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ISL22444UFV20Z 数据表(PDF) 11 Page - Intersil Corporation |
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ISL22444UFV20Z 数据表(HTML) 11 Page - Intersil Corporation |
11 / 19 page 11 FN6426.0 May 24, 2007 Pin Description Potentiometer Pins RHI AND RLI The high (RHi) and low (RLi) terminals of the ISL22444 are equivalent to the fixed terminals of a mechanical potentiometer. RHi and RLi are referenced to the relative position of the wiper and not the voltage potential on the terminals. With WRi set to 255 decimal, the wiper will be closest to RHi, and with the WRi set to 0, the wiper is closest to RLi. RWI RWi 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 WRi register. Bus Interface Pins SERIAL CLOCK (SCK) This is the serial clock input of the SPI serial interface. SERIAL DATA OUTPUT (SDO) The SDO is a serial data output pin. During a read cycle, the data bits are shifted out on the falling edge of the serial clock SCK and will be available to the master on the following rising edge of SCK. The output type is configured through ACR[1] bit for Push- Pull or Open Drain operation. Default setting for this pin is Push-Pull. An external pull up resistor is required for Open Drain output operation. Note: the external pull up voltage not allowed beyond VCC. SERIAL DATA INPUT (SDI) The SDI is the serial data input pin for the SPI interface. It receives device address, operation code, wiper address and data from the SPI remote host device. The data bits are shifted in at the rising edge of the serial clock SCK, while the CS input is low. CHIP SELECT (CS) CS LOW enables the ISL22444, placing it in the active power mode. A HIGH to LOW transition on CS is required prior to the start of any operation after power up. When CS is HIGH, the ISL22444 is deselected and the SDO pin is at high impedance, and (unless an internal write cycle is underway) the device will be in the standby state. Principles of Operation The ISL22444 is an integrated circuit incorporating four DCPs with their associated registers, non-volatile memory and the SPI serial interface providing direct communication between host, potentiometers and memory. The resistor arrays are comprised of individual resistors connected in a 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 IVRi will be maintained in the non-volatile memory. When power is restored, the content of the IVRi is recalled and loaded into the corresponding WRi to set the wiper to the initial position. DCP Description Each 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 (RHi and RLi pins). The RWi 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 an 8-bit volatile Wiper Register (WRi). When the WRi of a DCP FIGURE 13. MIDSCALE GLITCH, CODE 7Fh TO 80h FIGURE 14. LARGE SIGNAL SETTLING TIME Typical Performance Curves (Continued) SCL WIPER CS WIPER UNLOADED, MOVEMENT FROM 0h to FFh ISL22444 |
类似零件编号 - ISL22444UFV20Z |
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类似说明 - ISL22444UFV20Z |
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