參數(shù)資料
型號(hào)： TDA8757
廠商： NXP Semiconductors N.V.
英文描述： Triple 8-bit ADC 170 Msps
中文描述： 三路8位ADC為170 MSPS
文件頁(yè)數(shù)： 13/37頁(yè)
文件大?。?/td> 895K
代理商： TDA8757
Philips Semiconductors
TDA8757
Triple 8-bit ADC 170 Msps
Preliminary data
Rev. 07 — 28 February 2002
13 of 37
9397 750 09457
Koninklijke Philips Electronics N.V. 2002. All rights reserved.
8.2.1
Variable gain amplifiers
Three independent variable gain amplifiers are used to provide a full-scale input
signal to the 8-bit ADC for each channel. The gain adjustment range is designed so
that for an input range varying from 0.4 to 1.2 V (p-p), the output signal corresponds
to the ADC full-scale input of 1 V (p-p).
To ensure that the gain does not vary over the whole operating temperature range, a
reference voltage V
ref
= 2.5 V (DC) with a maximum variation of 100 ppm/
°
C, is
supplied externally on pin VREF.
The calibration of the gains is done using the following principle: On the incoming of a
pulse supplied to pin HSYNC, an internal multiplexer switches from the RGB video
signals to a reference voltage (
1
16
V
ref
). The ADCs inputs become this reference
signal and the three corresponding outputs are compared to pre-set values loaded in
three 7-bit registers: COARSER, COARSEG and COARSEB. Depending on the
result of the comparisons, the three gains are adjusted such that the ADC outputs
become equal to the pre-set values in the registers. The three gains are simply
controlled by changing the values in the COARSE registers.
The signal supplied on pin HSYNC, may be selected active HIGH or active LOW. The
choice is done through the serial interface by setting bit ‘Hlevel’ in the control register
(active HIGH when bit Hlevel = 0).
This active part of the signal has to occur during the blanking period of the signal in
order not to interrupt the active video. Normally the horizontal synchronization signal,
provided by the video source, is connected to pin HSYNC.
The values loaded in the gain registers (COARSER, COARSEG, COARSEB) are
chosen among 68 values (see
Table 6
).
A fine correction is also used to finely tune the gain on the three channels and to
compensate the channel-to-channel gain mismatch. The fine correction is done using
the following principle: the three binary codes, stored in the three 5-bit registers
(FINER, FINEG and FINEB) are converted into three analog voltages (with three
DACs) and are independently added to the reference voltage (
1
16
V
ref
). Thus, three
different reference voltages are used for the gain calibration of the three channels.
When the COARSE registers are set at full-scale, the resolution of the fine registers
corresponds to
1
2
LSB peak-to-peak (see
Equation 3
).
8.2.2
Important recommendations
The clamping and the gain calibration requires two external signals (pulses). One
signal is connected to pin CLP and the other is connected to pin HSYNC. It is very
important that:
The active part of these two signals occur during the blanking of the video signal,
in order not to interrupt or disturb the active video.
The active part of these two signals does not overlap on each other, in order to
perform correctly the gain calibration and the clamping. Normally the clamp pulse
is sent after the end of the horizontal synchronization pulse.
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TDA8757HL 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Triple 8-bit ADC 170 Msps
TDA8758 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:YC 8-bit low-power analog-to-digital video interface
TDA8758G 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:YC 8-bit low-power analog-to-digital video interface
TDA8759HV/8/C1 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 3X8-BITS VIDEO ADC 110MSPS RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
TDA8759HV/8/C1,551 功能描述:模數(shù)轉(zhuǎn)換器 - ADC 3X8-BITS VIDEO RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
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