DS1305EN - Dallas Semiconductor

1 of 22 092801

FEATURES

§ Real-time clock (RTC) counts seconds,

minutes, hours, date of the month, month,

day of the week, and year with leap-year

compensation valid up to 2100

§ 96-byte, battery-backed, nonvolatile (NV)

RAM for data storage

§ Two time-of-day alarms—programmable on

combination of seconds, minutes, hours, and

day of the week

§ Serial interface supports Motorola Serial

Peripheral Interface (SPI) serial data ports or

standard 3-wire interface

§ Burst mode for reading/writing successive

addresses in clock/RAM

§ Dual-power supply pins for primary and

backup power supplies

§ Optional trickle charge output to backup

supply

§ 2.0V to 5.5V operation

§ Optional industrial temperature range:

-40°C to +85°C

§ Available in space-efficient, 20-pin TSSOP

package

§ Underwriters Laboratory (UL) recognized

ORDERING INFORMATION

DS1305 16-Pin DIP (300-mil)

DS1305N 16-Pin DIP (Industrial)

DS1305E 20-Pin TSSOP (173-mil)

DS1305EN 20-Pin TSSOP (Industrial)

PIN ASSIGNMENT

DS1305

Serial Alarm Real-Time Clock

www.maxim-ic.com

VCC2 120V

CC1

VBAT 219NC

X1 3 18 PF

NC 4 17 VCCIF

X2 5 16 SD0

NC 6 15 SDI

INT0 7 14 SCLK

NC 8 13 NC

INT1 9 12 CE

GND 10 11 SERMODE

DS1305 20-Pin TSSOP (173-mil)

VCC2 1 16 VCC1

VBAT 215PF

X1 3 14 VCCIF

X2 4 13 SDO

NC 5 12 SDI

INT0 6 11 SCLK

INT1 7 10 CE

GND 8 9 SERMODE

DS1305 16-Pin DIP (300-mil)

DS1305

2 of 22

PIN DESCRIPTION

VCC1 - Primary Power Supply

VCC2 - Backup Power Supply

VBAT - +3V Battery Input

VCCIF - Interface Logic Power Supply Input

GND - Ground

X1, X2 - 32,768kHz Crystal Connection

INT0 - Interrupt 0 Output

INT1 - Interrupt 1 Output

SDI - Serial Data In

SDO - Serial Data Out

CE - Chip Enable

SCLK - Serial Clock

SERMODE - Serial Interface Mode

PF - Power-Fail Output

DESCRIPTION

The DS1305 Serial Alarm Real-Time Clock provides a full binary-coded decimal (BCD) clock calendar

that is accessed via a simple serial interface. The clock/calendar provides seconds, minutes, hours, day,

date, month, and year information. The end of the month date 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 AM/PM indicator. In addition, 96 bytes of nonvolatile RAM are provided for data

storage.

An interface logic power supply input pin (VCCIF) allows the DS1305 to drive SDO and PF pins to a level

that is compatible with the interface logic. This allows an easy interface to 3V logic in mixed supply

systems.

The DS1305 offers dual-power supplies as well as a battery input pin. The dual power supplies support a

programmable trickle charge circuit that allows a rechargeable energy source (such as a super cap or

rechargeable battery) to be used for a backup supply. The VBAT pin allows the device to be backed up by

a non-rechargeable battery. The DS1305 is fully operational from 2.0V to 5.5V.

Two programmable time-of-day alarms are provided by the DS1305. Each alarm can generate an

interrupt on a programmable combination of seconds, minutes, hours, and day. “Don’t care” states can be

inserted into one or more fields if it is desired for them to be ignored for the alarm condition. The time-of-

day alarms can be programmed to assert two different interrupt outputs or to assert one common interrupt

output. Both interrupt outputs operate when the device is powered by VCC1, VCC2, or VBAT.

The DS1305 supports a direct interface to Motorola SPI serial data ports or standard 3-wire interface. A

straightforward address and data format is implemented in which data transfers can occur 1 byte at a time

or in multiple-byte burst mode.

OPERATION

The block diagram in Figure 1 shows the main elements of the serial alarm RTC. The following

paragraphs describe the function of each pin.

DS1305

3 of 22

DS1305 BLOCK DIAGRAM Figure 1

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 3V lithium cell or other energy source. UL recognized to ensure

against reverse charging current when used in conjunction with a lithium battery.

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

VCCIF (Interface Logic Power Supply Input) – The VCCIF pin allows the DS1305 to drive SDO and PF

output pins to a level that is compatible with the interface logic, thus allowing an easy interface to 3V

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 PF 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).

DS1305

4 of 22

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 DS1305 that can be used as an

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

programmed to be asserted by either Alarm 0 or Alarm 1. 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 DS1305 is powered by VCC1, VCC2, or VBAT. The INT0 pin is an open drain output and requires

an external pull-up resistor.

INT1 (Interrupt 1 Output) – The INT1 pin is an active low output of the DS1305 that can be used as an

interrupt input to a processor. The INT1 pin can be programmed to be asserted by Alarm 1 only. The

INT1 pin remains low as long as the status bit causing the interrupt is present and the corresponding

interrupt enable bit is set. The INT1 pin operates when the DS1305 is powered by VCC1, VCC2, or VBAT.

The INT1 pin is an open drain output and requires an external pull-up resistor.

Both INT0 and INT1 are open drain outputs. The two interrupts and the internal clock continue to run

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

PF (Power Fail Output) – The PF pin is used to indicate loss of the primary power supply (VCC1). When

VCC1 is less than VCC2 or is less than VBAT , the PF pin will be driven low.

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

operation with a crystal having a specified load capacitance of 6pF. For more information on crystal

selection and crystal layout considerations, please consult Application Note 58, “Crystal Considerations

with Dallas Real-Time Clocks.” The DS1305 can also be driven by an external 32.768kHz oscillator. In

this configuration, the X1 pin is connected to the external oscillator signal and the X2 pin is floated.

RECOMMENDED LAYOUT FOR CRYSTAL

DS1305

5 of 22

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 will be added by crystal frequency drift caused by temperature shifts. External

circuit noise coupled into the oscillator circuit may result in the clock running fast. See Application Note

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

CLOCK, CALENDAR, AND ALARM

The time and calendar information is obtained by reading the appropriate register bytes. The RTC

registers and user RAM are illustrated in Figure 2. The time, calendar, and alarm are set or initialized by

writing the appropriate register bytes. Note that some bits are set to zero. These bits will always read 0

regardless of how they are written. Also note that registers 12h to 1Fh (read) and registers 92h to 9Fh are

reserved. These registers will always read 0 regardless of how they are written. The contents of the time,

calendar, and alarm registers are in the BCD format.

Except where otherwise noted, the initial power on state of all registers is not defined. Therefore, it is

important to enable the oscillator (EOSC = 0) and disable write protect (WP = 0) during initial

configuration.

RTC REGISTERS AND ADDRESS MAP Figure 2

HEX ADDRESS

READ WRITE Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 RANGE

00H 80H 0 10 SEC SEC 00-99

01H 81H 0 10 MIN MIN 00-59

P 01-12 + P/A12

02H 82H 0

24 10

10 HR HOURS

00-23

03H 83H 0 0 0 0 DAY 1-7

04H 84H 0 0 10 DATE DATE 1-31

05H 85H 0 0 10 MONTH MONTH 01-12

06H 86H 10 YEAR YEAR 00-99

Alarm 0

07H 87H M 10 SEC ALARM SEC ALARM 00-59

08H 88H M 10 MIN ALARM MIN ALARM 00-59

P12

01-12 + P/A09H 89H M

24 10

10 HR HOUR ALARM

00-23

0AH 8AH M 0 0 0 DAY ALARM 01-07

Alarm 1

0BH 8BH M 10 SEC ALARM SEC ALARM 00-59

0CH 8CH M 10 MIN ALARM MIN ALARM 00-59

P12

01-12 + P/A0DH 8DH M

24 10

10 HR HOUR ALARM

00-23

0EH 8EH M 0 0 0 DAY ALARM 01-07

0FH 8FH CONTROL REGISTER

10H 90H STATUS REGISTER

11H 91H TRICKLE CHARGER REGISTER

12-1FH 92-9FH RESERVED

20-7FH A0-FFH 96 BYTES USER RAM 00-FF

NOTE:

1. Range for alarm registers does not include mask’m’ bits.

DS1305

6 of 22

The DS1305 can be run in either 12-hour or 24-hour mode. Bit 6 of the hours register is defined as the

12- or 24-hour mode select bit. When high, the 12-hour mode is selected. In the 12-hour mode, bit 5 is the

AM/PM bit with logic high being PM. In the 24-hour mode, bit 5 is the second 10-hour bit (20–23 hours).

The DS1305 contains two time-of-day alarms. Time-of-day alarm 0 can be set by writing to registers 87h

to 8Ah. Time-of-day alarm 1 can be set by writing to registers 8Bh to 8Eh. The alarms can be

programmed (by the INTCN bit of the control register) to operate in two different modes; each alarm can

drive its own separate interrupt output or both alarms can drive a common interrupt output. Bit 7 of each

of the time-of-day alarm registers are mask bits (Table 1). When all of the mask bits are logic 0, a time-

of-day alarm will only occur once per week when the values stored in timekeeping registers 00h to 03h

match the values stored in the time-of-day alarm registers. An alarm will be generated every day when bit

7 of the day alarm register is set to a logic 1. An alarm will be generated every hour when bit 7 of the day

and hour alarm registers is set to a logic 1. Similarly, an alarm will be generated every minute when bit 7

of the day, hour, and minute alarm registers is set to a logic 1. When bit 7 of the day, hour, minute, and

seconds alarm registers is set to a logic 1, alarm will occur every second.

DS1305

7 of 22

TIME-OF-DAY ALARM MASK BITS Table 1

ALARM REGISTER MASK BITS (BIT 7)

SECONDS MINUTES HOURS DAYS

1 1 1 1 Alarm once per second

0 1 1 1 Alarm when seconds match

0 0 1 1 Alarm when minutes and seconds match

0 0 0 1 Alarm hours, minutes and seconds match

0 0 0 0 Alarm day, hours, minutes and seconds match

SPECIAL PURPOSE REGISTERS

The DS1305 has three additional registers (control register, status register, and trickle charger register)

that control the real-time clock, interrupts, and trickle charger.

CONTROL REGISTER (READ 0FH, WRITE 8FH)

BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0

EOSC WP 0 0 0 INTCN AIE1 AIEO

EOSC (Enable Oscillator) – This bit when set to logic 0 will start the oscillator. When this bit is set to a

logic 1, the oscillator is stopped and the DS1305 is placed into a low-power standby mode with a current

drain of less than 100 nanoamps when power is supplied by VBAT or VCC2. The initial power on state is

not defined.

WP (Write Protect) – Before any write operation to the clock or RAM, this bit must be logic 0. When

high, the write protect bit prevents a write operation to any register, including bits 0, 1, 2, and 7 of the

control register. Upon initial power-up, the state of the WP bit is undefined. Therefore, the WP bit

should be cleared before attempting to write to the device.

INTCN (Interrupt Control) – This bit controls the relationship between the two time-of-day alarms and

the interrupt output pins. When the INTCN bit is set to a logic 1, a match between the timekeeping

registers and the alarm 0 registers will activate the INT0 pin (provided that the alarm is enabled) and a

match between the timekeeping registers and the alarm 1 registers will activate the INT1 pin (provided

that the alarm is enabled). When the INTCN bit is set to a logic 0, a match between the timekeeping

registers and either alarm 0 or alarm 1 will activate the INT0 pin (provided that the alarms are enabled).

INT1 has no function when INTCN is set to a logic 0.

AIE0 (Alarm Interrupt Enable 0) – When set to a logic 1, this bit permits the interrupt 0 request flag

(IRQF0) bit in the status register to assert INT0 . When the AIE0 bit is set to logic 0, the IRQF0 bit does

not initiate the INT0 signal.

AIE1 (Alarm Interrupt Enable 1) – When set to a logic 1, this bit permits the interrupt 1 request flag

(IRQF1) bit in the status register to assert INT1 (when INTCN = 1) or to assert INT0 (when INTCN = 0).

When the AIE1 bit is set to logic 0, the IRQF1 bit does not initiate an interrupt signal.

STATUS REGISTER (READ 10H)

BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0

000000IRQF1IRQF0

DS1305

8 of 22

IRQF0 (Interrupt 0 Request Flag) – A logic 1 in the interrupt request flag bit indicates that the current

time has matched the alarm 0 registers. If the AIE0 bit is also a logic 1, the INT0 pin will go low. IRQF0

is cleared when the address pointer goes to any of the alarm 0 registers during a read or write.

IRQF1 (Interrupt 1 Request Flag) – A logic 1 in the interrupt request flag bit indicates that the current

time has matched the alarm 1 registers. This flag can be used to generate an interrupt on either INT0 or

INT1 depending on the status of the INTCN bit in the control Register. If the INTCN bit is set to a logic 1

and IRQF1 is at a logic 1 (and AIE1 bit is also a logic 1), the INT1 pin will go low. If the INTCN bit is

set to a logic 0 and IRQF1 is at a logic 1 (and AIE1 bit is also a logic 1), the INT0 pin will go low. IRQF1

is cleared when the address pointer goes to any of the alarm 1 registers during a read or write.

TRICKLE CHARGE REGISTER (READ 11H, WRITE 91H)

This register controls the trickle charge characteristics of the DS1305. The simplified schematic of Figure

3 shows the basic components of the trickle charger. The trickle charge select (TCS) bits (bits 4-7)

control the selection of the trickle charger. In order to prevent accidental enabling, only a pattern of 1010

will enable the trickle charger. All other patterns will disable the trickle charger. On the initial application

of power, the DS1305 powers up with the trickle charger disabled. The diode select (DS) bits (bits 2-3)

select whether one diode or two diodes are connected between VCC1 and VCC2. The resistor select (RS)

bits select the resistor that is connected between VCC1 and VCC2. The resistor and diodes are selected by

the RS and DS bits as shown in Table 2.

PROGRAMMABLE TRICKLE CHARGER Figure 3

DS1305

9 of 22

TRICKLE CHARGER RESISTOR & DIODE SELECT Table 2

TCS

Bit 7

TCS

Bit 6

TCS

Bit 5

TCS

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

FUNCTION

XXXXXX00 Disabled

XXXX00XX Disabled

XXXX11XX Disabled

1 0 1 0 0101 1 Diode, 2kΩ

1 0 1 0 0110 1 Diode, 4kΩ

1 0 1 0 0111 1 Diode, 8kΩ

1 0 1 0 1001 2 Diodes, 2kΩ

1 0 1 0 1010 2 Diodes, 4kΩ

1 0 1 0 1011 2 Diodes, 8kΩ

Diode and resistor selection is determined by the user according to the maximum current desired for

battery or super cap charging. The maximum charging current can be calculated as illustrated in the

following example. Assume that a system power supply of 5V is applied to VCC1 and a super cap is

connected to VCC2 . Also assume that the trickle charger has been enabled with 1 diode and resister R1

between VCC1 and VCC2. The maximum current IMAX would,therefore,be calculated as follows:

IMAX = (5.0V - diode drop) / R1 » (5.0V - 0.7V) / 2kW » 2.2mA

As the super cap charges, the voltage drop between VCC1 and VCC2 will decrease and, therefore, the

charge current will decrease.

POWER CONTROL

Power is provided through the VCC1, VCC2, and VBAT pins. Three different power supply configurations

are illustrated in Figure 4. Configuration 1 shows the DS1305 being backed up by a non-rechargeable

energy source such as a lithium battery. In this configuration, the system power supply is connected to

VCC1 and VCC2 is grounded. The DS1305 will be write protected if VCC1 is less than VBAT. The DS1305

will be fully accessible when VCC1 is greater than VBAT + 0.2V.

Configuration 2 illustrates the DS1305 being backed up by a rechargeable energy source. In this case, the

VBAT pin is grounded, VCC1 is connected to the primary power supply, and VCC2 is connected to the

secondary supply (the rechargeable energy source). The DS1305 will operate from the larger of VCC1 or

VCC2. When VCC1 is greater than VCC2 + 0.2V (typical), VCC1 will power the DS1305. When VCC1 is less

than VCC2, VCC2 will power the DS1305. The DS1305 does not write protect itself in this configuration.

Configuration 3 shows the DS1305 in battery operate mode where the device is powered only by a single

battery. In this case, the VCC1 and VBAT pins are grounded and the battery is connected to the VCC2 pin.

Only these three configurations are allowed. Unused supply pins must be grounded.

A typical operating circuit is shown on page 11.

DS1305

10 of 22

POWER SUPPLY CONFIGURATIONS FOR THE DS1305 Figure 4

Configuration 1: Backup Supply is a Nonrechargeable Lithium Battery

Configuration 2: Backup Supply is a Rechargeable Battery or Super Capacitor

Configuration 3: Battery Operate Mode

VCCTP

DS1305

11 of 22

SERIAL INTERFACE

The DS1305 offers the flexibility to choose between two serial interface modes. The DS1305 can

communicate with the SPI interface or with a standard 3-wire interface. The interface method used is

determined by the SERMODE pin. When this pin is connected to VCC, SPI communication is selected.

When this pin is connected to ground, standard 3-wire communication is selected.

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 determines the clock polarity 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 Figure 5). There is one clock for

each bit transferred. Address and data bits are transferred in groups of eight.

TYPICAL OPERATING CIRCUIT

DS1305

12 of 22

SERIAL CLOCK AS A FUNCTION OF MICROCONTROLLER CLOCK

POLARITY (CPOL) Figure 5

CPHA bit polarity (if applicable) may need to be set accordingly.

CPOL is a bit that is set in the microcontroller’s Control Register.

SDO remains at High Z until 8 bits of data are ready to be shifted out during a read.

ADDRESS AND DATA BYTES

Address and data bytes are shifted MSB first into the serial data input (SDI) and out of the serial data

output (SDO). Any transfer requires the address of the byte to specify a write or read to either a RTC or

RAM location, followed by one or more bytes of data. Data is transferred out of the SDO for a read

operation and into the SDI for a write operation (see Figure 6 and 7).

SPI SINGLE-BYTE WRITE Figure 6

SPI SINGLE-BYTE READ Figure 7

*SCLK can be either polarity.

CPOL = 1

SCLK

Data latch (write)

Shift data out (read)

CPOL = 0

SCLK

Data latch (write)

Shift data out (read)

DS1305

13 of 22

The address byte is always the first byte entered after CE is driven high. The most significant bit (A7) of

this byte determines if a read or write will take place. If A7 is 0, one or more read cycles will occur. If A7

is 1, one or more write cycles will occur.

Data transfers can occur 1 byte at a time or in multiple-byte burst mode. After CE is driven high an

address is written to the DS1305. After the address, one or more data bytes can be written or read. For a

single-byte transfer 1 byte is read or written and then CE is driven low. For a multiple-byte transfer,

however, multiple bytes can be read or written to the DS1305 after the address has been written. Each

read or write cycle causes the RTC register or RAM address to automatically increment. Incrementing

continues until the device is disabled. When the RTC is selected, the address wraps to 00h after

incrementing to 1Fh (during a read) and wraps to 80h after incrementing to 9Fh (during a write). When

the RAM is selected, the address wraps to 20h after incrementing to 7Fh (during a read) and wraps to

A0h after incrementing to FFh (during a write).

SPI MULTIPLE-BYTE BURST TRANSFER Figure 8

3-WIRE INTERFACE

The 3-wire interface mode operates similarly to the SPI mode. However, in 3-wire mode there is one I/O

instead of separate data in and data out signals. The 3-wire interface consists of the I/O (SDI and SDO

pins tied together), CE, and SCLK pins. In 3-wire mode, each byte is shifted in LSB first unlike SPI mode

where each byte is shifted in MSB first.

As is the case with the SPI mode, an address byte is written to the device followed by a single data byte

or multiple data bytes. Figure 9 illustrates a read and write cycle. In 3-wire mode, data is input on the

rising edge of SCLK and output on the falling edge of SCLK.

DS1305

14 of 22

3-WIRE SINGLE-BYTE TRANSFER Figure 9

SINGLE BYTE READ

SINGLE BYTE WRITE

In burst mode, RST is kept high and additional SCLK cycles are sent until the end of the burst.

*I/O is SDI and SDO tied together.

RST

SCLK

RST

SCLK

WA0A1A2 A3A4R/C1

I/O*

D0 D1 D2 D3 D4 D5 D6 D7

I/O*

WA0A1A2 A3A4R/C1

DS1305

15 of 22

ABSOLUTE MAXIMUM RATINGS*

Voltage on Any Pin Relative to Ground -0.5V to +7.0V

Storage Temperature -55°C to +125°C

Soldering Temperature 260°C for 10 seconds

* This is a stress rating only and functional operation of the device at these or any other conditions above

those indicated in the operation sections of this specification is not implied. Exposure to absolute

maximum rating conditions for extended periods of time may affect reliability.

Range Temperature VCC

Commercial 0°C to +70°C 2.0V to 5.5V VCC1 or VCC2

Industrial -40°C to +85°C 2.0V to 5.5V VCC1 or VCC2

RECOMMENDED DC OPERATING CONDITIONS Over the operating range*

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Supply Voltage

VCC1, VCC2

VCC1,

VCC2

2.0 5.5 V 7

Logic 1 Input VIH 2.0 VCC + 0.3 V

VCC = 2.0V -0.3 +0.3Logic 0 Input VIL

VCC = 5V -0.3 +0.8

VBAT Battery Voltage VBAT 2.0 5.5 V

VCCIF Supply Voltage VCCIF 2.0 5.5 V 11

*Unless otherwise specified.

DS1305

16 of 22

DC ELECTRICAL CHARACTERISTICS Over the operating range*

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

Input Leakage ILI -100 +500 µA

Output Leakage ILO -1 1 µA

VCC = 2.0V 0.4Logic 0 Output IOL= 1.5mA

IOL = 4.0mA

VOL

VCC = 5V 0.4

VCCIF = 2.0V 1.6Logic 1 Output IOH = -0.4mA

IOH = -1.0mA

VOH

VCCIF = 5V 2.4

VCC1 = 2.0V 0.425VCC1 Active Supply Current ICC1A

VCC1 = 5V 1.28

mA 2,8

VCC1 = 2.0V 25.3VCC1 Timekeeping Current

(Osc on)

ICC1T

VCC1 = 5V 81

µA 1,8

VCC1 = 2.0V 25VCC1 Standby Current

(Osc off)

ICC1S

VCC1 = 5V 80

µA 6,8

VCC2 = 2.0V 0.4VCC2 Active Supply Current ICC2A

VCC2 = 5V 1.2

mA 2,9

VCC2 = 2.0V 0.3VCC2 Timekeeping Current

(Osc on)

ICC2T

VCC2 = 5V 1

µA 1,9

VCC2 = 2.0V 200VCC2 Standby Current

(Osc off)

ICC2S

VCC2 = 5V 200

µA 6,9

Battery Timekeeping Current IBAT VBAT = 3V 400 nA 10

Battery Standby Current IBATS VBAT = 3V 200 nA 10

VCC Trip Point VCCTP VBAT - 50 VBAT +

200

Trickle Charge Resistors R1

Trickle Charge Diode

Voltage Drop

VTD 0.7 V

*Unless otherwise specified.

CAPACITANCE (TA = 25°C)

PARAMETER SYMBOL CONDITION TYP MAX UNITS NOTES

Input Capacitance CI10 pF

Output Capacitance CO15 pF

Crystal Capacitance CX6pF

DS1305

17 of 22

3-WIRE AC ELECTRICAL CHARACTERISTICS Over the operating range*

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

VCC = 2.0V 200Data to CLK Setup tDC

VCC = 5V 50

ns 3,4

VCC = 2.0V 280CLK to Data Hold tCDH

VCC = 5V 70

ns 3,4

VCC = 2.0V 800CLK to Data Delay tCDD

VCC = 5V 200

ns 3,4,5

VCC = 2.0V 1000CLK Low Time tCL

VCC = 5V 250

ns 4

VCC = 2.0V 1000CLK High Time tCH

VCC = 5V 250

ns 4

VCC = 2.0V 0.6CLK Frequency tCLK

VCC = 5V DC 2.0

MHz 4

VCC = 2.0V 2000CLK Rise and Fall tR, tF

VCC = 5V 500

VCC = 2.0V 4CE to CLK Setup tCC

VCC = 5V 1

µs4

VCC = 2.0V 240CLK to CE Hold tCCH

VCC = 5V 60

ns 4

VCC = 2.0V 4CE Inactive Time tCWH

VCC = 5V 1

µs4

VCC = 2.0V 280CE to Output High Z tCDZ

VCC = 5V 70

ns 3,4

VCC = 2.0V 280SCLK to Output High Z tCCZ

VCC = 5V 70

ns 3,4

*Unless otherwise specified.

TIMING DIAGRAM: 3-WIRE READ DATA TRANSFER Figure 10

DS1305

18 of 22

TIMING DIAGRAM: 3-WIRE WRITE DATA TRANSFER Figure 11

SPI AC ELECTRICAL CHARACTERISTICS Over the operating range*

PARAMETER SYMBOL MIN TYP MAX UNITS NOTES

VCC = 2.0V 200Data to CLK Setup tDC

VCC = 5V 50

ns 5,6

VCC = 2.0V 280CLK to Data Hold tCDH

VCC = 5V 70

ns 5,6

VCC = 2.0V 800CLK to Data Delay tCDD

VCC = 5V 200

ns 5,6,7

VCC = 2.0V 1000CLK Low Time tCL

VCC = 5V 250

ns 6

VCC = 2.0V 1000CLK High Time tCH

VCC = 5V 250

ns 6

VCC = 2.0V 0.6CLK Frequency tCLK

VCC = 5V DC 2.0

MHz 6

VCC = 2.0V 2000CLK Rise and Fall tR, tF

VCC = 5V 500

VCC = 2.0V 4CE to CLK Setup tCC

VCC = 5V 1

µs6

VCC = 2.0V 240CLK to CE Hold tCCH

VCC = 5V 60

ns 6

VCC = 2.0V 4CE Inactive Time tCWH

VCC = 5V 1

µs6

VCC = 2.0V 280CE to Output High Z tCDZ

VCC = 5V 70

ns 5,6

*Unless otherwise specified.

DS1305

19 of 22

TIMING DIAGRAM: SPI READ DATA TRANSFER Figure 12

TIMING DIAGRAM: SPI WRITE DATA TRANSFER Figure 13

DS1305

20 of 22

NOTES:

1. ICC1T and ICC2T are specified with CE set to a logic 0 and EOSC bit = 0 (oscillator enabled).

2. ICC1A and ICC2A are specified with CE=VCC, SCLK=2MHz at VCC = 5V; SCLK = 500kHz

at VCC = 2.0V, VIL = 0V, VIH = VCC, and EOSC bit = 0 (oscillator enabled).

3. Measured at VIH = 2.0V or VIL = 0.8V and 10ms maximum rise and fall time.

4. Measured with 50pF load.

5. Measured at VOH = 2.4V or VOL = 0.4V.

6. ICC1S and ICC2S are specified with CE set to a logic 0. The EOSC bit must be set to logic 1 (oscillator

disabled).

7. VCC = VCC1 , when VCC1 > VCC2 + 0.2V (typical); VCC = VCC2, when VCC2 > VCC1.

8. VCC2 = 0V.

9. VCC1 = 0V.

10. VCC1 < VBAT.

11. VCCIF must be less than or equal to the largest of VCC1, VCC2, and VBAT .

DS1305

21 of 22

DS1305 16-PIN DIP (300-MIL)

PKG 16-PIN

DIM MIN MAX

A IN

0.740

18.80

0.780

19.81

B IN

0.240

6.10

0.260

6.60

C IN

0.120

3.05

0.140

3.56

D IN

0.300

7.62

0.325

8.26

E IN

0.015

0.38

0.040

1.02

F IN

0.120

3.05

0.140

3.56

G IN

0.090

2.29

0.110

2.79

H IN

0.320

8.13

0.370

9.40

J IN

0.008

0.20

0.012

0.30

K IN

0.015

0.38

0.021

0.53

DS1305

22 of 22

DS1305 20-PIN TSSOP

DIM MIN MAX

A MM -1.10

A1 MM 0.05 -

A2 MM 0.75 1.05

C MM 0.09 0.18

L MM 0.50 0.70

e1 MM 0.65 BSC

B MM 0.18 0.30

D MM 6.40 6.90

E MM 4.40 NOM

G MM 0.25 REF

H MM 6.25 6.55

phi 0° 8°