DS12885Q各脚功能电路原理芯片引脚定义引脚图及功能IC贸易商-中国IC网-芯三七

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产品型号DS12885Q的概述

芯片DS12885Q的概述 DS12885Q是由德州仪器（Texas Instruments）推出的一款高集成度的实时时钟芯片，广泛用于各种嵌入式系统和电子产品中。该芯片不仅可以提供准确的时间和日期信息，还具有多种辅助功能，包括定时器和中断控制等。DS12885Q主要应用于计算机、通信设备、消费电子和工业控制等领域，因其高可靠性和灵活性而受到工程师的青睐。芯片DS12885Q的详细参数 DS12885Q的主要技术参数包括： - 工作电压: 3V至5.5V - 工作温度范围: -40°C至+85°C - 时钟频率: 32.768 kHz - 低功耗模式: 具有极低的功耗特性，能够在电池供电的环境中长时间运行。 - 非易失性: 具备内部EEPROM存储器，可以在断电状态下保存重要数据。 - 外部中断输入: 可以处理来自多种外部设备的中断请求，提供有效的实时响应能力。厂家、包装与封装 ...

产品型号DS12885Q的Datasheet PDF文件预览

DS12885/DS12885Q/DS12885T

Real-Time Clock

www.maxim-ic.com

FEATURES

§ Drop-in replacement for IBM AT computer

clock/calendar

PIN ASSIGNMENT (Top View)

§ Pin configuration closely matches

MC146818B and DS1285

§ Counts seconds, minutes, hours, days, day of

the week, date, month, and year with leap-

year compensation valid up to 2100

§ Binary or BCD representation of time,

calendar, and alarm

§ 12-hour or 24-hour clock with AM and PM in

12-hour mode

§ Daylight Savings Time option

§ Selectable between Motorola and Intel bus

timing

§ Multiplex bus for pin efficiency

§ Interfaced with software as 128 RAM

locations

DS12885Q

28 PLCC

§ 14 bytes of clock and control registers

§ 114 bytes of general purpose RAM

§ Programmable square-wave output signal

bus-compatible interrupt signals (IRQ )

§ Three interrupts are separately software-

maskable and testable

§ Time-of-day alarm once/second to once/day

§ Periodic rates from 122ms to 500ms

§ End-of-clock update cycle

§ Optional 28-pin PLCC surface mount package

or 32-pin TQFP

DS12885T

32 TQFP

§ Optional industrial temperature range

available

§ Underwriters Laboratory (UL) recognized

Package Dimension Information

http://www.maxim-ic.com/TechSupport/DallasPackInfo.htm

Note:Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device

may be simultaneously available through various sales channels. For information about device errata, click here: http://www.maxim-ic.com/errata.

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072902

DS12885/DS12885Q/DS12885T

DESCRIPTION

The DS12885 real-time clock plus RAM is designed to be a direct replacement for the DS1285. The

DS12885 is identical in form, fit, and function to the DS1285, and has an additional 64 bytes of general

purpose RAM. Access to this additional RAM space is determined by the logic level presented on AD6

during the address portion of an access cycle. An external crystal and battery are the only components

required to maintain time-of-day and memory status in the absence of power. For a complete description

of operating conditions, electrical characteristics, bus timing, and pin descriptions other than X1, X2,

V_BAT, and RCLR , see the DS12887 data sheet.

TYPICAL OPERATING CIRCUIT

ORDERING INFORMATION

PART

DS12885

DS12885N

DS12885S

PIN-PACKAGE

TEMP RANGE

24 DIP

24 SO

28 PLCC

0°C to +70°C

-40°C to +85°C

0°C to +70°C

-40°C to +85°C

0°C to +70°C

-40°C to +85°C

0°C to +70°C

-40°C to +85°C

0°C to +70°C

DS12885N

DS12885Q

DS12885QN

DS12885Q/T&R

DS12885T

DS12885TN

DS12885T/T&R

28 PLCC

28 PLCC/Tape and Reel

32 TQFP

32 TQFP/Tape and Reel

2 of 4

DS12885/DS12885Q/DS12885T

PIN DESCRIPTION

AD0–AD7

N.C.

– Multiplexed Address/Data Bus

IRQ

– Interrupt Request Output

– No Connection

(Open Drain)

– Square-Wave Output

– +5V Supply

– Ground

– 32.768kHz Crystal

Connections

MOT

– Bus Type Selection

SQW

V_CC

GND

X1, X2

– Chip Select

– Address Strobe

R/ W

– Read/Write Input

– Data Strobe

V_BAT

– +3V Battery Input

RESET

– Reset Input

RCLR

– RAM Clear

PIN DESCRIPTION

X1, X2 – Connections for a standard 32.768kHz quartz crystal. The internal oscillator circuitry is

designed for operation with a crystal having a specified load capacitance (C_L) of 6pF. The crystal is

connected directly to the X1 and X2 pins. There is no need for external capacitors or resistors. Note: X1

and X2 are very high-impedance nodes. It is recommended that they and the crystal be guard-ringed with

ground and that high-frequency signals be kept away from the crystal area. For more information about

crystal selection and crystal layout considerations, refer to Application Note 58 “Crystal Considerations

with Dallas Real Time Clocks.”

Oscillator startup times are highly dependent upon crystal characteristics and layout. High ESR and

escessive capactitive loads are the major contributors to long startup times. A circuit using a crystal with

the recommended characteristics and following the recommended layout usually start within one second.

V_BAT– Battery input for any standard 3V lithium cell or other energy source. Battery voltage must be

held between 2.5V and 4V for proper operation. A maximum load of 0.5mA at +25°C in the absence of

power should be used to size the external energy source. Maximum load is measured using a

recommended crystal type connected to X1 and X2.

The battery should be connected directly to the V_BATpin. A diode must not be placed in series with the

battery to the V_BATpin. Furthermore, a diode is not necessary because reverse charging-current protection

circuitry is provided internally to the device and has passed the requirements of Underwriters

Laboratories for UL listing.

See “Conditions of Acceptability” at http://www.maxim-ic.com/TechSupport/QA/ntrl.htm.

RCLR – The RCLR pin is used to clear (set to logic 1) all 114 bytes of general purpose RAM but does

not affect the RAM associated with the real-time clock. In order to clear the RAM, RCLR must be forced

to an input logic “0” (-0.3V to +0.8V) during battery-backup mode when V_CCis not applied. The RCLR

function is designed to be used by human interface (shorting to ground manually or by switch) and not to

be driven with external buffers. This pin is internally pulled up. Do not use an external pullup resistor on

this pin.

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DS12885/DS12885Q/DS12885T

CLOCK ACCURACY

The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the match

between the capacitive load of the oscillator circuit and the capacitive load for which the crystal was

trimmed. Additional error is added by crystal frequency drift caused by temperature shifts. External

circuit noise coupled into the oscillator circuit can result in the clock running fast. Refer to Application

Note 58 “Crystal Considerations with Dallas Real-Time Clocks” for detailed information.

RECOMMENDED LAYOUT FOR CRYSTAL

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DS12885Q产品参数

型号:	DS12885Q
是否无铅：	含铅
是否Rohs认证：	不符合
生命周期：	Active
IHS 制造商：	ROCHESTER ELECTRONICS INC
零件包装代码：	QLCC
包装说明：	QCCJ,
针数：	28
Reach Compliance Code：	unknown
风险等级：	5.7
Is Samacsys：	N
其他特性：	DAYLIGHT SAVINGS OPTION; SELECTABLE MOTOROLA/INTEL TIMING
最大时钟频率：	0.032 MHz
外部数据总线宽度：	8
信息访问方法：	PARALLEL, MUXED BUS
JESD-30 代码：	S-PQCC-J28
JESD-609代码：	e0
长度：	11.505 mm
湿度敏感等级：	1
端子数量：	28
计时器数量：	1
最高工作温度：	70 °C
最低工作温度：
封装主体材料：	PLASTIC/EPOXY
封装代码：	QCCJ
封装形状：	SQUARE
封装形式：	CHIP CARRIER
峰值回流温度（摄氏度）：	245
认证状态：	COMMERCIAL
座面最大高度：	4.57 mm
最大供电电压：	5.5 V
最小供电电压：	4.5 V
标称供电电压：	5 V
表面贴装：	YES
技术：	CMOS
温度等级：	COMMERCIAL
端子面层：	TIN LEAD
端子形式：	J BEND
端子节距：	1.27 mm
端子位置：	QUAD
处于峰值回流温度下的最长时间：	NOT SPECIFIED
宽度：	11.505 mm
uPs/uCs/外围集成电路类型：	TIMER, REAL TIME CLOCK
Base Number Matches：	1

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