DS3231MZ 查看數據表（PDF） - Maxim Integrated

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DS3231MZ

±5ppm, I2C Real-Time Clock

Maxim Integrated 

±5ppm, I2C Real-Time Clock

+3.3V

VCC

VBAT

Figure 4. Single Supply (VCC Only)

VCC

VBAT

Figure 5. Single Supply (VBAT Only)

+3.3V

VCC

VBAT

Figure 6. Dual Power Supply

Table 1. Power Control

CONFIGURATION

VCC Only

(Figure 4)

VBAT Only

(Figure 5)

Dual Supply

(Figure 6)

CONDITION

VCC > VPF

VCC < VPF

EOSC = 0

EOSC = 1

VCC > VPF

VCC < VPF

High-Accuracy Time Base

The temperature sensor, oscillator, and digital adjust-

ment controller logic form the highly accurate time base.

The controller reads the output of the on-board tempera-

ture sensor and adjusts the final 1Hz output to maintain

the required accuracy. The device is trimmed at the

factory to maintain a tight accuracy over the operating

temperature range. When the device is powered by VCC,

the adjustment occurs once a second. When the device

is powered by VBAT, the adjustment occurs once every

10s to conserve power. Adjusting the 1Hz time base less

often does not affect the device’s long-term timekeeping

accuracy. The device also contains an Aging Offset reg-

ister that allows a constant offset (positive or negative) to

be added to the factory-trimmed adjustment value.

Power-Supply Configurations

The DS3231M can be configured to operate on a single

power supply (using either VCC or VBAT) or in a dual-

supply configuration, which provides a backup supply

source to keep the timekeeping circuits alive during

absence of primary system power.

Figure 4 illustrates a single-supply configuration using

VCC only, with the VBAT input grounded. When VCC < VPF,

the RST output is asserted (active low). Temperature

conversions are executed once per second.

Figure 5 illustrates a single-supply configuration using

VBAT only, with the VCC input grounded. The RST output

is disabled and is held at ground through the connection

of the internal pullup resistor. Temperature conversions

are executed once every 10s.

Figure 6 illustrates a dual-supply configuration, using

the VCC supply for normal system operation and the

VBAT supply for backup power. In this configuration, the

power-selection function is provided by a temperature-

compensated voltage reference and a comparator circuit

that monitors the VCC level. When VCC is greater than

VPF, the device is powered by VCC. When VCC is less

than VPF but greater than VBAT, the device is powered

I/O ACTIVE

ICCA

IBATA

ICCA

VCC > VBAT

VCC < VBAT

ICCA

IBATA

I/O INACTIVE

ICCS

IBATT

IBATDR

ICCS

VCC > VBAT

VCC < VBAT

ICCS

IBATT

RST

Inactive (High)

Active (Low)

Disabled (Low)

Inactive (High)

Active (Low)

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