LNB power management and control IC improves set-top box efficiency

July 02, 2012 // By Paul Buckley
Diodes Incorporated has introduced a family of low power LNB (low noise block) power management and control ICs for use in set-top boxes, TVs with built-in satellite tuners and PC satellite tuner cards.

Designed to increase product efficiency and reliability, the full-featured ZLPM8000 series ICs offers manufacturers the flexibility to address global satellite TV standards.

Three single-output devices are initially being made available: the high-current ZLPM8010 (750 mA) and low-current ZLPM8011 (450 mA), both of which are full-featured and support DiSEqC 1 and DiSEqC 2 standards; and the low-current ZLPM8012 (450 mA), with a reduced feature set and supporting the DiSEqC 1 standard only.

To increase overall STB system efficiency, the ICs' low quiescent current boost converter operates from a standard 12 V power rail and employs a low Rds(on) (270 mΩ) MOSFET power switch. In turn, the converter supplies a very low volt drop (500 mV) LDO regulator, providing control signals and low noise power output to the LNB. The devices' standby operating mode puts it into a deep sleep mode in which current consumption is only 600 µA.

The LNB supply generated by the ZLPM8000 series is highly programmable, being configurable in 0.25 V steps from 10.25 V through to 19.5 V; this enables designers to match with any system architecture and adjust for cable drops or poorly performing LNBs. The devices' integral protection and diagnostic features include over-current limit, line short and open circuit, over temperature shutdown and under voltage alerts.

An integrated 22kHz tone generator provides for DiSEqC and traditional band switching control that is reliable even under no-load conditions. To enable two-way communication between LNB and STB, the ZLPM8010 and ZPLM8011 include the market-leading Zetex LNB DiSEqC receive technology, which allows high reliability detection of a wide range of signals while assuring excellent signal rejection.

Fully configurable via I2C interface or standard logic inputs, the ZLPM8000 series devices are easily tailored to handle regional variations in satellite TV standards. Using the I2C port, designers can access an array of device functionality, including LNB control, output adjustment, a four-level current limit, low-current standby and various line check features.