- 您现在的位置：买卖IC网 > PDF目录98263 > TLV990-21PFBG4 (TEXAS INSTRUMENTS INC) SPECIALTY CONSUMER CIRCUIT, PQFP48 PDF资料下载
参数资料
| 型号： | TLV990-21PFBG4 |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 消费家电 |
| 英文描述： | SPECIALTY CONSUMER CIRCUIT, PQFP48 |
| 封装： | GREEN, PLASTIC, TQFP-48 |
| 文件页数： | 8/23页 |
| 文件大小： | 408K |
| 代理商： | TLV990-21PFBG4 |
TLV99021
3V, 10BIT, 21MSPS AREA CCD ANALOG FRONT END
SLAS299A AUGUST 2000 REVISED MARCH 2004
16
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
PRINCIPLES OF OPERATION
CDS and PGA
The output from the CCD sensor is first fed to a correlated double sampler (CDS) through the CCDIN pin. The
CCD signal is sampled and held during the reset-reference interval and the video-signal interval. By subtracting
two resulting voltage levels, the CDS removes low-frequency noise from the output of the CCD sensor and
obtains the voltage difference between the CCD reference level and the video level of each pixel. Two
sample/hold control pulses (SR and SV) are required to perform the CDS function.
The CCD output is capacitively coupled to the TLV990-21. The ac-coupling capacitor is clamped to establish
proper dc bias during the dummy pixel interval by the CLCCD input. The bias at the input to the TLV990-21 is
set to 1.2 V. Normally, CLCCD is applied at the sensor’s line rate. A capacitor, with a value ten times larger than
that of the input ac-coupling capacitor, should be connected between the CLREF pin and AGND.
When operating the TLV990-21 at its maximum speed, the CCD internal source resistance should be smaller
than 50
. Otherwise CCD output buffering is required.
The signal is sent to the PGA after the CDS function is complete. The PGA gain can be adjusted from 0 to 36 dB
by programming the internal-gain register via the serial port. The PGA is digitally controlled with 10-bit resolution
on a linear dB scale, resulting in a 0.045-dB gain step. The gain can be expressed by the following equation,
Gain = PGA code
× 0.045 dB
Where PGA code has a range of 0 to 767.
ADC
The ADC employs a pipelined architecture to achieve high throughput and low-power consumption. Fully-
differential implementation and digital-error correction ensure 10-bit resolution.
The latency of the ADC data output is 6 ADCCLK cycles, as shown in Figure 1. Pulling the OE pin (pin 24) high
puts the ADC output in high impedance.
user DACs
The TLV990-21 includes two user DACs that can be used for external analog settings. The output voltage of
each DAC can be independently set and has a range of 0 V up to the supply voltage, with an 8-bit resolution.
When the user DACs are not used in a camera system, they can be put in the standby mode by programming
control bits in the control register.
internal timing
The SR and SV signals are required to operate the CDS, as previously explained. The user needs to
synchronize the SR and SV clocks with the CCD signal waveform. The output of the ADC is read out to external
circuitry by the ADCCLK signal, which is also used internally to control both ADC and PGA operations. The
positive-half cycle of the ADCCLK signal is required to always fall in between two adjacent SV pulses as shown
in Fig. 1. The user can then fine tune the ADCCLK timing in relation to the CDS timing to achieve optimal
performance.
The CLCCD signal is used to activate the input clamping and the OBCLP signal is used to activate auto-optical
black and offset correction.
相关PDF资料 |
PDF描述 |
|---|---|
| TLV990-28PFB | SPECIALTY CONSUMER CIRCUIT, PQFP48 |
| TLV990-28PFBG4 | SPECIALTY CONSUMER CIRCUIT, PQFP48 |
| TLV990-40PFB | SPECIALTY CONSUMER CIRCUIT, PQFP48 |
| TLV990-40PFBG4 | SPECIALTY CONSUMER CIRCUIT, PQFP48 |
| TLV990APFB | SPECIALTY CONSUMER CIRCUIT, PQFP48 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| TLV990-28 | 制造商:Texas Instruments 功能描述:CCD Analogue Front End 28MSPS TLV990-28 |
| TLV99028PFB | 制造商:Texas Instruments 功能描述: |
| TLV990-28PFB | 功能描述:视频模拟/数字化转换器集成电路 3-V 10-Bit 28-MSPS Area CCD RoHS:否 制造商:Texas Instruments 输入信号类型:Differential 转换器数量:1 ADC 输入端数量:4 转换速率:3 Gbps 分辨率:8 bit 结构: 输入电压:3.3 V 接口类型:SPI 信噪比: 电压参考: 电源电压-最大:3.45 V 电源电压-最小:3.15 V 最大功率耗散: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:TCSP-48 封装:Reel |
| TLV990-28PFBG4 | 功能描述:视频模拟/数字化转换器集成电路 3-V 10-Bit 28-MSPS Area CCD RoHS:否 制造商:Texas Instruments 输入信号类型:Differential 转换器数量:1 ADC 输入端数量:4 转换速率:3 Gbps 分辨率:8 bit 结构: 输入电压:3.3 V 接口类型:SPI 信噪比: 电压参考: 电源电压-最大:3.45 V 电源电压-最小:3.15 V 最大功率耗散: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:TCSP-48 封装:Reel |
| TLV990-40 | 制造商:Texas Instruments 功能描述:CCD Analogue Front End 40MSPS TLV990-40 |
发布紧急采购，3分钟左右您将得到回复。