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PCM69AU 参数 Datasheet PDF下载

PCM69AU图片预览
型号: PCM69AU
PDF下载: 下载PDF文件 查看货源
内容描述: 先进的1位的BiCMOS双路18位数字 - 模拟转换器 [Advanced 1-Bit BiCMOS Dual 18-Bit DIGITAL-TO-ANALOG CONVERTER]
分类和应用: 转换器
文件页数/大小: 13 页 / 97 K
品牌: BB [ BURR-BROWN CORPORATION ]
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DISCUSSION OF  
SPECIFICATIONS  
VOUT = 1.2mA • RNF  
The PCM67 and PCM69A are specified to provide critical  
performance criteria for a variety of applications. The accu-  
racy of a D/A converter is described by the transfer function  
shown in Figure 1.  
VOUT  
VCOM  
RNF  
1.2mA  
IOUT  
Digital In  
+FSR  
VOUT  
011...11  
VCOM  
Gain Error  
(3.5V)  
FIGURE 2. I/V Amplifier Circuit.  
000...00  
S/N RATIO  
Analog  
Out  
111...11  
S/Nratioisdefinedastheratiooffullscaleoutputandnoinput  
noise level at BPZ point. The PCM67/69A is specified at  
110dB typical with “IHF-A” filter.  
BPZ  
BPZ – 1LSB  
100...00  
–FSR  
LEVEL LINEARITY ERROR  
(VCOM = 3.5V)  
Level linearity error is defined as the deviation of actual  
analog output level from digital input level. PCM67/69A is  
specified at 1dB typical at –90dB output level. The 0.5LSB  
quantization error at –90dB of 16-bit conversion is equal to  
+1.94dB, –2.5dB.  
FIGURE 1. Transfer Performance.  
DIGITAL INPUT CODE  
The PCM67/69A accepts Binary Two’s Complement (BTC)  
digital input code (MSB FIRST).The relationship of digital  
input to analog output is shown in Table 1.  
TOTAL HARMONIC DISTORTION  
THD is a key parameter in audio applications, THD is a  
measure of the magnitude and distribution of the linearity  
error, differential linearity error, and noise, as well as quanti-  
zation error. To be useful, THD should be specified for both  
highlevelandlowlevelinputsignals.Thiserrorisunadjustable  
and is the most meaningful indicator of D/A converter accu-  
racy for audio applications.  
ANALOG OUTPUT  
(VOLTAGE)  
ANALOG OUTPUT  
(CURRENT)  
DIGITAL INPUT  
7FFFFF (HEX)  
00003F (HEX)  
FFFFFF (HEX)  
80003F (HEX)  
+FSR  
BPZ  
BPZ – 1LSB  
–FSR  
–1.2mA  
–0.6mA  
–0.59995mA  
0mA  
THD is defined as the ratio of the square root of the sum of the  
squares of the values of the harmonics to the value of the  
fundamental input frequency and is expressed in percent or  
dB. The rms value of the PCM67/69A error referred to the  
input can be shown to be  
TABLE I. Digital Code and Analog Out.  
GAIN ERROR AND GAIN MISMATCH,  
CHANNEL-TO-CHANNEL  
Gain error is defined as deviation of the output current span  
from the ideal span of 1.2mA (FSR) on each channel. Gain  
error of PCM67/69A is typically ±3% of FSR.  
n
2
1
n
(1)  
ε rms  
=
EL (i) + EQ(i)  
i = 1  
Gain mismatch, channel-to-channel is defined as the differ-  
ence in gain error between the left channel and right channel.  
where n is the number of samples in one cycle of any given  
sine wave, EL(i) is the linearity error of the PCM67 or  
PCM69A at each sampling point. THD can then be expressed  
as  
THE RELATIONSHIP OF VCOM AND I/V OUT  
The output current range of PCM67 and PCM69A is 0mA to  
1.2mA as shown in Table 1.  
n
2
In the typical application, the non-inverting input of the  
external I/V op amp is connected to the VCOM pin of PCM67  
and PCM69A. Accordingly, the output voltage level at FSR  
after I/V conversion is VCOM voltage (+3.5V) as shown in  
Figure 2.  
1
n
EL (i) + EQ (i)  
εrms  
i =1  
THD =  
=
× 100%  
E
Erms  
rms  
(2)  
where Erms is the rms signal-voltage level.  
®
PCM67/69A  
6