參數(shù)資料
型號: TCM320AC37PT
廠商: Texas Instruments, Inc.
英文描述: VOICE-BAND AUDIO PROCESSORS VBAPE
中文描述: 語音頻帶音頻處理器VBAPE
文件頁數(shù): 15/23頁
文件大小: 317K
代理商: TCM320AC37PT
TCM320AC36, TCM320AC37
VOICE-BAND AUDIO PROCESSORS (VBAP
)
SLWS003C – MAY 1992 – REVISED APRIL – 1998
15
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
PRINCIPLES OF OPERATION
conversion laws
The TCM320AC36 provides
μ
-law companding operation that approximates the CCITT G.711
recommendation. The TCM320AC37 provides A-law companding operation that approximates the CCITT
G.711 recommendation. The linear mode of operation uses a 13-bit two’s-complement format and is the same
for both the TCM320AC36 and the TCM320AC37.
transmit operation
microphone input
The microphone input amplifier is designed specifically to interface to electret-type microphone elements, as
shown in Figure 5. The VMID buffer circuit provides a voltage (MICBIAS) equal to 1/2 V
CC
as a reference for
the microphone amplifier and a bias voltage to the electret microphone. The microphone amplifier output
(MICGS) is used in conjunction with a feedback network and applied to the amplifier inverting input (MICIN) to
set the amplifier gain. In the companded mode, when the MICIN signal level decreases to a level near the noise
floor, the VBAP mutes the signal and outputs zero bits while continuing to monitor the signal level. When the
input level once again exceeds the noise threshold, the mute is released and normal operation resumes. Input
hysteresis is provided to ensure noiseless transitions into and out of the muted condition. VMID appears at a
terminal to provide a place to filter the VMID voltage.
TCM320AC36/37 VBAP
2 k
17
VMID
18
MICIN
19
MICGS
20
MICBIAS
To Transmit Filters
Microphone Amplifier
VMID Buffer
10 k
+
VMID Reference
For Amplifiers
1
μ
F
VMID
Generator
Electret
Microphone
+
3.3
μ
F
+
MICMUTE
6
10 k
+
VDD
470 pF
NOTE A: Terminal numbers shown are for the DW and N packages.
Figure 5. Typical Microphone Interface
microphone mute function
The MICMUTE input causes the digital circuitry to transmit all zero code on DOUT.
transmit filter
A low-pass antialiasing section is included on the device and achieves a 35-dB attenuation at the sampling
frequency. No external components are required to provide the necessary antialiasing function for the
switched-capacitor section of the transmit filter.
相關PDF資料
PDF描述
TCM320AC54 MONOLITHIC SERIAL INTERFACE COMBINED PCM CODEC AND FILTER
TCM320AC54DW MONOLITHIC SERIAL INTERFACE COMBINED PCM CODEC AND FILTER
TCM320AC54N MONOLITHIC SERIAL INTERFACE COMBINED PCM CODEC AND FILTER
TCM809(中文) 3-Pin Microcontroller Reset Monitors(3引腳微控制器復位監(jiān)控器)
TCM810(中文) 3-Pin Microcontroller Reset Monitors(3引腳微控制器復位監(jiān)控器)
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