DS17885-3+ Maxim Integrated Products, DS17885-3+ Datasheet
DS17885-3+
Specifications of DS17885-3+
Related parts for DS17885-3+
DS17885-3+ Summary of contents
Page 1
... The DS17285, DS17485, DS17885, DS17287, DS17487, and DS17887 real-time clocks (RTCs) are designed to be successors to the industry-standard DS12885 and DS12887. The DS17285, DS17485, and DS17885 (here- after referred to as the DS17x85) provide a real-time clock/calendar, one time-of-day alarm, three maskable interrupts with a common interrupt output, a programma- ble square wave, and 114 bytes of battery-backed NV SRAM ...
Page 2
Real-Time Clocks ABSOLUTE MAXIMUM RATINGS Voltage Range on V Pin Relative to Ground ....-0.3V to +6.0V CC Operating Temperature Range (Noncondensing) Commercial.........................................................0°C to +70°C Industrial ..........................................................-40°C to +85°C Storage Temperature Range EDIP .................................................................-40°C to +85°C PDIP, SO, TSOP.............................................-55°C to +125°C ...
Page 3
DC ELECTRICAL CHARACTERISTICS ( 3.0V Over the operating range, unless otherwise noted.) (Note 1) CC BAT A PARAMETER SYMBOL Current (Oscillator BAT BAUX On +25° 3.0V A ...
Page 4
Real-Time Clocks AC ELECTRICAL CHARACTERISTICS (V = +2.7V to +3.7V Over the operating range, unless otherwise noted.) (Note PARAMETER SYMBOL Cycle Time Pulse Width Low PW Pulse Width High ...
Page 5
ALE PW ASH t ASD RD PW RWH t ASD ASL AD0–AD7 IRQ PF(MAX) V PF(MIN RECOGNIZED CS, WR, RD VALID AD0–AD7 _____________________________________________________________________ Real-Time Clocks t CYC t ASED PW RWL t ...
Page 6
Real-Time Clocks POWER-UP/POWER-DOWN CHARACTERISTICS (T = -40°C to +85°C) (Note 2) A PARAMETER SYMBOL Recovery at Power-Up V Fall Time PF(MAX) V PF(MIN) V Fall Time PF(MAX) V PF(MIN) DATA RETENTION (DS17x87 ONLY) (T ...
Page 7
T = +25°C, unless otherwise noted SUPPLY CURRENT vs. INPUT VOLTAGE 400 350 300 250 200 2.5 2.8 3.0 3.3 3.5 V (V) BAT PIN NAME 24 28 Active-Low Power-On Reset. ...
Page 8
Real-Time Clocks PIN NAME 24 28 Active-Low Chip-Select Input. This pin must be asserted low during a bus cycle for the 13 23 device to be accessed. that take place without asserting Address Latch Enable Input, Active High. This input ...
Page 9
PIN NAME 24 28 Active-Low RAM Clear Input. This pin is used to clear (set to logic 1) all the 114 bytes of general-purpose RAM but does not affect the RAM associated with the real time clock or extended RAM. ...
Page 10
Real-Time Clocks X1 OSCILLATOR X2 DS17x87 ONLY V BAT GND POWER CONTROL BAUX CS BUS WR INTERFACE RD ALE AD0–AD7 DS17x85/87 Figure 1. Functional Diagram 10 ____________________________________________________________________ DIVIDE DIVIDE BY DIVIDE 16:1 MUX ...
Page 11
... RAM. The device also provides additional extended RAM in either 2k/4k/8kbytes (DS17285/DS17485/DS17885). A time- of-day alarm, six maskable interrupts with a common interrupt output, and a programmable square-wave output are available. It also operates in either 24-hour or 12-hour format with an AM/PM indicator ...
Page 12
Real-Time Clocks Power-Down/Power-Up Considerations The RTC function continues to operate, and all the RAM, time, calendar, and alarm memory locations remain nonvolatile regardless of the level of the V input must remain within the minimum BAT BAUX ...
Page 13
The alarm bytes can be used in two ways. First, when the alarm time is written in the appropriate hours, min- utes, and seconds alarm locations, the alarm interrupt is initiated at the specified time each day, if the alarm ...
Page 14
Real-Time Clocks Table 3B. Time, Calendar, and Alarm Data Modes—Binary Mode ( ADDRESS BIT 7 BIT 6 00h 0 0 01h 0 0 02h 0 0 03h 0 0 AM/PM 04h 0 0 AM/PM 05h 0 0 06h ...
Page 15
Bits Rate Selector Bits (RS3 to RS0). These four rate-selection bits select one of the 13 taps on the 15-stage divider or disable the divider output. The tap selected can be used to generate an output square ...
Page 16
Real-Time Clocks Register B (0Bh) MSB BIT 7 BIT 6 BIT 5 SET PIE Bit 7: SET. When the SET bit is 0, the update transfer functions normally by advancing the counts once per second. When the SET bit is ...
Page 17
Register C (0Ch) MSB BIT 7 BIT 6 BIT 5 IRQF PF Bit 7: Interrupt Request Flag (IRQF). This bit is set to 1 when any of the following are true PIE = WIE = ...
Page 18
Real-Time Clocks Nonvolatile RAM The user RAM bytes are not dedicated to any special function within the DS17x85. They can be used by the processor program as battery-backed memory and are fully available during the update cycle. The user RAM ...
Page 19
Periodic Interrupt Selection The periodic interrupt causes the IRQ pin active state from once every 500ms to once every 122µs. This function is separate from the alarm inter- rupt, which can be output from once per ...
Page 20
... Register 47h contains a CRC byte used to validate the data in registers 40h–46h. The CRC polynomial is X bytes of the serial number are read-only registers. The DS17x85/DS17x87 is manufactured such that no two devices contain an identical number in locations 41h–47h. DEVICE DS17285/87 DS17485/87 DS17885/ POLYNOMIAL = 4TH 5TH ...
Page 21
Table 5. Extended Bank Register Bank Definition Bank 0 DV0 = 0 00h Timekeeping and Control 0Dh 0Eh 50 Bytes – User RAM 3Fh 40h 64 Bytes – User RAM 7Fh Note: Reserved bits can be written to any value, ...
Page 22
Real-Time Clocks Century Counter A register has been added in bank 1, location 48H, to keep track of centuries. The value is read in either bina BCD according to the setting of the DM bit. RTC Write Counter ...
Page 23
The timing associated with both the wake-up and kick- starting sequences is illustrated in the Wake- Up/Kickstart Timing Diagram (Figure 6). The timing associated with these functions is divided into five inter- vals, labeled the diagram. ...
Page 24
... KSE), the IRQ line is driven active low in response to enabled event. In addition, the other possible interrupt sources within the DS17885/DS17887 can cause IRQ to be dri- ven low. While system power is applied, the on-chip logic always attempts to drive the PWR pin active in response to the enabled kickstart or wake-up condition ...
Page 25
AS CS AD0-7 53H DS OR R/W Figure 7. Burst Mode Timing Waveform Extended Control Registers Two extended control registers are provided to supply control and status information for the extended func- tions offered by the DS17x85/DS17x87. These are des- ...
Page 26
Real-Time Clocks Extended Control Register (4Bh) MSB BIT 7 BIT 6 BIT 5 ABE E32k Bit 7: Auxiliary Battery Enable (ABE). When written to logic 1, this bit enables the V BAUX functions. Bit 6: Enable 32.768kHz Output (E32k). When ...
Page 27
System Maintenance Interrupt (SMI) Recovery Stack An SMI recovery register stack is located in the extend- ed register bank, locations 4Eh and 4Fh. This register stack, shown below, can be used by the BIOS to recov- er from an SMI ...
Page 28
... PWR X1 X2 N.C. AD0 AD1 AD2 28 ____________________________________________________________________ SQW 22 V BAUX 21 RCLR 20 V BAT 19 IRQ GND ALE DS17285 DS17485 7 DS17885 TSOP Pin Configurations PWR N. SQW N. BAUX AD0 4 21 RCLR AD1 5 20 N.C. DS17287 AD2 6 19 IRQ DS17487 AD3 7 DS17887 18 KS AD4 8 17 ...
Page 29
... DS17485SN-5+ -40°C to +85°C DS17487-3+ 0°C to +70°C DS17487-3IND+ -40°C to +85°C DS17487-5+ 0°C to +70°C DS17487-5IND+ -40°C to +85°C DS17885-3+ 0°C to +70°C DS17885-5+ 0°C to +70°C DS17885E-3+ 0°C to +70°C DS17885E-5+ 0°C to +70°C DS17885EN-3+ -40°C to +85°C DS17885S-3+ 0° ...
Page 30
... Real-Time Clocks Typical Operating Circuit CRYSTAL IRQ ALE WR DS17285 DS17485 RD DS17885 DS83C520 CS AD0–AD7 V SB SUPPLY PWR CONTROL GND CIRCUIT ____________________________________________________________________ PACKAGE V CC DIP SQW SUBSTRATE CONNECTED TO GROUND PROCESS: CMOS RCLR KS For the latest package outline information and land patterns www.maxim-ic.com/packages. Note that a “+”, “#” “ ...
Page 31
... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 31 © 2010 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc ...