Moteur de recherche de fiches techniques de composants électroniques |
|
VSP2230 Fiches technique(PDF) 6 Page - Burr-Brown (TI) |
|
|
VSP2230 Fiches technique(HTML) 6 Page - Burr-Brown (TI) |
6 / 18 page VSP2230 SLAS319 – MAY 2001 6 www.ti.com programmable gain amplifier (PGA) (continued) –10 0 10 20 30 40 50 0 100 200 300 400 500 600 700 800 900 1000 Input Code for Gain Control (0 to 1023) Figure 2. Characteristics of PGA Gain optical black (OB) level clamp loop To extract the video information correctly, the CCD signal must be referenced to a well-established optical black (OB) level. The VSP2230 has an autocalibration loop to establish the OB level using the optical black pixel output from the CCD imager. The input signal level of the OB pixels is identified as the real OB level and the loop should be closed during this period while CLPOB is active. During the effective pixel interval, the reference level of the CCD output signal is clamped to the OB level by the OB level clamp loop. To determine the loop-time constant, an off-chip capacitor is required, and should be connected to the COB (pin 28). The time constant T is given in equation 1. T + C 16384 I (min) Where: C is the capacitor value connected to COB, I(min) is the minimum current (0.15 µA) of the control DAC in the OB level clamp loop, and 0.15 µA is equivalent to 1 LSB of the DAC output current. When C is 0.1 µF, then the time constant T is 40.7 µs. Also, the slew rate (SR) is given in equation 2. SR + I (max) C Where: C is the capacitor value connected to COB. I(max) is the maximum current (153 µA) of the control DAC in the OB level clamp loop, and 153 µA is equivalent to 1023 LSB of the DAC output current. Generally, the OB level clamping at high-speed causes clamp noise (or white streak noise). However, the noise will decrease by increasing the capacitor size. On the other hand, a larger capacitor requires a much longer time to restore from the standby mode, or right after the power goes on. Therefore, we recommend a 0.1- µF to 0.22- µF capcitor. However, it depends on the application environment, and making careful adjustments using the cut-and-try method is recommended. (1) (2) |
Numéro de pièce similaire - VSP2230 |
|
Description similaire - VSP2230 |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |