Datasheet

PCF2127AT All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 6 — 11 July 2013 56 of 86
NXP Semiconductors
PCF2127AT
Integrated RTC, TCXO and quartz crystal
9. Interfaces
The PCF2127AT has an I
2
C-bus or SPI-bus interface using the same pins. The selection
is done by using the interface selection pin IFS (see Table 57
).
Table 57. Interface selection input pin IFS
Pin Connection Bus interface Reference
IFS V
SS
SPI-bus Section 9.1
BBS I
2
C-bus Section 9.2
To select the SPI-bus interface, pin IFS has to be
connected to pin V
SS
.
To select the I
2
C-bus interface, pin IFS has to be
connected to pin BBS.
a. SPI-bus interface selection b. I
2
C-bus interface selection
Fig 33. Interface selection
001aaj679
1
V
DD
BBS
SCL
CE
20
PCF2127AT
2
SDI
19
3
SDO
18
4
SDA/CE
17
5
IFS
16
615
714
8
V
SS
13
912
10 11
SDO
SDI
SCL
V
DD
V
SS
001aaj680
1
V
DD
BBS
SCL
20
PCF2127AT
2
SDI
19
3
SDO
18
4
SDA/CE
17
5
IFS
16
615
714
8
V
SS
V
SS
13
SDA
SCL
R
PU
R
PU
V
DD
912
10 11