45V 500mA LDO generates high-quality power lines

January 14, 2016 // By Graham Prophet
LT3066 is a high voltage, low noise, low dropout voltage linear regulator offering precision, programmable current limit, active discharge, a power good flag and improved power supply rejection ratio (PSRR) capability.

The device delivers up to 500 mA output current with a 300 mV dropout voltage at full load. The LT3066 includes an internal NMOS pull-down that discharges the output voltage if either the SHDN pin is driven low or the input voltage is turned off. This rapid active output discharge helps protect the load in applications requiring power conditioning on both start-up and shutdown, such as high-end imaging sensors.

The LT3066 features 1.8V to 45V input voltage range and output voltage is adjustable from 0.6V to 19V. A single REF/BYP pin capacitor provides low noise operation of 25 µVRMS across a 10 Hz to 100 kHz bandwidth, and also reference soft-start functionality, preventing output voltage overshoot at turn-on. Output voltage tolerance is highly accurate at ±2% over line, load and temperature. An additional single INFILT pin capacitor improves PSRR by 15 dB to 20 dB for frequencies from 20 kHz to 1 MHz, with 1 MHz PSRR reaching 60 dB.

The LT3066 operates with a very small, low cost, 3.3 µF ceramic output capacitor, optimising stability and transient response. The device’s PWRGD flag indicates output regulation. One resistor programs the external precision current limit (±10% over temperature). The device’s internal protection circuitry includes reverse-battery protection, reverse-current protection, current limit with foldback, and thermal limiting. The device’s wide input and output voltage ranges, fast transient response, low quiescent current of 64 µA (operating) and <2 µA (in shutdown) suit it for industrial power supplies, avionic power supplies, automotive power supplies, battery-powered systems and instruments requiring optimum run time, and high reliability power supplies requiring more extensive protection.

The LT3066 is available in thermally enhanced 12-lead 3 x 4 mm DFN and 12-lead MSOP packages, both with a compact footprint. The E- and I-grade versions with an operating junction temperature of -40°C to +125°C are priced from $2.00 (1,000)

Linear Technology; www.linear.com/product/LT3066