Out in Front: December 7, 1995

Although a positive supply regulator usually acts solely as a current source, some applications require both sourcing and sinking. For these applications, Linear Technology’s LT1118 family of low-dropout regulators can source and sink as much as 800 and 400 mA, respectively, for 2.5, 2.85, and 5V outputs. Applications for these devices include bus terminations, which must maintain regulation under load-overshoot and -undershoot conditions, and supply splitters, which create a new midspan reference ground in a single-supply system to minimize common-mode system problems and to simplify overall design.

The 2.85V model is for SCSI line termination, in which the active negation improves noise margin; the device can terminate as many as 27 SCSI lines. All devices have fast transient response for quick recovery from load changes and are stable with a capacitive load of greater than or equal to 2.2 µ. Maximum dropout voltage is 1.3V, and output regulation is 1%. Quiescent, unloaded supply current is 800 µ in shutdown mode, the output goes high-impedance, and supply current falls to less than 10 µ. The LT1118 devices are available in three-lead SOT-223 and eight-lead SOIC packages and cost $2.55 (1000). -- by Bill Schweber

Linear Technology Corp, Milpitas, CA. (800) 454-6327.