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ISL54217 датащи(PDF) 10 Page - Intersil Corporation |
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ISL54217 датащи(HTML) 10 Page - Intersil Corporation |
10 / 21 page 10 FN6817.3 May 4, 2009 to combine the stereo audio and USB data channels into a single shared connector, thereby saving space and component cost. The Typical application block diagram of this functionality is previously shown. The ISL54217 contains two logic control pins (C1 and C0) that determine the state of the device. The part has the following five states or modes of operation: All SWITCHES OFF; USB1; USB2; Audio; and Audio Mute. These states are discussed in detail in “Logic Control” on page 10. A detailed description of the various types of switches are provided in “Audio Switches” beginning on page 10. Audio Switches The two audio switches (L, R) are 2.3 Ω switches that can pass signals that swing below ground. Over a signal range of ±1V (0.707Vrms) with VDD > 2.7V, these switches have an extremely low rON resistance variation. They can pass ground referenced audio signals with very low distortion (<0.05% THD+N) when delivering 15.6mW into a 32 Ω headphone speaker load. See Figures 20, 21, 22, 23 and 24 THD+N performance curves. Crosstalk between the L and R audio switches over the frequency range of 20Hz to 20kHz when driving a 32 Ω load is < -88dB. These switches have excellent off-isolation > 105dB over the audio band when connected to 32 Ω loads and 77dB when connected to 20k Ω loads (In Audio Mute mode). See Figures 25 and 26 in “Typical Performance Curves” section beginning on page 12. The audio drivers should be connected at the L and R side of the switch (pins 2 and 3) and the speaker loads should be connected at the COM side of the switch (pins 7 and 8). The switches have click and pop circuitry on the L and R side that is activated when the part comes out of Audio mode by taking the C1 and C0 logic pins low (All OFF mode). The ISL54217 should be put in this mode before powering down or powering up of the audio CODEC drivers. In this mode the audio, USB1, USB2 switches will be OPEN (OFF) and the audio click and pop circuitry will be ON. The high off-isolation of the audio switches along with the click and pop circuitry will isolate the transients generated during power-up and power down of the audio CODECs from getting through to the headphones thus eliminating click and pop noise in the headphones. See the “AC Coupled click and pop operation” on page 12. The audio switches are active (turned ON) whenever the C1 and C0 logic pins are logic “1” (High). USB Switches The four USB switches (1D+, 1D-, 2D+, 2D-) are 6.2 Ω bidirectional switches that were specifically designed to pass high-speed USB differential data signals in the range of 0V to 400mV. The switches have low capacitance and high bandwidth to pass USB high-speed signals (480Mbps) with minimum edge and phase distortion to meet USB 2.0 signal quality specifications. See Figures 27 and 28 for High-speed Eye Pattern taken with switch in the signal path. These switches can also swing rail to rail and pass USB full-speed signals (12Mbps) with minimal distortion. See Figure 29 for Full-speed Eye Pattern taken with switch in the signal path. The maximum normal operating signal range for the USB switches is from -1V to VDD. The signal voltage at D- and D+ should not be allow to exceed the VDD voltage rail or go below ground by more than -1V for normal operation. However in the event that the USB 5.25V VBUS voltage were shorted to one or both of the COM pins, the ISL54217 has fault protection circuitry to prevent damage to the ISL54217 part. The fault circuitry allows the signal pins (COM-, COM+, 1D-, 1D+, 2D-, 2D+, L and R) to be driven up to 5.25V while the VDD supply voltage is in the range of 0V to 4.6V. This fault condition causes no stress to the IC. In addition, when VDD is at 0V (ground) all switches are OFF and the fault voltage is isolated from the other side of the switch. When VDD is in the range of 2.7V to 4.6V the fault voltage will pass through to the output of an active switch channel. Note: During the fault condition normal operation is not guaranteed until the fault condition is removed. The USB (1D+ and 1D-) switches are active (turned ON) whenever the C1 is logic “0” (Low) and C0 is logic “1” (High). The USB (2D+ and 2D-) switches are active (turned ON) whenever the C1 is logic “1” (High) and C0 is logic “0” (Low) provided the last state was not the Audio or Audio Mute state. ISL54217 Operation The discussion that follows will discuss using the ISL54217 in the “Block Diagram” on page 9. LOGIC CONTROL The state of the ISL54217 device is determined by the voltage at the C1 pin (pin 9) and the C0 pin (pin 10). The part has five states or modes of operation. The All SWITCHES OFF mode, USB1 mode, USB2 mode, Audio mode and Audio Mute mode. Refer to “Truth Table” on page 3 and “State Diagram” on page 2 of data sheet. The C1 pin and C0 pin are internally pulled low through 4MΩ resistors to ground and can be tri-stated or left floating. The C1 pin and C0 pin can be driven with a voltage that is higher than the VDD supply voltage. They can be driven up to 5.25V with the VDD supply in the range of 2.7V to 4.6V. Driving the logic higher than the supply rail will cause the logic current to increase. With VDD = 2.7V and VLOGIC = 5.25V, ILOGIC current is approximately 5.5µA. ISL54217 |
Аналогичный номер детали - ISL54217 |
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Аналогичное описание - ISL54217 |
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