1
FN1547.9
CDP68HC68T1
CMOS Serial Real-Time Clock With RAM
and Power Sense/Control
The CDP68HC68T1 Real-Time Clock provides a
time/calendar function, a 32 byte static RAM, and a 3 wire
Serial Peripheral Interface (SPI Bus). The primary function of
the clock is to divide down a frequency input that can be
supplied by the on-board oscillator in conjunction with an
external crystal or by an external clock source. The internal
oscillator can operate with a 32kHz, 1MHz, 2MHz, or 4MHz
crystal. An external clock source with a 32kHz, 1MHz, 2MHz,
4MHz, 50Hz or 60Hz frequency can be used to drive the
CDP68HC68T1. The time registers hold seconds, minutes,
and hours, while the calendar registers hold day-of-week,
date, month, and year information. The data is stored in BCD
format. In addition, 12 or 24 hour operation can be selected.
In 12 hour mode, an AM/PM indicator is provided. The T1
has a programmable output which can provide one of seven
outputs for use elsewhere in the system.
Computer handshaking is controlled with a “wired-OR” interrupt
output. The interrupt can be programmed to provide a signal as
the result of:
1. An alarm programmed to occur at a predetermined
combination of seconds, minutes, and hours.
2. One of 15 periodic interrupts ranging from sub-second to
once per day frequency.
3. A power fail detect. The PSE output and the V
SYS
input are
used for external power control. The CPUR output is
available to reset the processor under power-down
conditions. CPUR
is enabled under software control and
can also be activated via the CDP68HC68T1’s watchdog. If
enabled, the watchdog requires a periodic toggle of the CE
pin without a serial transfer.
Features
• SPI (Serial Peripheral Interface)
• Full Clock Features
- Seconds, Minutes, Hours (12/24, AM/PM), Day of
Week, Date, Month, Year (0 to 99), Automatic Leap Year
•32 Wordx8-Bit RAM
• Seconds, Minutes, Hours Alarm
• Automatic Power Loss Detection
• Low Minimum Standby (Timekeeping) Voltage . . . . . 2.2V
• Selectable Crystal or 50/60Hz Line Input
• Buffered Clock Output
• Battery Input Pin that Powers Oscillator and also
Connects to V
DD
Pin When Power Fails
• Three Independent Interrupt Modes
-Alarm
- Periodic
- Power-Down Sense
• Pb-Free Available (RoHS Compliant)
Pinouts
CDP68HC68T1
(16 LD PDIP, SOIC)
TOP VIEW
CDP68HC68T1
(20 LD SOIC)
TOP VIEW
9
10
11
12
13
14
16
15
8
7
6
5
4
3
2
1
CLKOUT
CPUR
INT
SCK
MOSI
MISO
V
SS
CE
V
DD
XTAL IN
V
BATT
V
SYS
XTAL OUT
LINE
POR
PSE
11
12
13
14
15
16
17
18
20
19
10
9
8
7
6
5
4
3
2
1
CLK OUT
CPUR
INT
NC
SCK
MOSI
CE
MISO
V
SS
PSE
VDD
XTAL IN
NC
V
BATT
XTAL OUT
V
SYS
NC
NC
LINE
POR
Data Sheet Decemember 8, 2015
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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