DS17485N-3 datasheet, PDF - EEWORLD Datasheet

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DS17485N-3: DescriptionReal Time Clock, Volatile, 1 Timer(s), CMOS, PDIP24, DIP-24; CategoryThe embedded processor and controller Microcontrollers and processors; File Size422KB，38 Pages; ManufacturerMaxim; Websitehttps://www.maximintegrated.com/en.html

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DS17485N-3 Overview

Real Time Clock, Volatile, 1 Timer(s), CMOS, PDIP24, DIP-24

DS17485N-3 Parametric

Parameter Name	Attribute value
Is it lead-free?	Contains lead
Is it Rohs certified?	incompatible
Maker	Maxim
Parts packaging code	DIP
package instruction	DIP-24
Contacts	24
Reach Compliance Code	_compli
ECCN code	EAR99
maximum clock frequency	0.032 MHz
External data bus width	8
Information access methods	PARALLEL, MUXED BUS
interrupt capability	Y
JESD-30 code	R-PDIP-T24
JESD-609 code	e0
length	31.75 mm
Number of terminals	24
Number of timers	1
Maximum operating temperature	85 °C
Minimum operating temperature	-40 °C
Package body material	PLASTIC/EPOXY
encapsulated code	DIP
Encapsulate equivalent code	DIP24,.6
Package shape	RECTANGULAR
Package form	IN-LINE
Peak Reflow Temperature (Celsius)	NOT SPECIFIED
power supply	3 V
Certification status	Not Qualified
Maximum seat height	5.08 mm
Maximum supply voltage	3.3 V
Minimum supply voltage	2.7 V
Nominal supply voltage	3 V
surface mount	NO
technology	CMOS
Temperature level	INDUSTRIAL
Terminal surface	Tin/Lead (Sn/Pb)
Terminal form	THROUGH-HOLE
Terminal pitch	2.54 mm
Terminal location	DUAL
shortest time	SECONDS
Maximum time at peak reflow temperature	NOT SPECIFIED
Volatile	YES
width	15.24 mm
uPs/uCs/peripheral integrated circuit type	TIMER, REAL TIME CLOCK
Base Number Matches	1

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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

AD0

AD1

AD2

AD3

AD4

AD5

AD6

AD7

GND

SQW

BAUX

RCLR

BAT

IRQ

GND

ALE

DS17485 24-Pin DIP

DS17485S 24-Pin SO

PWR

AD0

AD1

AD2

AD3

AD4

AD5

AD6

AD7

GND

SQW

BAUX

RCLR

IRQ

ALE

DS17487 24-Pin

Encapsulated Package

TYPICAL OPERATING CIRCUIT

IRQ

BAT

RCLR

BAUX

SQW

PWR

ADO

AD1

AD2

GND

ALE

GND

AD7

AD6

AD5

AD4

AD3

DS17485E 28-Pin TSOP

1 of 38

050802

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 or either of these events, and is used to turn on an external power supply. The

PWR

pin is under

software control, so that when a task is complete, the system power can then be shut down.

The DS17485 is a clock/calendar chip with the features described above. An external crystal and battery

are the only components required to maintain time-of-day and memory status in the absence of power.

The DS17487 incorporates the DS17485 chip, a 32.768kHz crystal, and a lithium battery in a complete,

self-contained timekeeping module. The entire unit is fully tested at Dallas Semiconductor such that a

minimum of 10 years of timekeeping and data retention in the absence of V

is guaranteed.

OPERATION

The block diagram in Figure 1 shows the pin connections with the major internal functions of the

DS17485/DS17487. The following paragraphs describe the function of each pin.

SIGNAL DESCRIPTIONS

GND, V

–

DC power is provided to the device on these pins. V

is the +3V or +5V input.

SQW – Square-Wave Output.

The SQW pin provides a 32kHz square-wave output, t

REC

, after a power-

up condition has been detected. This condition sets the following bits, enabling the 32kHz output;

DV1 = 1, and E32k = 1. A square wave is output on this pin if either SQWE = 1 or E32k = 1. If E32k = 1,

then 32kHz is output regardless of the other control bits. If E32k = 0, then the output frequency is

dependent on the control bits in register A. The SQW pin can output a signal from one of 13 taps

provided by the 15 internal divider stages of the RTC. The frequency of the SQW pin can be changed by

programming Register A, as shown in Table 2. The SQW signal can be turned on and off using the

SQWE bit in register B or the E32k bit in extended register 4Bh. A 32kHz SQW signal is output when the

enable 32kHz (E32k) bit in extended register 4Bh is a logic 1 and V

is above V

. A 32kHz square

wave is also available when V

is less than V

if E32k = 1, ABE = 1, and voltage is applied to the

BAUX

pin.

AD0 to AD7 – Multiplexed Bidirectional Address/Data Bus.

Multiplexed buses save pins because

address information time and data information time share the same signal paths. The addresses are

present during the first portion of the bus cycle and the same pins and signal paths are used for data in the

second portion of the cycle. Address/data multiplexing does not slow the access time of the DS17485

since the bus change from address to data occurs during the internal RAM access time. Addresses must

be valid prior to the latter portion of ALE, at which time the DS17485/DS17487 latches the address.

Valid write data must be present and held stable during the latter portion of the

pulse. In a read cycle

the DS17485/DS17487 outputs 8 bits of data during the latter portion of the

pulse. The read cycle is

terminated and the bus returns to a high impedance state as

transitions high. The address/data bus

also serves as a bidirectional data path for the external extended RAM.

ALE – RTC Address Strobe Input; Active High.

A pulse on the address strobe pin serves to

demultiplex the bus. The falling edge of ALE causes the RTC address to be latched within the

DS17485/DS17487.

–RTC

Read Input; Active Low.

identifies the time period when the DS17485/DS17487 drives

the bus with RTC read data. The

signal is an enable signal for the output buffers of the clock.

3 of 38

DS17485N-3 Related Products

	DS17485N-3	DS17485N-5
Description	Real Time Clock, Volatile, 1 Timer(s), CMOS, PDIP24, DIP-24	Real Time Clock, Volatile, 1 Timer(s), CMOS, PDIP24, DIP-24
Is it lead-free?	Contains lead	Contains lead
Is it Rohs certified?	incompatible	incompatible
Maker	Maxim	Maxim
Parts packaging code	DIP	DIP
package instruction	DIP-24	DIP-24
Contacts	24	24
Reach Compliance Code	_compli	_compli
ECCN code	EAR99	EAR99
maximum clock frequency	0.032 MHz	0.032 MHz
External data bus width	8	8
Information access methods	PARALLEL, MUXED BUS	PARALLEL, MUXED BUS
interrupt capability	Y	Y
JESD-30 code	R-PDIP-T24	R-PDIP-T24
JESD-609 code	e0	e0
length	31.75 mm	31.75 mm
Number of terminals	24	24
Number of timers	1	1
Maximum operating temperature	85 °C	85 °C
Minimum operating temperature	-40 °C	-40 °C
Package body material	PLASTIC/EPOXY	PLASTIC/EPOXY
encapsulated code	DIP	DIP
Encapsulate equivalent code	DIP24,.6	DIP24,.6
Package shape	RECTANGULAR	RECTANGULAR
Package form	IN-LINE	IN-LINE
Peak Reflow Temperature (Celsius)	NOT SPECIFIED	NOT SPECIFIED
power supply	3 V	5 V
Certification status	Not Qualified	Not Qualified
Maximum seat height	5.08 mm	5.08 mm
Maximum supply voltage	3.3 V	5.5 V
Minimum supply voltage	2.7 V	4.5 V
Nominal supply voltage	3 V	5 V
surface mount	NO	NO
technology	CMOS	CMOS
Temperature level	INDUSTRIAL	INDUSTRIAL
Terminal surface	Tin/Lead (Sn/Pb)	Tin/Lead (Sn/Pb)
Terminal form	THROUGH-HOLE	THROUGH-HOLE
Terminal pitch	2.54 mm	2.54 mm
Terminal location	DUAL	DUAL
shortest time	SECONDS	SECONDS
Maximum time at peak reflow temperature	NOT SPECIFIED	NOT SPECIFIED
Volatile	YES	YES
width	15.24 mm	15.24 mm
uPs/uCs/peripheral integrated circuit type	TIMER, REAL TIME CLOCK	TIMER, REAL TIME CLOCK
Base Number Matches	1	1

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