ISL54207 Datasheet, PDF (9/14 Pages) Intersil Corporation – Low Voltage, Dual SPDT, USB/CVBS/ Audio Switches, with Negative Signal Capability

ISL54207
FIGURE 8. VECTOR-SCOPE PLOT BEFORE SWITCH
FIGURE 9. VECTOR-SCOPE PLOT AFTER SWITCH
Figure 18 shows the differential gain (DG) and differential
phase (DP) plots at the output of the switch using an actual
NTSC composite video signal and a VM700A Video
Measurement Test Set. DG = 0.28% and DP = 0.04°.
These NC switches are uni-directional switches. The
audio/video sources should be connected at the NC side of
the switch (pins 7 and 8) and the speaker load and video
receiver should be connected at the COM side of the switch
(pins 3 and 4).
The NC switches are active (turned ON) whenever the V_BUS
voltage is ≤ to V_DD + 0.2V or floating and the CTRL voltage ≥
to 1.4V.
Note: Whenever the NC switches are ON the USB
transceivers need to be in the high impedance state or static
high or low state.
NO1 and NO2 USB Switches
The two NO (normally open) USB switches (NO1, NO2) are
5Ω bidirectional switches that are designed to pass
high-speed USB differential 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 Figure 14 for High-speed Eye
Pattern taken with switch in the signal path.
The maximum signal range for the USB switches is from
-1.5V to V_DD. The signal voltage at NO1 and NO2 should
not be allowed to exceed the V_DD voltage rail or go below
ground by more than -1.5V.
The NO switches are active (turned ON) whenever the V_BUS
voltage is ≥ to V_DD + 0.8V. VBUS is internally pulled low, so
when VBUS is floating, the USB switches are OFF.
Note: Whenever the NO switches are ON, the audio and
video drivers need to be at AC or DC ground or floating to
keep from interfering with the data transmission.
ISL54207 Operation
The discussion that follows will discuss using the ISL54207 in
the typical application shown in the block diagram on page 8.
LOGIC CONTROL
The state of the ISL54207 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 the 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 ≤ V_DD + 0.2V or
Floating.
VBUS = Logic “1” (High) when VBUS ≥ V_DD + 0.8V
CTRL = Logic “0” (Low) when ≤ 0.5V or floating.
CTRL = Logic “1” (High) when ≥ 1.4V
Audio/Video Mode
If the VBUS 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 3Ω audio/video switches are ON and the
NO1 and NO2 5Ω USB switches are OFF (high impedance).
In a typical application, V_DD will be in the range of 2.7V to
3.6V and will be connected to the battery or LDO of the
media player. When a audio/video jack 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
ISL54207 part remains in the audio/video mode and the
media player audio and video drivers can drive the speaker
and video display.
9
FN6403.0
December 5, 2006