DS1308 Datasheet, PDF(4/16 Page) Dallas Semiconductor

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DS1308

Low-Current I2C RTC with 56-Byte NV RAM

POWER-UP/DOWN CHARACTERISTICS

(TA = -40NC to +85NC, unless otherwise noted.) (Notes 2, 16)

PARAMETER

SYMBOL

MIN

Recovery at Power-Up

VCC Slew Rate (VPF to 0V)

VCC Slew Rate (0V to VPF)

tREC

tVCCF

tVCCR

TYP

MAX

UNITS

1/50

V/Fs

1/1

V/Fs

CAPACITANCE

(TA = +25NC, unless otherwise noted.) (Note 16)

PARAMETER

SYMBOL

MIN

TYP

MAX

Input Capacitance

I/O Capacitance

Warning: Negative undershoots below -0.3V while the part is in battery-backed mode may cause loss of data.

UNITS

Note 2: Limits are 100% production tested at TA = +25NC and TA = +85NC. Limits over the operating temperature range and

relevant supply voltage are guaranteed by design and characterization. Typical values are not guaranteed.

Note 3: SCL clocking at max frequency. VSCL = 0V to VCC.

Note 4: Specified with I2C bus inactive. Timekeeping and square-wave functions operational.

Note 5: CH = ECLK = SQWE = 0.

Note 6: CH = ECLK = 0, SQWE = RS1 = RS0 = 1, IOUT = 0mA.

Note 7: CH = 1. ECLK = SQWE = 0.

Note 8: The minimum SCL clock frequency is limited by the bus timeout feature, which resets the serial bus interface if SCL is

held low for tTIMEOUT.

Note 9: After this period, the first clock pulse is generated.

Note 10: A device must internally provide a hold time of at least 300ns for the SDA signal (referenced to the VIHMIN of the SCL

signal) to bridge the undefined region of the falling edge of SCL.

Note 11: The maximum tHD:DAT has only to be met if the device does not stretch the low period (tLOW) of the SCL signal.

Note 12: A fast-mode device can be used in a standard-mode system, but the requirement tSU:DAT R to 250ns must then be met.

This is automatically the case if the device does not stretch the low period of the SCL signal. If such a device does stretch

the low period of the SCL signal, it must output the next data bit to the SDA line tRMAX + tSU:DAT = 1000 + 250 = 1250ns

before the SCL line is released.

Note 13: CB is the total capacitance of one bus line, including all connected devices, in pF.

Note 14: The parameter tOSF is the period of time the oscillator must be stopped for the OSF flag to be set over the voltage range

of 2.4V P VCC P VCCMAX.

Note 15: The DS1308 can detect any single SCL clock held low longer than tTIMEOUTMIN. The deviceâs I2C interface is in reset

state and can receive a new START condition when SCL is held low for at least tTIMEOUTMAX. Once the part detects this

condition the SDA output is released. The oscillator must be running for this function to work.

Note 16: Guaranteed by design and not 100% production tested.

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