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ISL22316 bảng dữ liệu(PDF) 10 Page - Intersil Corporation |
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ISL22316 bảng dữ liệu(HTML) 10 Page - Intersil Corporation |
10 / 15 page 10 FN6186.2 September 1, 2009 Pin Description Potentiometers Pins RH AND RL The high (RH) and low (RL) terminals of the ISL22316 are equivalent to the fixed terminals of a mechanical potentiometer. RH and RL are referenced to the relative position of the wiper and not the voltage potential on the terminals. With WR set to 127 decimal, the wiper will be closest to RH, and with the WR set to 0, the wiper is closest to RL. RW RW is the wiper terminal and is equivalent to the movable terminal of a mechanical potentiometer. The position of the wiper within the array is determined by the WR register. SHDN The SHDN pin forces the resistor to end-to-end open circuit condition on RH and shorts RW to RL. When SHDN is returned to logic high, the previous latch settings put RWi at the same resistance setting prior to shutdown. This pin is logically AND with the SHDN bit in the ACR register. The I2C interface is still available in shutdown mode and all registers are accessible. This pin must remain HIGH for normal operation. Bus Interface Pins SERIAL DATA INPUT/OUTPUT (SDA) The SDA is a bidirectional serial data input/output pin for I2C interface. It receives device address, operation code, wiper address and data from an I2C external master device at the rising edge of the serial clock SCL, and it shifts out data after each falling edge of the serial clock. SDA requires an external pull-up resistor, since it is an open drain input/output. SERIAL CLOCK (SCL) This input is the serial clock of the I2C serial interface. SCL requires an external pull-up resistor, since it is an open drain input. DEVICE ADDRESS (A1, A0) The address inputs are used to set the least significant 2 bits of the 7-bit I2C interface slave address. A match in the slave address serial data stream must match with the Address input pins in order to initiate communication with the ISL22316. A maximum of four ISL22316 devices may occupy the I2C serial bus. Principles of Operation The ISL22316 is an integrated circuit incorporating one DCP with its associated registers, non-volatile memory and an I2C serial interface providing direct communication between a host and the potentiometer and memory. The resistor array is comprised of individual resistors connected in series. At either end of the array and between each resistor is an electronic switch that transfers the potential at that point to the wiper. The electronic switches on the device operate in a “make before break” mode when the wiper changes tap positions. When the device is powered down, the last value stored in IVR will be maintained in the non-volatile memory. When power is restored, the contents of the IVR is recalled and loaded into the WR to set the wiper to the initial value. DCP Description The DCP is implemented with a combination of resistor elements and CMOS switches. The physical ends of each DCP are equivalent to the fixed terminals of a mechanical potentiometer (RH and RL pins). The RW pin of the DCP is connected to intermediate nodes, and is equivalent to the wiper terminal of a mechanical potentiometer. The position of the wiper terminal within the DCP is controlled by a 7-bit volatile Wiper Register (WR). When the WR of a DCP contains all zeroes (WR<6:0>: 00h), its wiper terminal (RW) is closest to its “Low” terminal (RL). When the WR register of a DCP contains all ones (WR<6:0>: 7Fh), its wiper terminal (RW) is closest to its “High” terminal (RH). As the value of the WR increases from all zeroes (0) to all ones (127 decimal), the wiper moves monotonically from the position closest to RL to the closest to RH. At the same time, the resistance between RW and RL increases monotonically, while the resistance between RH and RW decreases monotonically. While the ISL22316 is being powered up, the WR is reset to 40h (64 decimal), which locates RW roughly at the center between RL and RH. After the power supply voltage becomes large enough for reliable non-volatile memory reading, the WR will be reload with the value stored in a non-volatile Initial Value Register (IVR). The WR and IVR can be read or written to directly using the I2C serial interface as described in the following sections. Memory Description The ISL22316 contains one non-volatile 8-bit register, known as the Initial Value Register (IVR), and two volatile 8-bit registers, Wiper Register (WR) and Access Control Register (ACR). Table 1 shows the Memory map of the ISL22316. The RL RW RH FIGURE 15. DCP CONNECTION IN SHUTDOWN MODE ISL22316 |
Số phần tương tự - ISL22316 |
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Mô tả tương tự - ISL22316 |
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