LT1076-5

The LT1076-5 is a 2A fixed 5V output monolithic bipolar switching regulator which requires only a few externalparts for normal operation. The power switch, all oscillator and control circuitry, all current limit components, and an output monitor are included on the chip. The topology is a classic positive "buck" configuration but several design innovations allow this device to be used as a positive-to- negative converter, a negative boost converter, and as a flyback converter. The switch output is specified to swing 40V below ground, allowing the LT1076-5 to drive a tapped inductor in the buck mode with output currents upto 4A.

The LT1076-5 uses a true analog multiplier in the feedback loop. This makes the device respond nearly instanta- neously to input voltage fluctuations and makes loop gain independent of input voltage. As a result, dynamic behav- ior of the regulator is significantly improved over previousdesigns. On-chip pulse by pulse current limiting makes the LT1076- 5 nearly bust-proof for output overloads or shorts. The input voltage range as a buck converter is 8V to 60V, but a self-boot feature allows input voltages as low as 5V in the inverting and boost configurations.

The LT1076-5 is available in a low cost 5-lead TO-220 package with frequency pre-set at 100kHz and current limit at 2.6A. See Application Note 44 for design details.