Rainbow Electronics U3745BM - Manual (Page 20)

20
U3745BM
4663A–RKE–06/03
Table 9. Effect of the Configuration Word Lim_min
Table 10. Effect of the Configuration Word Lim_max
Conservation of the Register
Information The U3745BM has an integrated power-on reset and brown-out detection circuitry to
provide a mechanism to preserve the RAM register information.
According to Figure 18, a power-on reset (POR) is generated if the supply voltage V
S
drops below the threshold voltage V
ThReset
. The default parameters are programmed into
the configuration registers in that condition. Once V
S
exceeds V
ThReset
, the POR is can-
celed after the minimum reset period t
Rst
. A POR is also generated when the supply
voltage of the receiver is turned on.
To indicate that condition, the receiver displays a reset marker (RM) at pin DATA after a
reset. The RM is represented by the fixed frequency f
RM
at a 50% duty cycle. RM can be
canceled via an ‘L’ pulse t1 at pin DATA. The RM implies the following characteristics:
• f
RM
is lower than the lowest feasible frequency of a data signal. By this means, RM
cannot be misinterpreted by the connected microcontroller.
Lim_min Lower Limit Value for Bit Check
Lim_min < 10 is not applicable (T
Lim_min
= Lim_min ´ XLim ´ T
Clk
)
0 0 1 0 1 0 10
0 0 1 0 1 1 11
0 0 1 1 0 0 12
0 0 1 1 0 1 13
0 0 1 1 1 0 14 (Default)
(USA: T
Lim_min
= 228 µs, Europe: T
Lim_min
= 232 µs)
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1 1 1 1 0 1 61
1 1 1 1 1 0 62
1 1 1 1 1 1 63
Lim_max Upper Limit Value for Bit Check
Lim_max < 12 is not applicable (T
Lim_max
= (Lim_max - 1) ´ XLim ´ T
Clk
)
0 0 1 1 0 0 12
0 0 1 1 0 1 13
0 0 1 1 1 0 14
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0 1 1 0 0 0 24 (Default)
(USA: T
Lim_max
= 375 µs, Europe: T
Lim_max
= 381 µs)
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1 1 1 1 0 1 61
1 1 1 1 1 0 62
1 1 1 1 1 1 63