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ISL1208IU8Z-TK データシート(PDF) 7 Page - Intersil Corporation |
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ISL1208IU8Z-TK データシート(HTML) 7 Page - Intersil Corporation |
7 / 21 page 7 FN8085.5 August 23, 2006 General Description The ISL1208 device is a low power real time clock with timing and crystal compensation, clock/calendar, power fail indicator, periodic or polled alarm, intelligent battery backup switching, and battery-backed user SRAM. The oscillator uses an external, low-cost 32.768kHz crystal. The real time clock tracks time with separate registers for hours, minutes, and seconds. The device has calendar registers for date, month, year and day of the week. The calendar is accurate through 2099, with automatic leap year correction. The ISL1208's powerful alarm can be set to any clock/calendar value for a match. For example, every minute, every Tuesday or at 5:23 AM on March 21. The alarm status is available by checking the Status Register, or the device can be configured to provide a hardware interrupt via the IRQ pin. There is a repeat mode for the alarm allowing a periodic interrupt every minute, every hour, every day, etc. The device also offers a backup power input pin. This VBAT pin allows the device to be backed up by battery or SuperCap with automatic switchover from VDD to VBAT. The entire ISL1208 device is fully operational from 2.0V to 5.5V and the clock/calendar portion of the device remains fully operational down to 1.8V (Standby Mode). Pin Description X1, X2 The X1 and X2 pins are the input and output, respectively, of an inverting amplifier. An external 32.768kHz quartz crystal is used with the ISL1208 to supply a timebase for the real time clock. Internal compensation circuitry provides high accuracy over the operating temperature range from -40°C to +85°C. This oscillator compensation network can be used to calibrate the crystal timing accuracy over temperature either during manufacturing or with an external temperature sensor and microcontroller for active compensation. The device can also be driven directly from a 32.768kHz source at pin X1. VBAT This input provides a backup supply voltage to the device. VBAT supplies power to the device in the event that the VDD supply fails. This pin can be connected to a battery, a Super Cap or tied to ground if not used. IRQ/FOUT (Interrupt Output/Frequency Output) This dual function pin can be used as an interrupt or frequency output pin. The IRQ/FOUT mode is selected via the frequency out control bits of the control/status register. • Interrupt Mode. The pin provides an interrupt signal output. This signal notifies a host processor that an alarm has occurred and requests action. It is an open drain active low output. • Frequency Output Mode. The pin outputs a clock signal which is related to the crystal frequency. The frequency output is user selectable and enabled via the I2C bus. It is an open drain active low output. Serial Clock (SCL) The SCL input is used to clock all serial data into and out of the device. The input buffer on this pin is always active (not gated). It is disabled when the backup power supply on the VBAT pin is activated to minimize power consumption. Serial Data (SDA) SDA is a bidirectional pin used to transfer data into and out of the device. It has an open drain output and may be ORed with other open drain or open collector outputs. The input buffer is always active (not gated) in normal mode. An open drain output requires the use of a pull-up resistor. The output circuitry controls the fall time of the output signal with the use of a slope controlled pull-down. The circuit is designed for 400kHz I2C interface speeds. It is disabled when the backup power supply on the VBAT pin is activated. VDD, GND Chip power supply and ground pins. The device will operate with a power supply from 2.0V to 5.5VDC. A 0.1µF capacitor is recommended on the VDD pin to ground. Functional Description Power Control Operation The power control circuit accepts a VDD and a VBAT input. Many types of batteries can be used with Intersil RTC products. For example, 3.0V or 3.6V Lithium batteries are appropriate, and battery sizes are available that can power FIGURE 7. STANDARD OUTPUT LOAD FOR TESTING THE DEVICE WITH VDD = 5.0V SDA AND IRQ/FOUT 1533 Ω 100pF 5.0V FOR VOL= 0.4V AND IOL = 3mA EQUIVALENT AC OUTPUT LOAD CIRCUIT FOR VDD = 5V FIGURE 8. RECOMMENDED CRYSTAL CONNECTION X1 X2 ISL1208 |
同様の部品番号 - ISL1208IU8Z-TK |
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同様の説明 - ISL1208IU8Z-TK |
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