DS1644P120+ datasheet, PDF - EEWORLD Datasheet

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DS1644P120+: DescriptionNonvolatile Timekeeping RAM; File Size301KB，13 Pages; ManufacturerDALLAS; Websitehttp://www.dalsemi.com

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DS1644P120+ Overview

Nonvolatile Timekeeping RAM

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DS1644/DS1644P

Nonvolatile Timekeeping RAM

www.maxim-ic.com

FEATURES

Integrated NV SRAM, Real-Time Clock,

Crystal, Power-Fail Control Circuit and

Lithium Energy Source

Clock Registers are Accessed Identically to

the Static RAM. These Registers are

Resident in the Eight Top RAM Locations.

Totally Nonvolatile with Over 10 Years of

Operation in the Absence of Power

BCD-Coded Year, Month, Date, Day, Hours,

Minutes, and Seconds with Leap Year

Compensation Valid Up to 2100

Power-Fail Write Protection Allows for

±10% V

Power Supply Tolerance

DS1644 Only (DIP Module)

Upward Compatible with the DS1643

Timekeeping RAM to Achieve Higher

RAM Density

Standard JEDEC Bytewide 32k x 8 Static

RAM Pinout

DS1644P Only (PowerCap

Module Board)

Surface Mountable Package for Direct

Connection to PowerCap Containing

Battery and crystal

Replaceable Battery (PowerCap)

Power-Fail Output

Pin-for-Pin Compatible with Other Densities

of DS164XP Timekeeping RAM

Underwriters Laboratory (UL) Recognized

PIN CONFIGURATIONS

A14

A12

DQ0

DQ1

DQ2

GND

A13

A11

A10

DQ7

DQ6

DQ5

DQ4

DQ3

28-Pin Encapsulated Package

(720-mil Extended)

A14

A13

A12

A11

A10

PFO

DQ7

DQ6

DQ5

DQ4

DQ3

DQ2

DQ1

DQ0

GND

GND V

BAT

34-Pin PowerCap Module Board

(Uses DS9034PCX PowerCap)

PowerCap is a registered trademark of Dallas Semiconductor.

ORDERING INFORMATION

PART

DS16440120+

DS16440-120

DS1644P120+

DS1644P-120

VOLTAGE

RANGE (V)

5.0

TEMP RANGE PIN-PACKAGE

0°C to +70°C

32 EDIP (0.740a)

34 PowerCap*

TOP MARK

DS1644+120

DS1644-120

DS1644P+120

DS1644P-120

*DS9034-PCX,

DS9034I-PCX, DS9034-PCX+ required (must be ordered separately).

A “+" indicates a lead-free product. The top mark will include a “+" symbol on lead-free devices.

1 of 13

REV: 040805

DS1644/DS1644P

SETTING THE CLOCK

The MSB Bit, (B7) of the control register is the write bit. Setting the write bit to a 1, like the read bit,

halts updates to the DS1644 registers. The user can then load them with the correct day, date and time

data in 24-hour BCD format. Resetting the write bit to a 0 then transfers those values to the actual clock

counters and allows normal operation to resume.

STOPPING AND STARTING THE CLOCK OSCILLATOR

The clock oscillator may be stopped at any time. To increase the shelf life, the oscillator can be turned off

to minimize current drain from the battery. The

OSC

bit is the MSB for the seconds registers. Setting it to

a 1 stops the oscillator.

FREQUENCY TEST BIT

Bit 6 of the day byte is the frequency test bit. When the frequency test bit is set to logic 1 and the

oscillator is running, the LSB of the seconds register will toggle at 512 Hz. When the seconds register is

being read, the DQ0 line will toggle at the 512 Hz frequency as long as conditions for access remain valid

(i.e.,

low,

low, and address for seconds register remain valid and stable).

CLOCK ACCURACY (DIP MODULE)

The DS1644 is guaranteed to keep time accuracy to within

±1

minute per month at 25°C. The RTC is

calibrated at the factory by Dallas Semiconductor using nonvolatile tuning elements, and does not require

additional calibration. For this reason, methods of field clock calibration are not available and not

necessary. Clock accuracy is also affected by the electrical environment and caution should be taken to

place the RTC in the lowest level EMI section of the PCB layout. For additional information please see

application note 58.

CLOCK ACCURACY (POWERCAP MODULE)

The DS1644 and DS9034PCX are each individually tested for accuracy. Once mounted together, the

module will typically keep time accuracy to within

±1.53

minutes per month (35 ppm) at 25°C. Clock

accuracy is also affected by the electrical environment and caution should be taken to place the RTC in

the lowest level EMI section of the PCB layout. For additional information please see application note

58.

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DS1644P120+ Related Products

	DS1644P120+	DS16440-120	DS16440120+	DS1644+120	DS1644-120	DS1644P+120	DS1644P-120
Description	Nonvolatile Timekeeping RAM	Nonvolatile Timekeeping RAM	Nonvolatile Timekeeping RAM	Nonvolatile Timekeeping RAM	0 TIMER(S), REAL TIME CLOCK, DMA28	Nonvolatile Timekeeping RAM	0 TIMER(S), REAL TIME CLOCK, DMA34

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