Electronic Components Datasheet Search |
|
MAX7451 Datasheet(PDF) 7 Page - Maxim Integrated Products |
|
MAX7451 Datasheet(HTML) 7 Page - Maxim Integrated Products |
7 / 9 page Video-Signal Conditioners with AGC and Back-Porch Clamp _______________________________________________________________________________________ 7 Automatic Gain Control (AGC) The MAX7450/MAX7451/MAX7452 have an integrated automatic gain-control circuit to ensure the sync ampli- tude is normalized to the standard level, thus normalizing the overall amplitude to a standard level. The accuracy of the normalized amplitude assumes the ratio of active video to sync amplitude is correct in the input video sig- nal. The gain is adjusted automatically by detecting and comparing the amplitude of the sync pulse to a fixed internal reference. If the sync amplitude is less than this value, the overall gain is increased until the sync ampli- tude equals this reference. However, if the sync ampli- tude is high, the overall gain is reduced accordingly. Disable the AGC loop by driving AGCD high. When designing the overall system, it is important to note that the AGC can correct for termination problems. First, disable the AGC and verify that the terminations are cor- rect, and then enable the AGC for proper operation. Output Buffer The output buffer of the MAX7450/MAX7451/MAX7452 is designed to drive either standard video loads or high-impedance loads, independent of the buffer gain. Logic levels on GSET and AGCD set the gain of the MAX7450/MAX7451/MAX7452. Table 1 shows the dif- ferent gain-setting configurations. Noise Filter The MAX7450/MAX7451/MAX7452 feature a simple 2nd- order lowpass filter to reject out-of-band noise that may be introduced by the long cable connection between the cameras and the switching matrix. LOS Detector The LOS detector of the MAX7450/MAX7451/MAX7452 outputs a logic high when the sync is not present (loss of video signal) for at least 15 horizontal lines on the input. This can be used to indicate a fault condition of the camera or cable. Applications Information Connecting the MAX7450/MAX7451 to a Crosspoint Switch The MAX7450/MAX7451/MAX7452 are designed to directly interface to a video crosspoint switching device such as those used in security systems (see Figure 2). The MAX7450/MAX7451 clamp the video output to GND, making the devices an ideal interface to the MAX4358 crosspoint switches and the MAX4455 OSD. The MAX7450/MAX7451 and the MAX4455 have their outputs referenced to ground, ensuring the amplitudes and the brightness of the OSD relative to the video signal are accurate. Interfacing the MAX7452 to an ADC The MAX7452 can be directly connected to an ADC or video decoder as shown in Figure 3. The video output of the MAX7452 is DC-coupled to a single-ended video input on the ADC. The voltage on the BPLVL pin sets the black level of the video signal at the output of the MAX7452. Use a stable voltage reference for the BPLVL voltage, ideally the same reference that is used AGCD GSET OUTPUT 00 1VP-P fixed 01 2VP-P fixed 10 VOUT = VIN 11 VOUT = 2VIN Table 1. Gain-Control Settings MAX7450 MAX7451 MAX7450 MAX7451 CAM 1 MAX4358 32 x 16 CROSSPOINT MAX4455 OSD MAX4455 OSD CAM 32 MONITOR 1 MONITOR 16 Figure 2. MAX7450/MAX7451 in a 32 x 16 Crosspoint Application |
Similar Part No. - MAX7451 |
|
Similar Description - MAX7451 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |