link to page 4 DS1307 64 x 8, Serial, I2C Real-Time Clock OSCILLATOR CIRCUIT The DS1307 uses an external 32.768kHz crystal. The oscillator circuit does not require any external resistors or capacitors to operate. Table 1 specifies several crystal parameters for the external crystal. Figure 1 shows a functional schematic of the oscillator circuit. If using a crystal with the specified characteristics, the startup time is usually less than one second. 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. Refer to Application Note 58: Crystal Considerations with Dallas Real-Time Clocks for detailed information. Table 1. Crystal Specifications*PARAMETERSYMBOLMINTYPMAXUNITS Nominal Frequency fO 32.768 kHz Series Resistance ESR 45 kΩ Load Capacitance CL 12.5 pF *The crystal, traces, and crystal input pins should be isolated from RF generating signals. Refer to Application Note 58: Crystal Considerations for Dallas Real-Time Clocks for additional specifications. Figure 2. Recommended Layout for Crystal LOCAL GROUND PLANE (LAYER 2) X1 CRYSTAL X2 GND NOTE: AVOID ROUTING SIGNAL LINES IN THE CROSSHATCHED AREA (UPPER LEFT QUADRANT) OF THE PACKAGE UNLESS THERE IS A GROUND PLANE BETWEEN THE SIGNAL LINE AND THE DEVICE PACKAGE. RTC AND RAM ADDRESS MAP Table 2 shows the address map for the DS1307 RTC and RAM registers. The RTC registers are located in address locations 00h to 07h. The RAM registers are located in address locations 08h to 3Fh. During a multibyte access, when the address pointer reaches 3Fh, the end of RAM space, it wraps around to location 00h, the beginning of the clock space. 7 of 14 Document Outline TYPICAL OPERATING CIRCUIT PIN CONFIGURATIONS ORDERING INFORMATION ABSOLUTE MAXIMUM RATINGS RECOMMENDED DC OPERATING CONDITIONS (TA = 0 C to +70 C, TA = -40 C to +85 C.) (Notes 1, 2) DC ELECTRICAL CHARACTERISTICS (VCC = 4.5V to 5.5V; TA = 0 C to +70 C, TA = -40 C to +85 C.) (Notes 1, 2) DC ELECTRICAL CHARACTERISTICS (VCC = 0V, VBAT = 3.0V; TA = 0 C to +70 C, TA = -40 C to +85 C.) (Notes 1, 2) AC ELECTRICAL CHARACTERISTICS (VCC = 4.5V to 5.5V; TA = 0 C to +70 C, TA = -40 C to +85 C.) CAPACITANCE (TA = +25 C) 64 x 8, Serial, I2C Real-Time Clock SYMBOL TIMING DIAGRAM CLOCK ACCURACY RTC AND RAM ADDRESS MAP CLOCK AND CALENDAR CONTROL REGISTER I2C DATA BUS RS1
Купить DS1307+ на РадиоЛоцман.Цены — от 5.39 до 688 ₽
