Specifications

CY14B108K
CY14B108M
Document Number: 001-47378 Rev. *K Page 13 of 36
RTC External Components
The RTC requires connecting an external 32.768 kHz crystal and C
1
, C
2
load capacitance as shown in the Figure 5. The figure shows
the recommnded RTC external component values. The load capacitances C
1
and C
2
are inclusive of parasitic of the printed circuit
board (PCB). The PCB parasitic includes the capacitance due to land pattern of crystal pads/pins, X
in
/X
out
pads and copper traces
connecting crystal and device pins.
Figure 4. Interrupt Block Diagram
WDF - Watchdog Timer Flag
WIE - Watchdog Interrupt
PF - Power Fail Flag
PFE - Power Fail Enable
AF - Alarm Flag
AIE - Alarm Interrupt Enable
P/L - Pulse Level
H/L - High/Low
Enable
Watchdog
Timer
Power
Monitor
Clock
Alarm
VINT
WDF
WIE
PF
PFE
AF
AIE
P/L
Pin
Driver
H/L
INT
V
CC
V
SS
Figure 5. RTC Recommended Component Configuration
[12]
Recommended Values
Y
1
= 32.768 KHz (12.5 pF)
C
1
= 12 pF
C
2
= 69 pF
Note: The recommended values for C1 and C2 include
board trace capacitance.
X
out
X
in
Y1
C2
C1
Note
12. For nonvolatile static random access memory (nvSRAM) real time clock (RTC) design guidelines and best practices, see application note AN61546.