DS1643-100 Maxim Integrated Products, DS1643-100 Datasheet - Page 4

• Manufacturer Part Number: DS1643-100
• Description: IC RAM TIMEKEEP NV 100NS 28-EDIP
• Manufacturer: Maxim Integrated Products
• Type: Clock/Calendar/NVSRAMr

Specifications of DS1643-100

• Memory Size: 64K (8K x 8)
• Time Format: HH:MM:SS (24 hr)
• Date Format: YY-MM-DD-dd
• Interface: Parallel
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 28-DIP Module (600 mil), 28-EDIP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: DS1643100

Figure 1. Block Diagram
Table 1. Truth Table
SETTING THE CLOCK
The 8-bit of the control register is the write bit. Setting the write bit to a 1, like the read bit, halts updates
to the DS1643 registers. The user can then load them with the correct day, date and time data in 24 hour
BCD format. Resetting the write bit to a 0 then transfers those values to the actual clock counters and
allows normal operation to resume.
STOPPING AND STARTING THE CLOCK OSCILLATOR
The clock oscillator may be stopped at any time. To increase the shelf life, the oscillator can be turned off
to minimize current drain from the battery. The
a 1 stops the oscillator.
FREQUENCY TEST BIT
Bit 6 of the day byte is the frequency test bit. When the frequency test bit is set to logic 1 and the
oscillator is running, the LSB of the seconds register will toggle at 512Hz. When the seconds register is
being read, the DQ0 line will toggle at the 512Hz frequency as long as conditions for access remain valid
(i.e.,
5V 10%
<4.5V >
<V
V
V
CE
BAT
CC
BAT
low,
OE
V
V
V
V
CE
low, CE2 high, and address for seconds register remain valid and stable).
X
X
X
IH
IL
IL
IL
CE2
V
V
V
V
X
X
X
IL
IH
IH
IH
V
V
OE
X
X
X
X
X
IH
IL
WE
V
V
V
DS1643P
DS1643/
X
X
X
X
IH
IH
IL
OSC
4 of 17
bit is the MSB for the seconds registers. Setting it to
Deselect
Deselect
Deselect
Deselect
MODE
Write
Read
Read
Data Out
Data In
High-Z
High-Z
High-Z
High Z
High Z
DQ
Data Retention Mode
CMOS Standby
DS1643/DS1643P
POWER
Standby
Standby
Active
Active
Active