DS1305E View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS1305E

Serial Alarm Real Time Clock (RTC)

Dallas Semiconductor -> Maxim Integrated 

DS1305

SERIAL PERIPHERAL INTERFACE (SPI)

The serial peripheral interface (SPI) is a synchronous bus for address and data transfer and is used when

interfacing with the SPI bus on specific Motorola microcontrollers such as the 68HC05C4 and the

68HC11A8. The SPI mode of serial communication is selected by tying the SERMODE pin to VCC.

Four pins are used for the SPI. The four pins are the SDO (Serial Data Out), SDI (Serial Data In), CE

(Chip Enable) and SCLK (Serial Clock). The DS1305 is the slave device in an SPI application, with the

microcontroller being the master.

The SDI and SDO pins are the serial data input and output pins for the DS1305, respectively. The CE

input is used to initiate and terminate a data transfer. The SCLK pin is used to synchronize data

movement between the master (microcontroller) and the slave (DS1305) devices.

The shift clock (SCLK), which is generated by the microcontroller, is active only during address and data

transfer to any device on the SPI bus. The inactive clock polarity is programmable in some

microcontrollers. The DS1305 offers an important feature in that the level of the inactive clock is

determined by sampling SCLK when CE becomes active. Therefore either SCLK polarity can be

accommodated. Input data (SDI) is latched on the internal strobe edge and output data (SDO) is shifted

out on the shift edge (see Table 3 and Figure 6). There is one clock for each bit transferred. Address and

data bits are transferred in groups of eight.

POWER SUPPLY CONFIGURATIONS FOR THE DS1305 Figure 5

Configuration 1: Backup Supply is a Non-Rechargeable Lithium Battery

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