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FSA805 — USB2.0 High-Speed (480Mbps), UART, and
Audio Switch with Negative Signal Capability
Features
Description
3:1 Switch Handles:
Negative-Swing-Capable Audio Channel
The FSA805 is a 3:1 USB accessory switch that enables
USB data, stereo/mono audio, and UART data to share
a common connector port. It is designed for high-speed
USB 2.0 signaling. The architecture is designed to allow
audio signals to swing below ground (to -0.8V) so a
common USB and headphone jack can be used for
personal media players and portable peripheral devices.
Built-in Termination Resistors for Audio Pop
Reduction
The FSA805 meets both USB Rev. 2.0 and micro-USB
specifications.
Simple Switch Control Using Two Select Pins
Audio Headsets
UART
Up to 2 High-Full and Low-Speed USB Data
Applications
Cell Phones, MP3 Players, PDAs
Ordering Information
Part Number
Operating
Temperature Range
Top Mark
FSA805UMX
-40 to +85°C
JZ
Eco Status
Green
Package
12-Lead Quad, UMLP, 1.8x1.8mm
For Fairchild’s definition of Eco Status, please visit: http://www.fairchildsemi.com/company/green/rohs_green.html.
VCC
FSA805
R_HOST
L_HOST
R
RxD_HOST
TxD_HOST
3:1
MUX
and
Charge
Pump
DP_HOST
DM_HOST
SEL[0]
SEL[1]
DP_CON
DM_CON
GND
Switch
Control
Figure 1. Functional Block Diagram
© 2009 Fairchild Semiconductor Corporation
FSA805 • Rev. 1.0.0
www.fairchildsemi.com
FSA805 — USB2.0 High-Speed (480Mbps), UART, and Audio Switch with Negative Signal Capability
July 2013
FSA805 — USB2.0 High-Speed (480Mbps), UART, and Audio Switch with Negative Signal Capability
Application Diagram
Baseband
Processor
Audio
Codec
VCC
R_HOST
RxD_HOST
DM_HOST
UART or
HS USB
Micro
USB
L_HOST
TxD_HOST
UART or
HS USB
FSA805
R
3:1
MUX
and
Charge
Pump
VBUS
DM_CON
DP_CON
ID
DP_HOST
GND
SEL[0]
Switch
Control
SEL[1]
Figure 2. Typical Application
© 2009 Fairchild Semiconductor Corporation
FSA805 • Rev. 1.0.0
www.fairchildsemi.com
2
The FSA805 USB2.0 accessory switch is designed to
consolidate wired accessories for portable devices, such
as cellular telephones and portable audio players. The
benefits of consolidation include reduced space
requirements from a reduction of connectors and their
size. The micro-USB connector, for example, reduces
connector height and depth, allowing for slimmer overall
designs. Using the USB industry standard and a
common connector type for devices such as chargers
and headsets, greatly reduces the waste associated with
new phone purchases by allowing re-use of the devices.
Applications with Multiple USB Controllers
The FSA805 UART port (RxD_HOST, TxD_HOST) can
be used as a High-speed USB interface. This allows it to
operate in an application with two USB controllers (one
full speed, and the other full or high speed).
In this configuration, it is recommended to configure the
switches to OPEN before switching to the other (second)
USB interface. The OPEN setting duration should be
long enough for the accessory to go to a SE0 state, so
when the switch is set to the other (second) USB port,
the new controller re-enumerates.
Using just five wires for all connection types
considerably reduces the cost of wired accessories and
simplifies their construction. The FSA805 facilitates
adopting this methodology because it is designed to
redirect the DP/DM pins from the USB connector to one
of three ports at the baseband’s discretion.
Table 1.
Mode Descriptions
The FSA805 has two select pins to control the switching
operations, SEL[0], and SEL[1]. Table 1 describes mode
operation.
Selection Truth Table
SEL[1]
SEL[0]
Switch Action
Description
0
0
OPEN
Open all switch paths (device in low-power mode)(1)
0
1
USB, UART
Closes USB/UART1 path to D+/D-, default condition
- DP_CON connected to RxD_HOST
- DM_CON connected to TxD_HOST
1
0
USB, UART
Closes USB/UART2 path to D+/D- DP_CON connected to DP_HOST
- DM_CON connected to DM_HOST
1
1
AUDIO
(2)
Closes audio path to D+/D- only
- DP_CON connected to R_HOST
- DM_CON connected to L_HOST
Notes:
1. When the audio switch is in the OPEN position (Table 1, line1), the R and L are terminated to GND with internal
termination resistors to discharge any stray capacitance that could cause audio pop.
2. The SELECT pins are CMOS inputs and should not be left in a floating condition. Some applications require the
UART path be in the CLOSED position on power-up for initial programming of the device under test. If that
condition is desired, the two SELECT pins should be pulled to the correct levels with external resistors that
should exceed 100K to reduce the static power consumption. In other applications, adding weak pull-down
resistors to GND defaults the device to all paths open (low-power mode).
© 2009 Fairchild Semiconductor Corporation
FSA805 • Rev. 1.0.0
www.fairchildsemi.com
3
FSA805 — USB2.0 High-Speed (480Mbps), UART, and Audio Switch with Negative Signal Capability
Functional Description
GND
DM_CON
DP_CON
SEL[1]
12 11 10
9
VCC
2
7
R_HOST
3
4
5
6
RxD_HOST
L_HOST
TxD_HOST
8
DM_HOST
1
DP_HOST
SEL[0]
Figure 3. 12-Pin, UMLP Pin Assignments (Top-Through View)
Pin Descriptions
Name
Pin #
Description
USB Interface
DP_HOST
3
DM_HOST
4
D+ signal, dedicated USB port to be connected to the resident USB transceiver on the phone.
Can also be used for UART signaling.
D- signal, dedicated USB port to be connected to the resident USB transceiver on the phone.
Can also be used for UART signaling.
Audio Interface
R_HOST
7
Right audio channel from phone audio-out codec
L_HOST
8
Left audio channel from phone audio-out codec
5
Tx connection from resident UART transceiver on the phone. Can also be used for HS USB
signaling.
6
Rx connection from resident UART transceiver on the phone. Can also be used for HS USB
signaling.
2
Input voltage supply pin to be connected to the phone battery output
UART Interface
TxD_HOST
RxD_HOST
Power Interface
VCC
Connector Interface
GND
DP_CON
DM_CON
9
Ground
11
Connected to the USB connector D+ pin; depending on the signaling mode, this pin can share
D+, R, Rxd, or MIC signals
10
Connected to the USB connector D- pin; depending on the signaling mode, this pin can share
D-, L, or Txd signals
Switch Control
SEL[1:0]
1,12
Switch selection pins; refer to Table 1 for truth table
© 2009 Fairchild Semiconductor Corporation
FSA805 • Rev. 1.0.0
www.fairchildsemi.com
4
FSA805 — USB2.0 High-Speed (480Mbps), UART, and Audio Switch with Negative Signal Capability
Pin Configuration
Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be
operable above the recommended operating conditions and stressing the parts to these levels is not recommended.
In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability.
The absolute maximum ratings are stress ratings only.
Symbol
VCC
VSW
Parameter
Switch I/O Voltage
Input Clamp Diode Current
ISW
Switch I/O Current (Continuous)
TSTG
Max.
Unit
-0.5
6.0
V
USB
-1.0
VCC +0.5
Stereo/Mono Audio Path Active
-1.5
VCC +0.5
All Other Channels
-0.5
VCC +0.5
Supply Voltage from Battery / Baseband
IIK
ISWPEAK
Min.
-50
Peak Switch Current (Pulsed at 1ms
Duration,
