5V Step-Down Switching Regulator

The LT1076-5 is a 2A fixed 5V output monolithic bipolar switching regulator which requires only a few external parts 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 up to 4A.

The LT1076-5 uses a true analog multiplier in the feedback loop. This makes the device respond nearly instantaneously to input voltage fluctuations and makes loop gain independent of input voltage. As a result, dynamic behavior of the regulator is significantly improved over previous designs.

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- and 7-lead TO-220 packages with frequency pre-set at 100kHz and current limit at 2.6A. See Application Note 44 for design details.

Applications

* 5V Output Buck Converter

* Tapped Inductor Buck Converter with 4A Output at 5V

* Positive-to-Negative Converter

* Fixed 5V Output

* 2A On-Board Switch

* 100kHz Switching Frequency

* 2% Output Voltage Tolerance Over Temperature

* Greatly Improved Dynamic Behavior

* Available in Low Cost 5- and 7-Lead Packages

* Only 9.5mA Quiescent Current

* Operates Up to 60V Input