Os motores de busca de Datasheet de Componentes eletrônicos |
|
ISL54205A Folha de dados(PDF) 9 Page - Intersil Corporation |
|
ISL54205A Folha de dados(HTML) 9 Page - Intersil Corporation |
9 / 14 page 9 FN6342.1 December 7, 2006 The USB switches are active (turned ON) whenever the VBUS voltage is ≥ to VDD + 0.8V. VBUS is internally pulled low, so when VBUS is floating, the USB switches are OFF. Note: Whenever the USB switches are ON the audio drivers of the CODEC need to be at AC or DC ground or floating to keep from interfering with the data transmission. ISL54205A Operation The discussion that follows will discuss using the ISL54205A in the typical application shown in the block diagram on page 8. LOGIC CONTROL The state of the ISL54205A device is determined by the voltage at the VBUS pin (pin 2) and the CTRL pin (pin 10). Refer to truth-table on page 2 of data sheet. The VBUS pin and CTRL pin are internally pulled low through 4MΩ resistors to ground and can be left floating. The CTRL control pin is only active when VBUS is logic “0”. Logic control voltage levels: VBUS = Logic “0” (Low) when VBUS ≤ VDD + 0.2V or Floating. VBUS = Logic “1” (High) when VBUS ≥ VDD + 0.8V CTRL = Logic “0” (Low) when ≤ 0.5V or floating. CTRL = Logic “1” (High) when ≥ 1.4V Audio Mode If the VBUS pin = Logic “0” and CTRL pin = Logic “1,” the part will be in the Audio mode. In Audio mode the L (left) and R (right) 3 Ω audio switches are ON and the D- and D+ 5Ω switches are OFF (high impedance). In a typical application, VDD will be in the range of 2.7V to 3.6V and will be connected to the battery or LDO of the MP3 player or cell phone. When a headphone is plugged into the common connector, nothing gets connected at the VBUS pin (it is floating) and as long as the CTRL = Logic “1,” the ISL54205A part remains in the audio mode and the audio drivers of the player can drive the headphones and play music. USB Mode If the VBUS pin = Logic “1” and CTRL pin = Logic “0” or Logic “1,” the part will go into USB mode. In USB mode, the D- and D+ 5 Ω switches are ON and the L and R 3Ω audio switches are OFF (high impedance). When a USB cable from a computer or USB hub is connected at the common connector, the voltage at the VBUS pin will be driven to be in the range of 4.4V to 5.25V. The ISL54205A part will go into the USB mode. In USB mode, the computer or USB hub transceiver and the MP3 player or cell phone USB transceiver are connected and digital data will be able to be transmitted back and forth. When the USB cable is disconnected, the ISL54205A automatically turns the D+ and D- switches OFF. Low Power Mode If the VBUS pin = Logic “0” and CTRL pin = Logic “0,” the part will be in the Low Power mode. In the Low Power mode, the audio switches and the USB switches are OFF (high impedance). In this state, the device draws typically 1nA of current. EXTERNAL VBUS SERIES RESISTOR The ISL54205A contains a clamp circuit between VBUS and VDD. Whenever the VBUS voltage is greater than the VDD voltage by more than 2.55V, current will flow through this clamp circuitry into the VDD power supply bus. During normal USB operation, VDD is in the range of 2.7V to 3.6V and VBUS is in the range of 4.4V to 5.25V. The clamp circuit is not active and no current will flow through the clamp into the VDD supply. In a USB application, the situation can exist where the VBUS voltage from the computer could be applied at the VBUS pin before the VDD voltage is up to its normal operating voltage range and current will flow through the clamp into the VDD power supply bus. This current could be quite high when VDD is OFF or at 0V and could potentially damage other components connected in the circuit. In the application circuit, a 22kΩ resistor has been put in series with the VBUS pin to limit the current to a safe level during this situation. It is recommended that a current limiting resistor in the range of 10kΩ to 50kΩ be connected in series with the VBUS pin. It will have minimal impact on the logic level at the VBUS pin during normal USB operation and protect the circuit during the time VBUS is present before VDD is up to its normal operating voltage. Note: No external resistor is required in applications where VBUS will not exceed VDD by more than 2.55V. POWER The power supply connected at VDD (pin 1) provides power to the ISL54205A part. Its voltage should be kept in the range of 2.7V to 3.6V when used in a USB/Audio application to ensure you get proper switching when the VBUS voltage is at its lower limit of 4.4V. ISL54205A |
Nº de peça semelhante - ISL54205A |
|
Descrição semelhante - ISL54205A |
|
|
Ligação URL |
Privacy Policy |
ALLDATASHEETPT.COM |
ALLDATASHEET é útil para você? [ DONATE ] |
Sobre Alldatasheet | Publicidade | Contato conosco | Privacy Policy | roca de Link | Lista de Fabricantes All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |