t1 depends on the BR_Range. The maximum value
for t1 is not limited but it is recommended not to exceed the specified value to prevent
erasing the reset marker. This item is explained in more detail in the section “Configura-
tion of the Receiver” on page 17. Setting the receiver to sleep mode via DATA is
achieved by programming bit 1 of the OPMODE register to 1. Only one sync pulse (t3) is
issued.
The duration of the OFF command is determined by the sum of t1, t2 and t10. After the
OFF command, the sleep time T
Sleep
elapses. Note that the capacitive load at pin DATA
is limited. The resulting time constant
τ
together with an optional external pull-up resis-
tor may not be exceeded to ensure proper operation.
Clock Bitcheck
counter
DATA
T
XClk
Dem_out
t
ee
DATA
tmin1 Lim_min ≤ CV_Lim < Lim_max
Dem_out
t
ee
tmin2
t
ee
CV_Lim < Lim_min or CV_Lim ≥ Lim_max
Bit check
Enable IC
DATA
Sleep mode Receiving mode
tmin2
Bit check mode
t
DATA_L_max
Dem_out