Datenblatt-Suchmaschine für elektronische Bauteile |
|
ISL54211IRTZ-T Datenblatt(PDF) 11 Page - Intersil Corporation |
|
ISL54211IRTZ-T Datenblatt(HTML) 11 Page - Intersil Corporation |
11 / 19 page 11 FN6662.1 August 25, 2008 CTRL = Logic “0” (Low) when ≤ 0.5V or Floating. CTRL = Logic “1” (High) when ≥ 1.4V Audio Mode If the IN 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) 2.5 Ω audio switches are ON, the D- and D+ 5.5Ω switches are OFF (high impedance) and the audio click and pop circuitry is OFF (high impedance). When nothing is plugged into the common connector or a headphone 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 ISL54211 low. As long as the CTRL = Logic “1”, the ISL54211 part remains in the audio mode and the audio drivers of the player can drive the headphones and play music. 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 D- and D+ 5.5 Ω switches are ON and the L and R 2.5Ω audio 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 presence of the 5V VBUS voltage and drive the IN pin voltage high. The ISL54211 part will go into the USB mode. In USB mode the computer or USB hub transceiver and the MP3 player or cellphone USB transceiver are connected and digital data will be able to be transmit 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 or Mute mode. Mute Mode If the IN pin = Logic “0” and CTRL pin = Logic “0”, the part will be in the Mute mode. In the Mute mode, the audio switches and the USB switches are OFF (high impedance) and the audio click and pop circuitry is ON. Before powering down or powering up of the audio CODECs drivers, the ISL54211 should be put in the Mute mode. In Mute mode, transients present at the L and R signal pins due to the changing DC voltage of the audio drivers will not pass to the headphones, preventing clicks and pops in the headphones. Before power-up and power-down of the ISL54211, part the IN and CTRL control pins should be driven to ground or tri-stated. This will put the switch in the mute state, which turns all switches OFF and activates the click and pop circuitry. This will minimize transients at the speaker loads during power-up and power-down. See Figure 30 in the “Typical Performance Curves” on page 17. AC-COUPLED CLICK AND POP OPERATION Single supply audio drivers have their signal biased at a DC offset voltage, usually at 1/2 the DC supply voltage of the driver. As this DC bias voltage comes up or goes down during power-up or power-down of the driver, a transient can be coupled into the speaker load through the DC blocking capacitor (see “Typical Application Block Diagrams” on page 9). When a driver is OFF and suddenly turned ON, the rapidly changing DC bias voltage at the output of the driver will cause an equal voltage at the input side of the switch due to the fact that the voltage across the blocking capacitor cannot change instantly. If the switch is in the Audio mode or there is no low impedance path to discharge the blocking capacitor voltage at the input of the switch, before turning on the audio switch, a transient discharge will occur in the speaker, generating a click/pop noise. Proper elimination of a click/pop transient at the speaker loads while powering up or down of the audio drivers requires that the ISL54211 have its click/pop circuitry activated by putting the part in the Mute mode. This allows the transients generated by the audio drivers to be discharged through the click and pop shunt circuitry. Once the driver DC bias has reached VDD/2 and the transient on the switch side of the DC blocking capacitor has been discharged to ground through the click/pop shunt circuitry, the audio switches can be turned ON and connected through to the speaker loads without generating any undesirable click/pop noise in the speakers. With a typical DC blocking capacitor of 220µF and the click/pop shunt circuitry designed to have a resistance of 20 Ω to 70Ω, allowing a 100ms wait time to discharge the transient before placing the switch in the Audio mode will prevent the transient from getting through to the speaker load. See Figures 28 and 29 in the “Typical Performance Curves” page 16. USING THE COMPUTER VBUS VOLTAGE TO DRIVE THE “IN” PIN Rather than using a micro-processor to control the IN logic pin, one can directly drive the IN pin using the VBUS voltage from the computer or USB hub. See the “Typical Application Block Diagrams” on page 9. When a headphone or nothing is connected at the common connector, the internal 4M Ω pull-down will pull the IN pin low, putting the ISL54211 in the Audio or Mute 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 ISL54211 |
Ähnliche Teilenummer - ISL54211IRTZ-T |
|
Ähnliche Beschreibung - ISL54211IRTZ-T |
|
|
Link URL |
Privatsphäre und Datenschutz |
ALLDATASHEETDE.COM |
War ALLDATASHEET hilfreich? [ DONATE ] |
Über Alldatasheet | Werbung | Kontakt | Privatsphäre und Datenschutz | Linktausch | Hersteller 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 |