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ISL12023 Folha de dados(PDF) 9 Page - Intersil Corporation |
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ISL12023 Folha de dados(HTML) 9 Page - Intersil Corporation |
9 / 28 page 9 FN6682.2 June 24, 2009 IRQ (Interrupt Output) This 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. Once triggered, the output will stay low until the Alarm status register bit is reset or, if the auto reset function is used, a read is performed to the status register. FOUT (Frequency Output) This pin provides a clock signal which is related to the crystal frequency. The output frequency is user selectable and enabled via the I2C bus. It is an open drain 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 bi-directional 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 VDD = 2.7V to 5.5VDC. A 0.1µF capacitor is recommended on the VDD pin to ground. LVRST (Low Voltage Reset) This pin provides an interrupt signal output. This signal notifies a host processor that the VDD level has dropped below the pre-programmed level, normally 85% of nominal VDD. The brownout trip level is programmable via a control register. It is an open drain active low output. 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 the ISL12023 for up to 10 years. Another option is to use a super capacitor for applications where VDD is interrupted for up to a month. See the “Application Section” on page 24 for more information. Normal Mode (VDD) to Battery-Backup Mode (VBAT) To transition from the VDD to VBAT mode, both of the following conditions must be met: Condition 1: VDD < VBAT - VBATHYS where VBATHYS ≈ 50mV Condition 2: VDD < VTRIP where VTRIP ≈ 2.2V Battery-Backup Mode (VBAT) to Normal Mode (VDD) The ISL12023 device will switch from the VBAT to VDD mode when one of the following conditions occurs: Condition 1: VDD > VBAT + VBATHYS where VBATHYS ≈ 50mV Condition 2: VDD > VTRIP + VTRIPHYS where VTRIPHYS ≈ 30mV These power control situations are illustrated in Figures 11 and 12. The I2C bus is deactivated in battery-backup mode to reduce power consumption. Aside from this, all RTC functions are operational during battery-backup mode. Except for SCL and SDA, all the inputs and outputs of the ISL12023 are active during battery-backup mode unless disabled via the control register. FIGURE 11. BATTERY SWITCHOVER WHEN VBAT > VTRIP VTRIP VBAT VTRIP + VTRIPHYS BATTERY-BACKUP MODE VDD VTRIP 3.0V 2.2V VBAT - VBATHYS VBAT VBAT + VBATHYS BATTERY-BACKUP MODE VDD VTRIP 2.2V 1.8V FIGURE 12. BATTERY SWITCHOVER WHEN VBAT < VTRIP ISL12023 |
Nº de peça semelhante - ISL12023 |
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Descrição semelhante - ISL12023 |
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