DS1642 Maxim, DS1642 Datasheet

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DS1642

Manufacturer Part Number
DS1642
Description
The DS1642 is a 2k x 8 nonvolatile static RAM and a full-function real-time clock (RTC), both of which are accessible in a bytewide format
Manufacturer
Maxim
Datasheet

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FEATURES
 Integrated NV SRAM, Real-Time Clock,
 Standard JEDEC Bytewide 2k x 8 Static
 Clock Registers are Accessed Identically to
 Totally Nonvolatile with Over 10 Years of
 Access Times of 85ns and 100ns
 Quartz Accuracy ±1 Minute a Month at
 BCD-Coded Year, Month, Date, Day, Hours,
 Power-Fail Write Protection Allows for
 Lithium Energy Source is Electrically
 UL Recognized
ORDERING INFORMATION
+Denotes a lead(Pb)-free/RoHS-compliant package.
A “+" indicates a lead(Pb)-free product. The top mark will include a “+” symbol on lead-free devices.
19-5266; Rev 5/10
www.maxim-ic.com
DS1642-85+
DS1642-100+
Crystal, Power-Fail Control Circuit, and
Lithium Energy Source
RAM Pinout
the Static RAM. These Registers are
Resident in the Eight Top RAM Locations
Operation in the Absence of Power
+25°C, Factory Calibrated
Minutes, and Seconds with Leap Year
Compensation Valid Up to 2100
±10% V
Disconnected to Retain Freshness Until
Power is Applied for the First Time
PART
CC
Power Supply Tolerance
VOLTAGE
RANGE
(V)
5.0
5.0
TEMP RANGE
0°C to +70°C
0°C to +70°C
24 EDIP (0.720a) DS1642+85
24 EDIP (0.720a) DS1642+100
PIN-PACKAGE TOP MARK
1 of 11
Nonvolatile Timekeeping RAM
PIN CONFIGURATION
TOP VIEW
DQ0
DQ1
DQ2
GND
A7
A6
A5
A4
A3
A2
A1
A0
10
1
2
3
4
5
6
7
8
9
11
12
ENCAPSULATED DIP
DS1642
14
24
23
22
20
19
18
17
15
13
16
21
DS1642
V
A8
A9
WE
DQ7
DQ6
DQ5
DQ4
DQ3
OE
A10
CE
CC

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DS1642 Summary of contents

Page 1

... A “+" indicates a lead(Pb)-free product. The top mark will include a “+” symbol on lead-free devices. Nonvolatile Timekeeping RAM PIN CONFIGURATION TOP VIEW DQ0 DQ1 DQ2 GND TEMP RANGE PIN-PACKAGE TOP MARK 0°C to +70°C 24 EDIP (0.720a) DS1642+85 0°C to +70°C 24 EDIP (0.720a) DS1642+100 DS1642 DS1642 ...

Page 2

... CC DESCRIPTION The DS1642 nonvolatile static RAM and a full-function real-time clock (RTC), both of which are accessible in a bytewide format. The nonvolatile time keeping RAM is pin and function equivalent to any JEDEC-standard SRAM. The device can also be easily substituted in ROM, EPROM, and EEPROM sockets, providing read/write nonvolatility and the addition of the real-time clock function ...

Page 3

... CLOCK OPERATIONS–READING THE CLOCK While the double-buffered register structure reduces the chance of reading incorrect data, internal updates to the DS1642 clock registers should be halted before clock data is read to prevent reading of data in transition. However, halting the internal clock register updating process does not affect clock accuracy. ...

Page 4

... The 8th bit of the control register is the write bit. Setting the write bit like the read bit, halts updates to the DS1642 registers. The user can then load them with the correct day, date and time data in 24-hour BCD format. Resetting the write bit then transfers those values to the actual clock counters and allows normal operation to resume ...

Page 5

... The DS1642 has a lithium power source that is designed to provide energy for clock activity, and clock and RAM data retention when the V is sufficient to power the DS1642 continuously for the life of the equipment in which it is installed. For specification purposes, the life expectancy is 10 years at 25C with the internal clock oscillator running in the absence of V power ...

Page 6

... Write Protection Voltage SYMBOL MIN TYP V 2 -0.3 IL SYMBOL MIN TYP CC1 I 1 CC2 2 4.25 4. DS1642 MAX UNITS NOTES MAX UNITS NOTES A +1  0 ...

Page 7

... READ CYCLE TIMING DIAGRAM 85ns ACCESS SYMBOL MIN MAX CEL t 85 CEA t 30 CEZ t 5 OEL t 45 OEA t 30 OEZ 100ns ACCESS UNITS MIN MAX 100 ns 100 100 DS1642 NOTES ...

Page 8

... Data Off Time WE Write Recovery Time 85ns ACCESS SYMBOL MIN MAX WEW t 70 CEW WEZ 100ns ACCESS UNITS MIN MAX 100 DS1642 NOTES ...

Page 9

... WRITE CYCLE TIMING DIAGRAM—WRITE-ENABLE CONTROLLED WRITE CYCLE TIMING DIAGRAM—CHIP-ENABLE CONTROLLED DS1642 ...

Page 10

... Capacitance on All Pins (except DQ) Capacitance on DQ Pins SYMBOL MIN (MIN) t 300 BAT FB (MAX REC SYMBOL MIN TYP MAX UNITS NOTES s s s  years TYP MAX UNITS NOTES DS1642 4, 5 ...

Page 11

... Voltages are referenced to ground. 2) Typical values are at 25C and nominal supplies. 3) Outputs are open. 4) Data retention time is at 25C. 5) Each DS1642 has a built-in switch that disconnects the lithium source until V user. The expected t is defined as a cumulative time in the absence power is first applied by the user ...

Page 12

... For the latest package outline information and land patterns www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 24 EDIP DS1642 24-PIN PACKAGE PACKAGE CODE MDF24+1 PKG DIM. ...

Page 13

... Maxim is a registered trademark of Maxim Integrated Products, Inc. The Dallas logo is a registered trademark of Maxim Integrated Products, Inc. DESCRIPTION © 2010 Maxim Integrated Products DS1642 PAGES CHANGED ...

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