ON Semiconductor NCN49597, Руководство пользователя, Страница: 2 / 28

NCN49597
http://onsemi.com
2
APPLICATION
Application Example
PC201 11120 .1
TX_OUT
NCN49597
TX_ENB
ZC_IN
REF_OUT
RX_IN
RX_OUT
XT
AL
_I
N
XT
AL
_
O
U
T
Appli
&
Metering
m C
TXD
RXD
BR0
BR1
RESB
VS
S
A
VS
S
T_REQ
VD
D
V
DDA
3V3_A 3V3_D
1:2
C
1
R
1
C
2
R
2
C
DREF
C
16
C
17
3V3_A
D
5
D
1
D
2
D
3
D
4
R
12
C
11
C
12
R
14
C
15
C
14
Y
1
NCS5650
En
ab
le
C
3
C
4
C
6
C
7
R
6
R
5
R
4
R
7
R
9
R
10
2
Vcom
+B
− B
+A
− A
OutA
OutB 8
9
13
12 5
4
3
1
6
7
VCC
10 11
VEE
Vuc
19
15 14 20
GNDuC
Rlim
Vwarn
3V3_D 12V
R
11
C
5
C
10
C
9
12V
R
3
MAINS
Tr
C
8
C
13
U
1
U
2
3V3_D
VDD1V8
R
8
SEN
EXT_CLK_E
Figure 1. Typical Application for the NCN49597S − FSK Modem
Figure 1 shows an S − FSK PLC modem build around
NCN49597. For synchronization the line frequency is
coupled in via a 1 M
W resistor. The Schottky diode pair D
5
clamps the voltage within the input range of the zero cross
detector. In the receive path a 2
nd
order high pass filter
blocks the mains frequency. The corner point defined by C
1
,
C
2
, R
1
and R
2
is designed at 10 kHz. In the transmit path a
3
th
order low pass filter build around the NCS5650 power
operational amplifier suppresses the 2
nd
and 3
rd
harmonics
to be in line with the CENELEC EN 50065 − 1 specification.
The filter components are tuned for a space and mark
frequency of 63.3 and 74 kHz respectively. The output of the
amplifier is coupled via a DC blocking capacitor C
10
to a 2:1
pulse transformer Tr. The secondary of this transformer is
coupled to the mains via a high voltage capacitor C
11
. High
energetic transients from the mains are clamped by the
protection diode combination D
3
, D
4
together with D
1
, D
2
.
Because the mains is not galvanic isolated care needs to be
taken when interfacing to a microcontroller or a PC!
Table 1. EXTERNAL COMPONENTS LIST AND DESCRIPTION
Component Function − Remark Typ Value Tolerance Unit
C
1
, C
2
High pass receive filter 1.5 ± 10% nF
C
5
, C
DREF
V
REF_OUT
; V
REF_OUT
decoupling cap − ceramic 1 − 20 +80%
m
F
C
7
, C
9
, C
16
, C
17
Decoupling block capacitor 100 − 20 +80% nF
C
3
TX_OUT coupling capacitor 470 ± 20% nF
C
4
Low pass transmit filter 470
±
10% pF
C
6
Low pass transmit filter 68
±
10% pF
C
8
Low pass transmit filter 3 ± 10% pF
C
10
TX coupling cap; 1 A rms ripple @ 70 kHz 10
±
20%
m F