MAXIM MAX7453CSA

The MAX7453 is a low-cost, triple-channel video reconstruction filter for S-video and CVBS video-signal applications. This device is ideal for anti-aliasing and DAC smoothing video applications such as set-top boxes, DVD players, hard-disk recorders (HDRs), and personal video recorders. This filter operates from a single +5V supply. It is optimized for NTSC, PAL, and standard-definition TV (SDTV) video systems. Each channel consists of a lowpass filter and an output buffer capable of driving one (YOUT, COUT) or two (CVOUT) standard 150Ω video loads. The output buffers can drive either an AC or a DC load such that the blanking level voltage after the backmatch resistor is less than 1V. The Y and C video inputs are summed to produce the composite video output. The MAX7453 has a maximally flat frequency response. The primary function of the MAX7453 is to filter and buffer the encoder DAC outputs that contain digital video information in applications such as set-top boxes, HDRs, DVD players, and digital VCRs. This device reconstructs and cleans up analog video signals. The MAX7453 consists of a lowpass filter and a +6dB -gain output video buffer. The luma (YIN) and chroma (CIN) video inputs are summed internally to provide the composite (CVOUT) video output. These devices operate from a single +5V supply. The filters have a nominal cutoff frequency optimized for NTSC, PAL, and SDTV. The reconstruction filter consists of two 2nd-order Sallen-Key stages. The Butterworth-type response features a maximally flat passband for NTSC and PAL bandwidths. The stopband offers 42dB (typ) of attenuation at sampling frequencies of 27MHz and above. The YOUT and COUT buffers have a fixed +6dB gain capable of driving one standard 150Ω video load with a 2VP-P signal. The CVOUT buffer has a fixed +6dB gain, capable of driving two 150Ω video loads. The MAX7453 can drive an AC load or drive the video load directly without using the large output capacitor. The output buffer of all the channels drives a DC load with an output blanking level of less than 1V. When sync pulses in the luma signal (Y) are detected, the DC restore loop is activated. The function of the loop is to set the sync tip of the video signal to the desired DC level of 0.8V for YOUT and COUT, and to set the average DC voltage of COUT at 1.6V.

• Triple-Channel Filter and Buffer for CVBS and Y/C (S-Video) Video Signals
• Filter Response Ideal for NTSC, PAL, and Interlaced SDTV Signals
• 42dB (typ) Stopband Attenuation at 27MHz
• -0.3dB (typ) Passband Response
• <1V Blanking Level Allows DC-Coupled Output
• CVOUT Drives Two 150Ω Video Loads
• YOUT and COUT Drive One 150Ω Video Load
• +5V Single-Supply Voltage
• 8-Pin SO Package

• Set-Top Boxes/HDRs/DVDs
• Security Cameras/Digital Cameras
• Game Consoles
• Digital VCRs
• Every Composite, S-Video Output for NTSC, PAL, and SDTV