DS1554-100 DALLAS [Dallas Semiconductor], DS1554-100 Datasheet - Page 2

• Manufacturer Part Number: DS1554-100
• Description: 256K NV Y2KC Timekeeping RAM
• Manufacturer: DALLAS [Dallas Semiconductor]

ORDERING INFORMATION
DS1554P-XXX
*DS1554WP-XXX
*DS9034PCX (PowerCap) Required:
PIN DESCRIPTION
A0-A14
DQ0-DQ7
V
GND
NC
X1, X2
V
DESCRIPTION
The DS1554 is a full function, year 2000-compliant (Y2KC), real-time clock/calendar (RTC) with a RTC
alarm, watchdog timer, power-on reset, battery monitor, and 32k x 8 non-volatile static RAM. User
access to all registers within the DS1554 is accomplished with a bytewide interface as shown in Figure 1.
The RTC Registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour
BCD format. Corrections for day of month and leap year are made automatically.
The RTC Registers are double-buffered into an internal and external set. The user has direct access to the
external set. Clock/calendar updates to the external set of registers can be disabled and enabled to allow
the user to access static data. Assuming the internal oscillator is turned on, the internal set of registers are
continuously updated; this occurs regardless of external registers settings to guarantee that accurate RTC
information is always maintained.
IRQ
RST
CE
OE
WE
CC
BAT
\FT
blank 32-pin DIP Module
P
blank 32-pin DIP Module
P
must be ordered seperately
(5-Volt)
-70
-100
(3.3 Volt)
-120
-150
34-pin PowerCap Module
board*
- Address Input
- Data Input/Outputs
- Chip Enable
- Output Enable
- Write Enable
- Power Supply Input
- Ground
- No Connection
- Crystal Connection
- Battery Connection
board*
- Interrupt, Frequency Test Output
- Power-On Reset Output
34-pin PowerCap Module
(Open Drain)
(Open Drain)
70 ns access
100 ns access
120 ns access
150 ns access
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DS1554