參數(shù)資料
型號(hào): PCM1740E
英文描述: Stereo Audio DIGITAL-TO-ANALOG CONVERTER with VCXO and PLL
中文描述: 立體聲音頻數(shù)模轉(zhuǎn)換器與石英振蕩器和PLL
文件頁數(shù): 8/20頁
文件大?。?/td> 359K
代理商: PCM1740E
8
PCM1740
The 27MHz clock is available at the MCKO output (pin 5).
The VCXO output frequency can be precisely tuned using a
control voltage at the XTUN input (pin 3). The tuning range
is 27MHz
±
150ppm typical for a 0V to +3V control voltage
range. Figure 3 shows the VCXO equivalent circuit, while
Figure 4 shows the typical tuning curve.
At power up, the VCXO requires 5ms start up time. The
VCXO also exhibits a 10
μ
s settling time in response to
changes in the XTUN control voltage. VCXO operation and
the MCKO output are not effected by the power on or
external reset functions, continuing to operate during the
initialization sequence.
Crystal Selection
The VCXO connects to an external 27MHz crystal via XT1
(pin 1) and XT2 (pin 24). The crystal should be AT-cut,
fundamental mode with
±
30ppm accuracy and less than 50
motional resistance. Crystal shunt capacitance should be 3pF
maximum, while load capacitance should be less than 7pF.
Miniature lead type or surface-mount devices are recom-
mended. External load capacitors are not needed, since they
are provided on-chip. The crystal should be placed as close as
possible to the XT1 and XT2 pins to reduce effects of parasitic
capacitance and land resistance.
PROGRAMMABLE PHASE LOCKED LOOP (PLL)
The PCM1740 includes an on-chip PLL for generating a 256f
S
or 384f
S
audio system clock from the 27MHz VCXO output.
A block diagram of the PLL section is shown in Figure 5. The
PLL output clock is used by the digital filter and delta-sigma
modulator circuitry, and is made available at the SCKO output
(pin 21) for use with additional audio converters and signal
processors.
Tuning Voltage (V)
V
27.005
27.004
27.003
27.002
27.001
27.000
26.999
26.998
26.997
26.996
26.995
0.0
0.5
1.5
1.0
2.0
2.5
3.0
3.5
4.0
27MHz
Crystal
XTUN
0V to +3V
VCXO
MCKO
27MHz
±
150ppm
SCKO
256/384f
S
Frequency
Selection
ROM
Phase
Detector
and
Loop Filter
PLL
N Counter
Frequency Selection
Control Register 3
VCO
M Counter
FIGURE 3. VCXO Equivalent Circuit.
FIGURE 4. VCXO Output Frequency (MCKO) versus
Tuning Voltage (XTUN).
XT1
27MHz
Crystal
27MHz
Tuned Clock
Voltage
Range
0 to 3V
1
24
3
XTUN
C
LV
XT2
C
L
FIGURE 5. PLL Block Diagram.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
PCM1740E/2K 功能描述:音頻數(shù)/模轉(zhuǎn)換器 IC Stereo DAC w/Prog PLL&VCXO RoHS:否 制造商:Texas Instruments 轉(zhuǎn)換器數(shù)量: 分辨率:16 bit 接口類型:I2S, UBS 轉(zhuǎn)換速率: 信噪比:98 dB 工作電源電壓:5 V DAC 輸出端數(shù)量:2 工作溫度范圍:- 25 C to + 85 C 電源電流:23 mA 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-32 封裝:Reel
PCM1740E/2KG4 功能描述:音頻數(shù)/模轉(zhuǎn)換器 IC Stereo DAC w/Prog PLL&VCXO RoHS:否 制造商:Texas Instruments 轉(zhuǎn)換器數(shù)量: 分辨率:16 bit 接口類型:I2S, UBS 轉(zhuǎn)換速率: 信噪比:98 dB 工作電源電壓:5 V DAC 輸出端數(shù)量:2 工作溫度范圍:- 25 C to + 85 C 電源電流:23 mA 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-32 封裝:Reel
PCM1740E-1/2K 制造商:Texas Instruments 功能描述:
PCM1740EG4 功能描述:音頻數(shù)/模轉(zhuǎn)換器 IC Stereo DAC w/Prog PLL&VCXO RoHS:否 制造商:Texas Instruments 轉(zhuǎn)換器數(shù)量: 分辨率:16 bit 接口類型:I2S, UBS 轉(zhuǎn)換速率: 信噪比:98 dB 工作電源電壓:5 V DAC 輸出端數(shù)量:2 工作溫度范圍:- 25 C to + 85 C 電源電流:23 mA 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-32 封裝:Reel
PCM1741 制造商:BB 制造商全稱:BB 功能描述:+3.3V Single-Supply, 24-Bit, 96kHz Sampling Enhanced Multilevel, Delta-Sigma, Audio DIGITAL-TO-ANALOG CONVERTER