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DS17485 Dataheets PDF



Part Number DS17485
Manufacturers Dallas
Logo Dallas
Description (DS17486 / DS17487) 3V/5V Real-Time Clock
Datasheet DS17485 DatasheetDS17485 Datasheet (PDF)

DS17485/DS17487 3V/5V Real-Time Clock www.maxim-ic.com FEATURES Incorporates industry standard DS1287 PC clock plus enhanced features: § Y2K compliant § +3V or +5V operation § SMI recovery stack § 64-bit silicon serial number § Power-control circuitry supports system power-on from date/time alarm or key closure § 32kHz output on power-up § Crystal select bit allows RTC to operate with 6pF or 12.5pF crystal § 114 bytes user NV RAM § Auxiliary battery input § 4kB additional NV RAM § RAM clear inp.

  DS17485   DS17485



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DS17485/DS17487 3V/5V Real-Time Clock www.maxim-ic.com FEATURES Incorporates industry standard DS1287 PC clock plus enhanced features: § Y2K compliant § +3V or +5V operation § SMI recovery stack § 64-bit silicon serial number § Power-control circuitry supports system power-on from date/time alarm or key closure § 32kHz output on power-up § Crystal select bit allows RTC to operate with 6pF or 12.5pF crystal § 114 bytes user NV RAM § Auxiliary battery input § 4kB additional NV RAM § RAM clear input § Century register § Date alarm register § Compatible with existing BIOS for original DS1287 functions § Available as chip (DS17485) or standalone module with embedded battery and crystal (DS17487) § Timekeeping algorithm includes leap-year compensation valid up to 2100 § Underwriters Laboratory (UL) recognized PIN ASSIGNMENT PWR X1 X2 AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 GND 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 VCC SQW VBAUX RCLR VBAT IRQ KS RD GND WR ALE CS DS17485 24-Pin DIP DS17485S 24-Pin SO PWR NC NC AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 GND 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 VCC SQW VBAUX RCLR NC IRQ KS RD NC WR ALE CS DS17487 24-Pin Encapsulated Package TYPICAL OPERATING CIRCUIT IRQ VBAT RCLR VBAUX SQW VCC VCC PWR X1 X2 NC ADO AD1 AD2 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 KS RD GND WR ALE CS GND GND AD7 AD6 NC AD5 AD4 AD3 DS17485E 28-Pin TSOP 1 of 38 050802 DS17485/DS17487 ORDERING INFORMATION PART # DESCRIPTION DS17485XX-X RTC Chip 3 5 +3V operating range +5V operating range blank commercial temp range N industrial temp range blank 24-pin DIP E 28- pin TSOP S 24- pin SO DS17487X-X RTC Module; 24-pin DIP 3 5 +3V operating rang +5V operating range blank commercial temp range N industrial PIN DESCRIPTION RCLR AD0–AD7 PWR KS CS ALE WR RD IRQ SQW VCC GND VBAT VBAUX NC X1 X2 Crystal Input Crystal Output RAM Clear Input Multiplexed Address/Data Bus Power-On Interrupt Output (Open Drain) Kickstart Input RTC Chip-Select Input RTC Address Strobe RTC Write Data Strobe RTC Read Data Strobe Interrupt Request Output (Open Drain) Square-Wave Output +3V or +5V Main Supply Ground Battery + Supply Auxiliary Battery Supply No Connect DESCRIPTION The DS17485/DS17487 are real-time clocks (RTC) designed as successors to the industry standard DS1285, DS1385, DS1485, DS1585, and DS1685 PC real-time clocks. These devices provide the industry standard DS1285 clock function with either +3V or +5V operation. The DS17485 also incorporates a number of enhanced features including a silicon serial number, power-on/off control circuitry, 114 bytes of user NV SRAM plus 4kB of additional NV RAM, and 32.768kHz output for sustaining power management activities. 2 of 38 DS17485/DS17487 The DS17485/DS17487 power-control circuitry allows the system to be powered on by an external stimulus such as a keyboard or by a time-and-date (wake-up) alarm. The PWR output pin is triggered by one o.


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