PRODUCT DESCRIPTION

The AD8180 (single) is high speed 2-to-1 multiplexers. They offer –3 dB signal bandwidth greater than 750 MHz along with slew rate of 750 V/μs. With better than 80 dB of crosstalk and isolation, they are useful in many high speed applications. The differential gain and differential phase error of 0.02% and 0.02°, along with 0.1 dB flatness beyond 100 MHz make the AD8180 ideal for professional video multiplexing. They offer 10 ns switching time making them an excellent choice for pixel switching (picture-in-picture) while consuming less than 3.8 mA (per 2:1 mux) on ±5 V supply voltages. Both devices offer a high speed disable feature allowing the output to be configured into a high impedance state. This allows multiple outputs to be connected together for cascading stages while the “OFF” channels do not load the output bus. They operate on voltage supplies of ±5 V and are offered in 8 and 14-lead plastic DIP and SOIC packages.

 

CARACTERÍSTICAS

Fully Buffered Inputs and Outputs
Fast Channel Switching: 10 ns
Alta velocidad
> 750 MHz Bandwidth (–3 dB)
750 V/μs Slew Rate
Fast Settling Time of 14 ns to 0.1%
Low Power: 3.8 mA (AD8180)
Excellent Video Specifications (RL≥1 kΩ)
Gain Flatness of 0.1 dB Beyond 100 MHz
0.02% Differential Gain Error
0.02° Differential Phase Error
Low Glitch: < 35 mV
Low All-Hostile Crosstalk of –80 dB @ 5 MHz
High “OFF” Isolation of –90 dB @ 5 MHz
Low Cost
Fast Output Disable Feature for Connecting Multiple Devices

 

APLICACIONES

Pixel Switching for “Picture-In-Picture”
Switching in LCD and Plasma Displays
Video Switchers and Routers

 

MAXIMUM POWER DISSIPATION

The maximum power that can be safely dissipated by the AD8180 is limited by the associated rise in junction temperature. The maximum safe junction temperature for plastic encapsulated devices is determined by the glass transition temperature of the plastic, approximately +150°C. Exceeding this limit temporarily may cause a shift in parametric performance due to a change in the stresses exerted on the die by the package. Exceeding a junction temperature of +175°C for an extended period can result in device failure.

 

LAYOUT CONSIDERATIONS:

Realizing the high speed performance attainable with the AD8180 requires careful attention to board layout and component selection. Proper RF design techniques and low parasitic component selection are mandatory.
Wire wrap boards, prototype boards, and sockets are not recommended because of their high parasitic inductance and capacitance. Instead, surface-mount components should be soldered directly to a printed circuit board (PCB). The PCB should have a ground plane covering all unused portions of the component side of the board to provide a low impedance ground path. The ground plane should be removed from the area near input and output pins to reduce stray capacitance.
Chip capacitors should be used for supply bypassing. One end of the capacitor should be connected to the ground plane and the other within 1/4 inch of each power pin. An additional large (4.7 μF–10 μF) tantalum capacitor should be connected in parallel with each of the smaller capacitors for low impedance supply bypassing over a broad range of frequencies. Signal traces should be as short as possible. Stripline or microstrip techniques should be used for long signal traces (longer than about 1 inch). These should be designed with a characteristic impedance of 50Ω or 75 Ω and be properly terminated at the end using surface mount components.
Careful layout is imperative to minimize crosstalk. Guards (ground or supply traces) must be run between all signal traces to limit direct capacitive coupling. Input and output signal lines should fan out away from the mux as much as possible. If multiple signal layers are available, a buried stripline structure having ground plane above, below, and between signal traces will have the best crosstalk performance.
Return currents flowing through termination resistors can also increase crosstalk if these currents flow in sections of the finiteimpedance ground circuit that is shared between more than one input or output. Minimizing the inductance and resistance of the ground plane can reduce this effect, but further care should be taken in positioning the terminations. Terminating cables directly at the connectors will minimize the return current flowing on the board, but the signal trace between the connector and the mux will look like an open stub and will degrade the frequency response. Moving the termination resistors close to the input pins will improve the frequency response, but the terminations from neighboring inputs should not have a common ground return.