DS1306 datasheet(3/20 Pages) DALLAS

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DS1306

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SIGNAL DESCRIPTIONS

VCC1 - DC power is provided to the device on this pin. VCC1 is the primary power supply.

VCC2 - This is the secondary power supply pin. In systems using the trickle charger, the rechargeable

energy source is connected to this pin.

VBAT - Battery input for any standard 3-volt lithium cell or other energy source.

VCCIF (Interface Logic Power Supply Input) - The VCCIF pin allows the DS1306 to drive SDO and

32 kHz output pins to a level that is compatible with the interface logic, thus allowing an easy interface to

3-volt logic in mixed supply systems. This pin is physically connected to the source connection of the p-

channel transistors in the output buffers of the SDO and 32 kHz pins.

SERMODE (Serial Interface Mode Input) - The SERMODE pin offers the flexibility to choose

between two serial interface modes.

When connected to GND, standard 3-wire communication is

selected. When connected to VCC, Motorola SPI communication is selected.

SCLK (Serial Clock Input) - SCLK is used to synchronize data movement on the serial interface for

either the SPI or 3-wire interface.

SDI (Serial Data Input) - When SPI communication is selected, the SDI pin is the serial data input for

the SPI bus. When 3-wire communication is selected, this pin must be tied to the SDO pin (the SDI and

SDO pins function as a single I/O pin when tied together).

SDO (Serial Data Output) - When SPI communication is selected, the SDO pin is the serial data output

for the SPI bus. When 3-wire communication is selected, this pin must be tied to the SDI pin (the SDI

and SDO pins function as a single I/O pin when tied together).

CE (Chip Enable) - The Chip Enable signal must be asserted high during a read or a write for both

3-wire and SPI communication. This pin has an internal 55k pull-down resistor (typical).

INT0

(Interrupt 0 Output) - The INT0 pin is an active low output of the DS1306 that can be used as an

interrupt input to a processor. The INT0 pin can be programmed to be asserted by Alarm 0. The INT0

pin remains low as long as the status bit causing the interrupt is present and the corresponding interrupt

enable bit is set. The INT0 pin operates when the DS1306 is powered by VCC1, VCC2, or VBAT. The INT0

pin is an open drain output and requires an external pullup resistor.

1 Hz (1 Hz Clock Output) - The 1 Hz pin provides a 1 Hz squarewave output. This output is active

when the 1 Hz bit in the control register is a logic 1.

Both INT0 and 1 Hz pins are open drain outputs. The interrupt, 1 Hz signal, and the internal clock

continue to run regardless of the level of VCC (as long as a power source is present).

INT1 (Interrupt 1 Output) - The INT1 pin is an active high output of the DS1306 that can be used as an

interrupt input to a processor. The INT1 pin can be programmed to be asserted by alarm 1. When an

alarm condition is present, the INT1 pin generates a 62.5 ms active high pulse. The INT1 pin operates

only when the DS1306 is powered by VCC2 or VBAT. When active, the INT1 pin is internally pulled up to

VCC2 or VBAT. When inactive, the INT1 pin is internally pulled low.

DS1306 Datasheet(PDF) 3 Page - Dallas Semiconductor