ez80f91 ZiLOG Semiconductor, ez80f91 Datasheet - Page 167

• Manufacturer Part Number: ez80f91
• Description: Ez80 Acclaimplus!? Connectivity Assp Ez80f91 Assp
• Manufacturer: ZiLOG Semiconductor

Real-Time Clock
PS027001-0707
System Clock
Note:
Real-Time Clock Overview
The Real-Time Clock (RTC) maintains time by keeping count of seconds, minutes, hours,
day-of-the-week, day-of-the-month, year, and century. The current time is kept in 24-hour
format. The format for all count and alarm registers is selectable between binary and
binary-coded-decimal (BCD) operations. The calendar operation maintains the correct
day-of-the-month and automatically compensates for leap year. A simplified block
diagram of the RTC and the associated on-chip, low-power, 32 kHz oscillator is illustrated
in
demonstrated in
For users NOT using the RTC the following RTC signal pins must be connected as follows
to avoid a 10 uA leakage within the RTC circuit block. RTC_Xin (pin 61) must be left
floating or connected to ground.
Figure 35. Real-Time Clock and 32 kHz Oscillator Block Diagram
Figure
IRQ
ADDR[15:0]
DATA[7:0]
Real-Time Clock
35. Connections to an external battery supply and 32 kHz crystal network is also
V
RTC Clock
DD
Figure
(RTC_CTRL[4])
CLK_SEL
35.
Enable
V
DD
Low-Power
32 KHz Oscillator
RTC_X
RTC_X
RTC_V
DD
OUT
IN
32 KHz
Crystal
R1
Product Specification
Battery
eZ80F91 ASSP
Real-Time Clock
C
C
159