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ISL54208IRZ データシート(PDF) 10 Page - Intersil Corporation |
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ISL54208IRZ データシート(HTML) 10 Page - Intersil Corporation |
10 / 15 page 10 FN6410.0 December 18, 2006 ISL54208 Operation The discussion that follows will discuss using the ISL54208 in the typical application shown in the block diagrams on page 8. VDD SUPPLY The dc power supply connected at VDD (pin 1) provides the required bias voltage for proper switch operation. The part can operate with a supply voltage in the range of 1.8V to 5.5V. In a typical USB/Audio/Video application for portable battery powered devices the VDD voltage will come from a battery or an LDO and be in the range of 2.7V to 3.6V. For best possible USB full-speed operation (12Mbps) it is recommended that the VDD voltage be ≥3.3V in order to get a USB data signal level above 2.5V. LOGIC CONTROL The state of the ISL54208 device is determined by the voltage at the IN pin (pin 2) and the CTRL pin (pin 10). Refer to truth-table on page 2 of data sheet. These logic pins are 1.8V compatible with VDD in the range of 2.7V to 3.6V and can be controlled by a standard μprocessor. The CTRL pin is internally pulled low through a 4MΩ resistors to ground and can be left floating or tri-stated by the μprocessor. The CTRL control pin is only active when IN is logic “0”. The IN pin does not have an internal pull-down resistor and must not be allowed to float. It must be driven High or Low. The voltage at the IN pin can exceed the VDD voltage by as much as 2.55V. This allows the VBUS voltage from a computer or USB hub (4.4V to 5.25V) to drive the IN pin while the VDD voltage is in the range of 2.7V to 3.6V. An external pull-down resistor is required from the IN pin to ground when directly driving the IN pin with the computer VBUS voltage. See the section titled “USING THE COMPUTER VBUS VOLTAGE TO DRIVE THE “IN’ PIN”. Logic control voltage levels: IN = Logic “0” (Low) when ≤0.5V IN = Logic “1” (High) when IN ≥1.4V CTRL = Logic “0” (Low) when ≤0.5V or floating. CTRL = Logic “1” (High) when ≥1.4V Audio/Video Mode If the IN pin = Logic “0” and CTRL pin = Logic “1,” the part will be in the Audio/Video mode. In Audio/Video mode the NC1 and NC2 3 Ω audio/video switches are ON and the NO1 and NO2 5 Ω USB switches are OFF (high impedance). When nothing is plugged into the common connector or a audio/video jack is plugged into the common connector, the μprocessor will sense that there is no voltage at the VBUS pin of the connector and will drive and hold the IN control pin of the ISL54208 low. As long as the CTRL = Logic “1,” the ISL54208 part will be in the audio/video mode and the media player audio and video drivers can drive the speaker and video display. USB Mode If the IN pin = Logic “1” and CTRL pin = Logic “0” or Logic “1” the part will go into USB mode. In USB mode, the NO1 and NO2 5 Ω switches are ON and the NC1 and NC2 3Ω audio/video switches are OFF (high impedance). When a USB cable from a computer or USB hub is connected at the common connector, the μprocessor will sense the present of the 5V VBUS and drive the IN pin voltage high. The ISL54208 part will go into the USB mode. In USB mode, the computer or USB hub transceiver and the media player USB transceiver are connected and digital data will be able to be transmitted back and forth. When the USB cable is disconnected, the μprocessor will sense that the 5V VBUS voltage is no longer connected and will drive the IN pin low and put the part back into the Audio/Video or Low Power Mode. Low Power Mode If the IN pin = Logic “0” and CTRL pin = Logic “0,” the part will be in the Low Power mode. In the Low Power mode, the NCx switches and the NOx switches are OFF (high impedance). In this state, the device draws typically 1nA of current. USING THE COMPUTER VBUS VOLTAGE TO DRIVE THE “IN” PIN External IN Pull-Down Resistor Rather than using a micro-processor to control the IN logic pin you can directly drive the IN pin using the VBUS voltage from the computer or USB hub. In order to do this you must connected an external pull-down resistor from the IN pin to ground. When an audio/video jack or nothing is connected at the common connector the external pull-down resistor will pull the IN pin low putting the ISL54208 in the Audio/Video Mode or Low Power Mode depending on the condition of the CTRL pin. When a USB cable is connected at the common connector the voltage at the IN pin will be driven to 5V and the part will automatically go into the USB mode. When the USB cable is disconnected from the common connector the voltage at the IN pin will be pulled low by the pull-down resistor and return to the Audio/Video Mode or Low Power Mode depending on the condition of the CTRL pin. Note: The voltage at the IN pin can exceed the VDD voltage by as much as 2.55V. This allows the VBUS voltage from a computer or USB hub (4.4V to 5.25V) to drive the IN pin while the VDD voltage is in the range of 2.7V to 3.6V. ISL54208 |
同様の部品番号 - ISL54208IRZ |
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同様の説明 - ISL54208IRZ |
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