Quad-Triple, SPDT, RGB Switches with 250MHz Video Buffer Amplifiers

The MAX498/MAX499 are high-speed, quad/triple, single-pole/double-throw video switches with on-board closed-loop buffer amplifiers. The buffer amplifiers feature +6dB gain (AVCL = 2V/V), 250MHz -3dB bandwidth, 70MHz 0.1dB gain flatness, and 1250V/µs slew rate. Fast switching time (3ns) and fast settling time (12ns for a 4V step) make these devices excellent choices for a wide variety of video applications. The low differential gain/phase errors (0.03%/0.06°) and wide bandwidth make them ideal for both composite-video and RGB applications. The amplifiers are capable of delivering ±2.5V into back-terminated 50Ω or 75Ω cables, and they deliver ±2V to a 75Ω load, allowing multiple cables to be driven from a single output.

For implementation of large switch arrays, a low-power disable mode places the amplifier outputs in a high-impedance state. Channel selection and output enable/disable are controlled by four TTL/CMOS-compatible logic inputs. Each video input is isolated by an AC-ground pin, which minimizes channel-to-channel capacitance and reduces crosstalk to 90dB at 10MHz.

The four-channel MAX498 dissipates 390mW (typical) from ±5VDC power supplies with all output buffers enabled. Power consumption is reduced to 130mW with all buffers disabled. The corresponding dissipation for the three-channel MAX499 is 300mW enabled and 100mW disabled.

Applications

* Broadcast and High-Definition TV Systems * Broadcast-Quality Composite-Video Multiplexing * Medical Imaging * Multimedia Products * Video Editing * Video Routing and Switching Systems * Workstations

* High Speed:

* 250MHz Small-Signal -3dB Bandwidth

* 135MHz Full-Power -3dB Bandwidth

* 70MHz 0.1dB Gain Flatness

* 1250V/µs Slew Rate

* 12ns to 0.1% Settling Time

* 0.03°/0.06% Differential Phase/Gain Error

* 2pF Input Capacitance

* 3ns Channel-Switching Time

* 120mVp-p Channel-Switching Transient

* Three-State Output Allows Large Switch Arrays

* Directly Drives 50Ω or 75Ω Back-Terminated Cables