U3745BM Datasheet, PDF (20/29 Pages) ATMEL Corporation – UHF ASK RECEIVER IC

Table 9. Effect of the Configuration Word Lim_min
Lim_min
Lim_min < 10 is not applicable
0
0
1
0
1
0
0
0
1
0
1
1
0
0
1
1
0
0
0
0
1
1
0
1
0
0
1
1
1
0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1
1
1
1
0
1
1
1
1
1
1
0
1
1
1
1
1
1
Lower Limit Value for Bit Check
(T_{Lim_min} = Lim_min ´ XLim ´ T_Clk)
10
11
12
13
14 (Default)
(USA: T_{Lim_min} = 228 µs, Europe: T_{Lim_min} = 232 µs)
61
62
63
Table 10. Effect of the Configuration Word Lim_max
Lim_max
Lim_max < 12 is not applicable
0
0
1
1
0
0
0
0
1
1
0
1
0
0
1
1
1
0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
0
1
1
0
0
0
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
1
1
1
1
0
1
1
1
1
1
1
0
1
1
1
1
1
1
Upper Limit Value for Bit Check
(T_{Lim_max} = (Lim_max - 1) ´ XLim ´ T_Clk)
12
13
14
24 (Default)
(USA: T_{Lim_max} = 375 µs, Europe: T_{Lim_max} = 381 µs)
61
62
63
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.
20 U3745BM
4663A–RKE–06/03