STK1744-D45 datasheet(7/12 Pages) ETC

Numer części	STK1744-D45

Szczegółowy opis	32K x 8 AutoStore nvSRAM with Real-Time Clock

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STK1744

January 2003

7

Document Control # ML0020 rev 0.0

The STK1744 is a 32K x 8 nonvolatile static RAM

with a full-function real-time clock (RTC). Nonvolatile

data is preserved in integral QuantumTrap

 Nonvol-

atile Elements and is not subject to battery failure or

capacitor discharge. The real-time clock registers

reside in the eight uppermost RAM locations, and

contain century, year, month, date, day, hour, minute

and second data in 24-hour BCD format. Corrections

for the day of the month and leap years are made

automatically. This nonvolatile time-keeping RAM is

functionally similar to any JEDEC standard 32K x 8

SRAM

.

The RTC registers are double-buffered to avoid

access of incorrect data that could otherwise occur

during clock update cycles. The double-buffered

system prevents time loss by maintaining internal

clock operation while time register data is accessed.

The STK1744 contains integral power-fail circuitry

that deselects the device when V

CC drops below

V

SWITCH.

The STK1744 is a pin-compatible replacement for

the ST Microelectronics M48T35 and the Dallas

Semiconductor DS1744, but without the limitations

of an embedded lithium battery. The Simtek module

uses a double-layer high-value capacitor to maintain

RTC

operation on every power down for at least 30

days. The part can be soldered directly onto printed

circuit boards and handled without concern for dam-

aging or discharging internal batteries. Unlike some

other RTCs, the STK1744 is Year 2000-compliant.

NOISE CONSIDERATIONS

Note that the STK1744 is a high-speed memory and

so must have a high-frequency bypass capacitor of

approximately 0.1

µF connected between V

CC and

V

SS, using leads and traces that are as short as pos-

sible. As with all high-speed CMOS ICs, normal care-

ful routing of power, ground and signals will help

prevent noise problems.

SRAM AND RTC READ

The STK1744 performs a READ cycle whenever E

and G are low and W is high. The address specified

on pins A

0-14 determines which of the 32,760 data

bytes or 8 RTC registers will be accessed. When the

READ

is initiated by an address transition, the out-

puts will be valid after a delay of t

AVQV (READ cycle

#1). If the READ is initiated by E or G, the outputs will

be valid at t

ELQV or at tGLQV, whichever is later (READ

cycle #2). The data outputs will repeatedly respond to

address changes within the t

AVQV access time without

the need for transitions on any control input pins, and

will remain valid until another address change or until

E or G is brought high or W is brought low.

Note that the eight most significant bytes of the

address space are reserved for accessing the RTC

registers, as shown in the RTC Register Map.

While the double-buffered RTC register structure

reduces the chance of reading incorrect data from the

clock, the user should halt internal updates to the

DEVICE OPERATION

RTC REGISTER MAP

ADDRESS

(HEXADECIMAL)

BCD DATA

FUNCTION/RANGE

D7

D6

D5

D4

D3

D2

D1

D0

7FF8

W

R

10 Centuries

Centuries

Centuries: 00 - 39, Control

7FF9

X

10 Seconds

Seconds

Seconds: 00 - 59

7FFA

X

10 Minutes

Minutes

Minutes:

00 - 59

7FFB

X

10 Hours

Hours

Hours:

00 - 23

7FFC

1

FT

X

Days

Days:

01 - 07

7FFD

X

10 Dates

Dates

Dates:

01 - 31

7FFE

X

10 Mos.

Months

Months:

01 - 12

7FFF

10 Years

Years

Years:

00 - 99

Key:

R = Read Bit

W= Write Bit

1 = Battery Flag high (there is no battery to fail)

FT = Frequency test bit

X = Don’t Care

Podobny numer części - STK1744-D45

Producent	Numer części	Arkusz danych	Szczegółowy opis
List of Unclassifed Man...	STK1743	253Kb / 10P	NV TIME 8K X 8 AUTOSTORE NVSRAM WITH REAL - TIME CLOCK
	STK1743-D25	253Kb / 10P	NV TIME 8K X 8 AUTOSTORE NVSRAM WITH REAL - TIME CLOCK
	STK1743-D25I	253Kb / 10P	NV TIME 8K X 8 AUTOSTORE NVSRAM WITH REAL - TIME CLOCK
	STK1743-D35	253Kb / 10P	NV TIME 8K X 8 AUTOSTORE NVSRAM WITH REAL - TIME CLOCK
	STK1743-D35I	253Kb / 10P	NV TIME 8K X 8 AUTOSTORE NVSRAM WITH REAL - TIME CLOCK

More results

Podobny opis - STK1744-D45

Producent	Numer części	Arkusz danych	Szczegółowy opis
Cypress Semiconductor	STK17T88	603Kb / 22P	32K x 8 AutoStore nvSRAM with Real Time Clock
Simtek Corporation	STK17T88	535Kb / 29P	32K x 8 AutoStore nvSRAM with Real-Time Clock
Cypress Semiconductor	STK17TA8	787Kb / 23P	128k X 8 AutoStore nvSRAM with Real Time Clock
List of Unclassifed Man...	STK17T88	284Kb / 25P	nvTime Event Data Recorder 32K x 8 AutoStore nvSRAM With Real-Time Clock
List of Unclassifed Man...	STK1743	253Kb / 10P	NV TIME 8K X 8 AUTOSTORE NVSRAM WITH REAL - TIME CLOCK
Simtek Corporation	STK17TA8	685Kb / 28P	128Kx8 Autostore nvSRAM With Real-Time Clock
Cypress Semiconductor	CY14B256KA	755Kb / 26P	256 Kbit (32K x 8) nvSRAM with Real Time Clock
Simtek Corporation	STK17TA8	647Kb / 29P	128Kx8 Autostore nvSRAM With Real-Time Clock
Cypress Semiconductor	CY14B256K	1Mb / 23P	256-Kbit (32K x 8) nvSRAM with Real-Time-Clock
Cypress Semiconductor	CY14B256K	796Kb / 28P	256 Kbit (32K x 8) nvSRAM with Real Time Clock

More results

STK1744-D45 Arkusz danych(PDF) 7 Page - List of Unclassifed Manufacturers

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