The regulator outputs are set to 12, 13, 18, or 20 V by the VSEL terminals. Additionally, it is possible to increase the selected voltage by 1 V to compensate for the voltage drop in the coaxial cable (LLC terminal HIGH). The LNBR combines a tracking switching regulator and low-noise linear regulators. Logic inputs (VSEL0, VSEL1, and LLC) select the desired output voltage. A tracking current-mode buck converter provides the linear regulator input voltage that is set to the output voltage plus typically 0.8 V. This maintains constant voltage drop across the linear regulators while permitting adequate voltage range for tone injection. The device is supplied in a 24-pin plastic DIP with batwing tabs (A8284SB), or a 24-lead SOIC power-tab package (A8284SLB). In both cases, the power tab is at ground potential and needs no electrical isolation. |