CMX7861 FirmCODEC® Programmable Baseband Interface
CMX7861
4
PCB Layout Guidelines and Power Supply Decoupling
C26 C27
+
Digital Ground Plane
DVSS
C-BUS
Active low reset from
supervisory IC or RC circuit
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
GPIOB
DVSS5
DVSS4
NC
1
2
48
47
46
45
44
43
BOOTEN1
BOOTEN2
DVSS1
DVDD
DVDD
3
DVSS
DVDD2
DVCORE1
DVSS3
4
DVDD1
5
C28
C22
+
C20 C21
SSOUT2
RESETN
GPIOC
6
CMX7861Q1
AUXDAC4
AUXDAC3
AUXDAC2
AUXDAC1
AVSS3
7
42
41
40
39
38
37
36
35
34
33
DVSS
8
GPIOD
9
DVSS
DVSS2
10
OUTPUT3
AVDD1
AVDD
11
12
13
14
15
AVDD3
OP4VSS
AUXADC4
AUXADC3
AUXADC2
AUXADC1
C23 C24
+
C25
OUTPUT4P
OUTPUT4N
OP4VDD
C29
C30
AVSS
+
AVSS
16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
AVDD
C31
Analogue Ground Plane
AVSS
C20 10µF
C26 22µF
C27 10nF
C28 10nF
C29 10µF
C30 10nF
C31 100nF
C21 10nF
C22 10nF
C23 10µF
C24 10nF
C25 10nF
Figure 2 CMX7861 Power Supply and De-coupling
Notes:
To achieve good noise performance, AVDD and VBIAS decoupling and protection of the receive path from
extraneous in-band signals is very important. It is recommended that the printed circuit board is laid out
with a ground plane in the CMX7861 analogue area to provide a low impedance connection between the
AVSS pins and the AVDD and VBIAS decoupling capacitors.
2012 CML Microsystems Plc
Page 10
D/7861_FI-1.x/2
CMLMICRO [ CML MICROCIRCUITS ]
