DS3231 查看數據表（PDF） - Dallas Semiconductor -> Maxim Integrated

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DS3231

Extremely Accurate I2C-Integrated RTC/TCXO/Crystal

Dallas Semiconductor -> Maxim Integrated 

Extremely Accurate I2C-Integrated

RTC/TCXO/Crystal

Pin Description

PIN

1

2

3

4

5–12

13

14

15

16

NAME

32kHz

VCC

FUNCTION

32kHz Output. This open-drain pin requires an external pullup resistor. It may be left open if not used.

DC Power Pin for Primary Power Supply. This pin should be decoupled using a 0.1µF to 1.0µF capacitor.

If not used, connect to ground.

INT/SQW

Active-Low Interrupt or Square-Wave Output. This open-drain pin requires an external pullup resistor. It may be

left open if not used. This multifunction pin is determined by the state of the INTCN bit in the Control Register

(0Eh). When INTCN is set to logic 0, this pin outputs a square wave and its frequency is determined by RS2

and RS1 bits. When INTCN is set to logic 1, then a match between the timekeeping registers and either of the

alarm registers activates the INT/SQW pin (if the alarm is enabled). Because the INTCN bit is set to logic 1

when power is first applied, the pin defaults to an interrupt output with alarms disabled.

RST

N.C.

GND

Active-Low Reset. This pin is an open-drain input/output. It indicates the status of VCC relative to the

VPF specification. As VCC falls below VPF, the RST pin is driven low. When VCC exceeds VPF, for tRST, the RST

pin is driven high impedance. The active-low, open-drain output is combined with a debounced pushbutton

input function. This pin can be activated by a pushbutton reset request. It has an internal 50kΩ nominal value

pullup resistor to VCC. No external pullup resistors should be connected. If the crystal oscillator is disabled, the

startup time of the oscillator is added to the tRST delay.

No Connection. Must be connected to ground.

Ground

VBAT

Backup Power-Supply Input. This pin should be decoupled using a 0.1µF to 1.0µF low-leakage capacitor.

If the I2C interface is inactive whenever the device is powered by the VBAT input, the decoupling capacitor is

not required. If VBAT is not used, connect to ground. UL recognized to ensure against reverse charging when

used with a lithium battery. Go to www.maxim-ic.com/qa/info/ul.

SDA

SCL

Serial Data Input/Output. This pin is the data input/output for the I2C serial interface. This open-drain pin

requires an external pullup resistor.

Serial Clock Input. This pin is the clock input for the I2C serial interface and is used to synchronize data

movement on the serial interface.

Detailed Description

The DS3231 is a serial RTC driven by a temperature-

compensated 32kHz crystal oscillator. The TCXO pro-

vides a stable and accurate reference clock, and

maintains the RTC to within ±2 minutes per year accu-

racy from -40°C to +85°C. The TCXO frequency output

is available at the 32kHz pin. The RTC is a low-power

clock/calendar with two programmable time-of-day

alarms and a programmable square-wave output. The

INT/SQW provides either an interrupt signal due to

alarm conditions or a square-wave output. The clock/cal-

endar provides seconds, minutes, hours, day, date,

month, and year information. The date at the end of the

month is automatically adjusted for months with fewer

than 31 days, including corrections for leap year. The

clock operates in either the 24-hour or 12-hour format

with an AM/PM indicator. The internal registers are

accessible though an I2C bus interface.

A temperature-compensated voltage reference and

comparator circuit monitors the level of VCC to detect

power failures and to automatically switch to the back-

up supply when necessary. The RST pin provides an

external pushbutton function and acts as an indicator

of a power-fail event.

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