CLRC663 Datasheet, PDF (39/132 Pages) NXP Semiconductors – Contactless reader IC

NXP Semiconductors
CLRC663
Contactless reader IC
Table 28. Setting residual carrier …continuedand modulation index by
set_residual_carrier (decimal) residual carrier [%]
modulation index [%]
23
65
21.2
24
60
25.0
25
55
29.0
26
50
33.3
27
45
37.9
28
40
42.9
29
35
48.1
30
30
53.8
31
25
60.0
Note: When VDD(TVDD) < 5 V it is not recommended to use a residual carrier < 50 %
8.6.2.1 Overshoot protection
The CLRC663 provides an overshoot protection for 100% ASK to avoid overshoots during
a PCD communication. Therefore two timers overshoot_t1 and overshoot_t2 can be used.
During the timer overshoot_t1 runs an amplitude defined by set_cw_amplitude bits is
provided to the output driver. Followed by an amplitude denoted by set_residual_carrier
bits with the duration of overshoot_t2.
7.0
(V)
5.0
3.0
1.0
-1.0
2.50
3.03
3.56
4.10
time (μs)
001aan356
Fig 26. Example 1: overshoot_t1 = 2d; overhoot_t2 = 5d.
CLRC663
Product data sheet
COMPANY PUBLIC
All information provided in this document is subject to legal disclaimers.
Rev. 3.3 — 3 April 2012
171133
© NXP B.V. 2012. All rights reserved.
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