Moteur de recherche de fiches techniques de composants électroniques |
|
STK1744-D45 Fiches technique(PDF) 7 Page - List of Unclassifed Manufacturers |
|
STK1744-D45 Fiches technique(HTML) 7 Page - List of Unclassifed Manufacturers |
7 / 12 page 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 X 10 Hours Hours Hours: 00 - 23 7FFC 1 FT X X X Days Days: 01 - 07 7FFD X X 10 Dates Dates Dates: 01 - 31 7FFE X X 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 |
Numéro de pièce similaire - STK1744-D45 |
|
Description similaire - STK1744-D45 |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |