Texas Instruments SRC4382 Evaluation Module (EVM) and USB motherboard SRC4382EVM-PDK SRC4382EVM-PDK 데이터 시트
제품 코드
SRC4382EVM-PDK
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R1 and R2 are selected to achieve the desired output voltage level while maintaining the required 75
transmitter output impedance.
W
The TX+ output impedance is negligible.
(a) Transformer-Coupled Unbalanced Output
1:1
R2
0.1 F
m
TX+
Digital Output
75
Unbalan
W
ced
(RCA or BNC connector)
R1
(b) Unbalanced Output Without Transformer
R2
0.1
m
F
TX+
Digital Output
75
Unbalan
W
ced
(RCA or BNC connector)
R1
(1) Toshiba TOTX141, TOTX173, TOTX176, TOTX179, or equivalent.
SN74AVC1T45
or Equivalent
If VIO < +3.0V.
VIO
5
+3.3V
6
3
1
2
4
All-Plastic Fiber
(5 or 10 meters maximum)
AESOUT
Optical
Transmitter
(1)
SBFS030C – JANUARY 2006 – REVISED SEPTEMBER 2007
Figure 89. Unbalanced Line Output Interfaces
Optical interfaces utilizing all-plastic fiber are commonly employed for consumer audio equipment where
interconnections are less than 10m in length. Most optical transmitter modules utilized for a digital audio interface
operate from a single +3.3V or +5V supply and have a TTL-compatible logic input. The CMOS buffered
transmitter output of the SRC4382, AESOUT (pin 34), is capable of driving the optical transmitter with VIO supply
voltages down to +3.0V. If the VIO supply voltage is less than +3.0V, then level translation logic is required to
drive the optical transmitter input. A good choice for this application is the Texas Instruments SN74AVC1T45
single bus transceiver. This device features two power-supply rails, one for the input side and one for the output
side. For this application, the input side supply is powered from the VIO supply, while the output side is powered
from a +3.3V supply. This will boost the logic high level to a voltage suitable for driving the TTL compatible input
configuration.
interconnections are less than 10m in length. Most optical transmitter modules utilized for a digital audio interface
operate from a single +3.3V or +5V supply and have a TTL-compatible logic input. The CMOS buffered
transmitter output of the SRC4382, AESOUT (pin 34), is capable of driving the optical transmitter with VIO supply
voltages down to +3.0V. If the VIO supply voltage is less than +3.0V, then level translation logic is required to
drive the optical transmitter input. A good choice for this application is the Texas Instruments SN74AVC1T45
single bus transceiver. This device features two power-supply rails, one for the input side and one for the output
side. For this application, the input side supply is powered from the VIO supply, while the output side is powered
from a +3.3V supply. This will boost the logic high level to a voltage suitable for driving the TTL compatible input
configuration.
shows the recommended optical transmitter interface circuits.
Figure 90. Interfacing to an Optical Transmitter Module
The AESOUT output may also be used to drive external logic or line driver devices directly.
illustrates
the recommended logic interface techniques, including connections with and without level translation.
illustrates an external line driver interface utilizing the Texas Instruments SN75ALS191 dual differential line
driver. If the VIO supply of the SRC4382 is set from +3.0V to +3.3V, no logic level translation is required between
the AESOUT output and the line driver input. If the VIO supply voltage is below this range, then the optional logic
level translation logic of
driver. If the VIO supply of the SRC4382 is set from +3.0V to +3.3V, no logic level translation is required between
the AESOUT output and the line driver input. If the VIO supply voltage is below this range, then the optional logic
level translation logic of
is required. The SN75ALS191 dual line driver is especially useful in
applications where simultaneous 75
Ω
and 110
Ω
line interfaces are required.
46
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