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參數(shù)資料
| 型號： | PCM1750 |
| 英文描述： | Dual CMOS 18-Bit Monolithic Audio ANALOG-TO-DIGITAL CONVERTER |
| 中文描述： | 雙通道CMOS 18位單片音頻模擬數(shù)字轉(zhuǎn)換器 |
| 文件頁數(shù)： | 9/18頁 |
| 文件大小： | 240K |
| 代理商： | PCM1750 |
9
PCM1750
the next rising edge of CLKIN, at the end of the test interval,
the comparator latch is strobed, providing a feedback logic
level which tells the second data latch if bit-2 should be kept
or rejected. This logic level is stored in the data latch and is
passed on to switch S2 via the NOR gate on the falling edge
of the pulse from SR2. This decision to keep or reject bit-2
moves the comparator input closer to a null condition,
namely, zero potential. This sequential process continues for
bit-3 through bit-18 and nulls the comparator inputs to
within a value limited by the total system noise and the
resolution/speed of the comparator.
Notice from the timing diagram in Figure 2 that the succes-
sive approximation algorithm operates synchronously with
an external clock to minimize digitally-coupled switching
noise from corrupting either the sample-to-hold operation or
the critical comparator bit decisions. The two serial output
data streams are derived synchronously from the respective
latched comparator outputs and are available after a delay of
one CLKIN cycle as illustrated in Figure 2. The serial output
driver cells are TTL and CMOS compatible.
DIFFERENTIAL LINEARITY CALIBRATION
To understand the calibration of the PCM1750 it is neces-
sary to discuss some of the characteristics of poly-poly
capacitors. Poly capacitors are known to have equal or better
stability and matching properties when compared to other
precision components such as thin film resistors. On a well
controlled process, ratio matching is typically 0.1%—a
very respectable number for an untrimmed component. Even
more impressive is their ratio tracking versus temperature of
approximately 0.1ppm/
°
C.
Achieving DLE (differential linearity error) of less than 1/2
LSB at the 16-bit level requires ratio matching of the more
significant bits to about 0.001%. Since the untrimmed ratio
matching of poly capacitors is about two orders of magni-
tude larger than this requirement, a one-time factory calibra-
tion of the upper bits is required as described in the next
section. Next, consider the effect of temperature due to the
ratio tracking of 0.lppm/
°
C. Over a 50
°
C span, DLE will
change less than 1LSB at 18-bits; therefore, recalibration at
temperature extremes is not necessary. Because of this
excellent stability versus temperature (and versus time, also),
the one-time factory calibration to correct initial DLE is
more than satisfactory in meeting the accuracy requirements
of the PCM1750.
TDAC OPERATION
Operation of the TDAC (trim DAC), which is laser trimmed
at the wafer level, is described using bit-1 as an example.
Switch S1T (see Figure 1) operates between two voltage
levels—a reference level set by voltage divider Ra, Rb and
a laser trimmable level set by R1a, R1b. The differences of
these two levels is coupled by capacitor C1T to the minus
input of the comparator to generate a correction voltage for
D
Q
L R
D
Q
R
SR
2
D
Q
L R
D
Q
L R
D
Q
R
SR
18
D
Q
L R
D
Q
L R
D
Q
S
SR
1
D
Q
L R
D
Q
R
SR
19
Control
Logic
To MSB
Switches Left
To Bit 2
Switches Left
To Bit 18
Switches Left
To MSB
Switches Right
To Bit 2
Switches Right
To Bit 18
Switches Right
Serial Data
From Latching
Comparator
Serial Data
From Latching
Comparator
Data
Latches
Left Channel
19-Bit
Shift
Register
Data
Latches
Right Channel
FIGURE 4. PCM1750 Successive Approximation Logic Diagram.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| PCM1750P | Dual CMOS 18-Bit Monolithic Audio ANALOG-TO-DIGITAL CONVERTER |
| PCM1750U | Dual CMOS 18-Bit Monolithic Audio ANALOG-TO-DIGITAL CONVERTER |
| PCM1753DBQR | 24-BIT, 192 kHz SAMPLING ENHANCED MULTI-LEVEL, DELTA-SIGMA, AUDIO DIGITAL-TO-ANALOG CONVERTER |
| PCM1755DBQR | 24-BIT, 192 kHz SAMPLING ENHANCED MULTI-LEVEL, DELTA-SIGMA, AUDIO DIGITAL-TO-ANALOG CONVERTER |
| PCM1753 | 24-BIT, 192 kHz SAMPLING ENHANCED MULTI-LEVEL, DELTA-SIGMA, AUDIO DIGITAL-TO-ANALOG CONVERTER |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| PCM1750P | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| PCM1750P/PCM1750U | 制造商:BB 制造商全稱:BB 功能描述:PCM1750P. PCM1750U - Dual CMOS 18-Bit Monolithic Audio ANALOG-TO-DIGITAL CONVERTER |
| PCM1750U | 功能描述:音頻模/數(shù)轉(zhuǎn)換器 IC Dual CMOS 18-Bit Mono A/D Converter RoHS:否 制造商:Wolfson Microelectronics 轉(zhuǎn)換速率: 分辨率: ADC 輸入端數(shù)量: 工作電源電壓: 最大工作溫度: 最小工作溫度: 安裝風(fēng)格: 封裝 / 箱體: 封裝: |
| PCM1750U/1K | 功能描述:音頻模/數(shù)轉(zhuǎn)換器 IC Dual CMOS 18-Bit Mono A/D Converter RoHS:否 制造商:Wolfson Microelectronics 轉(zhuǎn)換速率: 分辨率: ADC 輸入端數(shù)量: 工作電源電壓: 最大工作溫度: 最小工作溫度: 安裝風(fēng)格: 封裝 / 箱體: 封裝: |
| PCM1750U/1KG4 | 功能描述:音頻模/數(shù)轉(zhuǎn)換器 IC Dual CMOS 18-Bit Mono A/D Converter RoHS:否 制造商:Wolfson Microelectronics 轉(zhuǎn)換速率: 分辨率: ADC 輸入端數(shù)量: 工作電源電壓: 最大工作溫度: 最小工作溫度: 安裝風(fēng)格: 封裝 / 箱體: 封裝: |
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