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Video amplifiers operate at 1.8V single supply

Posted: 01 Aug 2007 ?? ?Print Version ?Bookmark and Share

Keywords:1.8V video amplifiers? power supply? low power design?

Maxim Integrated Products said that its new MAX9509/MAX9510 is the industry's first 1.8V video amplifiers. The MAX9509/MAX9510 push the power consumption limit to a new low by operating the video amps at only 1.8V. Along with such a low-power supply, the devices leverage the company's DirectDrive technology to generate a clean, internal negative supply.

By combining the internal negative power supply with the external positive 1.8V supply, the MAX9509/MAX9510 drive a 2VP-P video signal into a 150 load. Operating at the 1.8V single power supply, these amplifiers use 70 percent less power; they consume 5.8mW quiescent power and 11mW average power.

If customers use the 1.8V digital supply, they can even eliminate the analog supply, which can greatly simplify designs. Offered in a 2mm x 2mm TDFN, these amplifiers are perfect for portable applications such as digital still cameras, digital camcorders and mobile phones.

The MAX9509/MAX9510 achieve their exceptional performance levels by combining the 1.8V operation with the Company's DirectDrive technology to create the full 2VP-P output range. Other IC manufacturers that offer a technology similar to DirectDrive have charge-pump circuitry that generate so much noise that the device typically becomes unusable.

Low power device
The MAX9509/MAX9510 consume over 70 percent less average power than existing solutions. MAX9509 has an integrated filter and consumes only 11mW average power. The filter-less counterpart, MAX9510, consumes only 10.4mW average power. A typical competitive video filter amp operating at 3.3V burns at least 46mW.

So how does the 1.8V video amplifiers reduce video DAC power consumption? The power saving stems from the drive current and the supply voltage, said Maxim. The drive current is proportional to the full-scale voltage level and inversely proportional to the output resistor value. The MAX9509/MAX9510 input video signal is only 0.25VP-P, a factor of 4 lower than the normal full-scale video signal. Moreover, the DAC's output resistor value can be increased from 37.5 to 150, another factor of 4. Thus, the devices' drive current is reduced by a total factor of 16. Finally, with the DAC's output swing down to 0.25VP-P, the video DAC supply voltage can be lowered from 3.3V to 1.8V. With the drop in both driver current and supply voltage, the DAC power consumption is substantially reduced.

Additonal functionalities
The high PSRR spec (49dB at 100kHz) of the MAX9509/MAX9510 is designed to reject the noise from the digital power supplies. Customers can use the digital 1.8V power supply to power these analog video amps and potentially eliminate the analog supply to save space and cost.

The new devices also integrate additional Benefits from the DirectDrive Technology, said Maxim. Before, setting the video black level near ground required capacitors. The DirectDrive technology features an integrated charge pump and an internal linear regulator to create a clean negative power supply to drive the sync below ground. Thus, the DirectDrive approach eliminates bulky and sometimes costly output coupling capacitors and sets the video black level near ground. This further allows designers to save board space and reduce costs.

For added design flexibility, the MAX9509/MAX9510 support DC-coupled inputs and can be directly connected to the output of a video DAC. The devices also feature a transparent input sync-tip clamp, allowing AC-coupling of input signals with different DC biases.

To provide additional operational protection, the MAX9509/MAX9510 are offered in the -40C to 125C automotive temperature range. The MAX9509 and MAX9510 are priced at 49 cents and 45 cents, respectively for 1,000-unit quantities. The MAX9509 is available in an 8-pin TDFN and the MAX9510 in an 8-pin ?MAX. Samples and evaluation kits are also available.

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