 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| DS1284 Watchdog Timekeeper Chip www.dalsemi.com FEATURES Keeps track of hundredths of seconds, seconds, minutes, hours, days, date of the month, months, and years; valid leap year compensation up to 2100 Watchdog timer restarts an out-of-control processor Alarm function schedules real-time related activities Programmable interrupts and square wave outputs maintain 28-pin JEDEC footprint All registers are individually addressable via the address and data bus Accuracy is better than 2 minute/month at 25C 50 bytes of user NV RAM Optional 28-pin PLCC surface mount package Low-power CMOS circuitry is maintained on less than 0.5 A when power is supplied from battery input Optional industrial temperature range available on 28-pin PLCC (-40C to +85C) PIN ASSIGNMENT INTA X1 X2 NC A5 A4 A3 A2 A1 A0 DQ0 DQ1 DQ2 GND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 NC X2 X1 INTA VCC WE INTB(INTB) 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 3 2 1 28 27 26 25 24 23 22 21 20 19 VCC WE INTB(INTB) VBAT RCLR SQW A5 OE A4 A3 GND A2 CE A1 DQ7 A0 DQ6 DQ0 DQ5 DQ4 DQ3 VBAT RCLR SQW OE GND CE DQ7 DS1284 28-Pin DIP (600-mil) DS1284 28-Pin PLCC PIN DESCRIPTION - Interrupt Output A (open drain) INTB (INTB) - Interrupt Output B (open drain) A0-A5 - Address Inputs DQ0-DQ7 - Data Input/Output - Chip Enable CE - Output Enable OE - Write Enable WE VCC - +5 Volts GND - Ground NC - No Connection SQW - Square Wave Output X1,X2 - 32.768 kHz Crystal Connections VBAT - +3 Volt Battery Input - RAM Clear RCLR INTA DESCRIPTION The DS1284 Watchdog Timekeeper Chip is a self-contained real-time clock, alarm, watchdog timer, and interval timer in a 28-pin JEDEC DIP package or a 28-pin PLCC surface mount package. An external crystal and battery are the only components required to maintain time-of-day and memory status in the absence of power. For a complete description of operating conditions, electrical characteristics, bus timing, and pin descriptions other than X1, X2, VBAT, and RCLR , see the DS1286 Watchdog Timekeeper data sheet. 1 of 3 DQ1 DQ2 GND DQ3 DQ4 DQ5 DQ6 072799 DS1284 PIN DESCRIPTION X1, X2 - Connections for a standard 32.768 kHz quartz crystal. The internal oscillator circuitry is designed for operation with a crystal having a specified load capacitance (CL) of 6 pF. The crystal is connected directly to the X1 and X2 pins. There is no need for external capacitors or resistors. For more information on crystal selection and crystal layout considerations, please consult Application Note 58, "Crystal Considerations with Dallas Real Time Clocks." VBAT - Battery input for any standard 3-volt lithium cell or other energy source. Battery voltage must be held between 2.4 and 3.7 volts for proper operation. The nominal write-protect trip point voltage at which access to registers containing time, watchdog, alarm, and RAM information is denied is set by internal circuitry as 1.26 x VBAT. A maximum load of 0.5 A at 25C in the absence of power should be used to size the external energy source. The battery should be connected directly to the VBAT pin. A diode must not be placed in series with the battery to the VBAT pin. Furthermore, a diode is not necessary because reverse charging current protection circuitry is provided internal to the device and has passed the requirements of Underwriters Laboratories for UL listing. An optional ground pin is provided for connection to battery negative. This pin should be grounded but can be left floating. RCLR - The RCLR pin is used to clear (set to logic 1) all 50 bytes of user NV RAM but does not affect the registers involved with time, alarm, and watchdog functions. In order to clear the RAM, RCLR must be forced to an input logic 0 (-0. 3 to +0.8 volts) during battery back-up mode when VCC is not applied. The RCLR function is designed to be used via human interface (shorting to ground or by switch) and not be driven with external buffers. This pin is internally pulled up and should be left floating when not in use. DS1284Q 28-PIN PLCC WATCHDOG TIMEKEEPER PKG DIM A IN. MM B IN. MM D IN. MM D2 IN. MM E IN. MM E2 IN. MM F IN. MM H IN. MM 28-PIN MIN MAX 0.300 BSC 7.62 0.442 0.462 17.68 11.73 0.480 0.500 12.2 12.7 0.390 0.430 9.91 10.92 0.090 0.120 2.29 3.05 0.390 0.430 9.91 10.92 0.015 0.020 0.38 0.518 0.100 0.020 2.54 0.518 2 of 3 DS1284 DS1284 28-PIN DIP WATCHDOG TIMEKEEPER PKG DIM A IN. MM B IN. MM C IN. MM D IN. MM E IN. MM F IN. MM G IN. MM H IN. MM J IN. MM K IN. MM 28-PIN MIN MAX 1.445 0.530 0.140 0.600 0.015 0.120 0.090 0.625 0.008 0.015 1.470 0.550 0.160 0.625 0.040 0.145 0.110 0.675 0.012 0.022 3 of 3 |
Price & Availability of DS1284
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |