34
Analog Front End IC TMS37122 - Reference Guide
August ’01
Figure 20: Default Memory Content
The default PPM Threshold is configured for a medium data rate of 2kBit/s, realized for ex-
ample with a low bit period of tbitL=400 and a high bit period of tbitH=600µs (see Figure
12). It is assumed that toff is as short as possible (toff<=100µs), but still achieving 50% mod-
ulation (m=33%) under all conditions. Under this assumptions CLKA is available continu-
ously or interrupted only shortly during toff. If this cannot be achieved due to lower quality
factors and thereore stronger damping, or if higher data rates are demanded, PPM Threshold
must be adapted.
0
1
2
3
NIBBLE
ROW
1
2
Bit 0
Bit 3
Bit 3
Bit 0
VWAKE B/ 1
VWAKE A/ 1
Bit 3
Bit 0
VWAKE B/ 2/3
PPM THRESHOLD
Bit 0
Bit 3
Bit 0
4
0
NO
WAKE
PASSIVE ENTRY WAKE PATTERN
C_TELEGR
PASSIVE START WAKE PATTERN
C_WAIT
Bit 15
Bit 0
Bit 3
Bit 3
Bit 0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
NO
WDE2
NO
WDE3
NO
CLKA
1
3DMEMD4.DRW