Switching regulator delivers 120mA with high efficiency

2nd September 2021
Mick Elliott

The LT8604 high speed synchronous monolithic step-down switching regulator from Analog Devices delivers up to 120mA with high efficiency at constant switching frequency, even up to 2.2MHz.

It is available with an evaluation board from Anglia Components.

The device accepts a wide input voltage range up to 42V, and consumes only 2.5μA of quiescent current.

It integrates top and bottom power switches with all necessary circuitry minimising the need for external components as demonstrated in the typical application circuit diagram below.

In addition the regulator utilises low ripple Burst Mode operation enabling high efficiency down to very low output currents while keeping the output ripple below 10mVP-P.

Additional integrated features provide for flexible and robust operation such as the internal compensation with peak current mode topology allows the use of small inductors and results in fast transient response and good loop stability.

The EN/UV pin has an accurate 1V threshold and can be used to program VIN under voltage lockout or to shut down the LT8604 reducing the input supply current to just 1μA.

A PG flag signals when VOUT is within ±7.5% of the programmed out-put voltage as well as any fault conditions whilst thermal shutdown provides additional protection.

The LT8604 step-down switching regulator boasts > 90% efficiency at low load currents as demonstrated in the graph below.

It is available in a small 10-Lead 3mm × 2mm DFN package with exposed pad for low thermal resistance, devices are specified for operation over the temperature range -40°C to +125°C and -40°C to +150°C for J suffix part numbers.

The device suits applications requiring high efficiency at very light load currents such as Industrial Sensors, Industrial Internet of Things (IIoT), 4mA to 20mA Current Loops, Flow Meters, Portable battery powered instruments and Automotive power supplies.

The EVAL-LT8604-AZ evaluation board is available to support designers, the board features the LT8604 regulator in 10-Lead 3mm × 2mm side-wettable DFN package.

The board is designed to deliver 120mA at 5V output from a 5.9V to 42V input, with switching frequency of 0.7MHz.

The wide input range allows a variety of input sources, such as automotive batteries and industrial power supplies.

The board uses peak current mode control with minimum on-time of as small as 35ns allowing high step-down conversion even at high frequency.

The LT8604 switching frequency can be programmed via an oscillator resistor over a 200kHz to 2.2MHz range, the default frequency of the evaluation board is 700kHz.

With an EMI filter installed, the EMI performance of the board is detailed in the user guide, the red line in the Radiated EMI Performance graph is CISPR25 Class 5 peak limit, and the graph shows that the circuit passes the peak limit test from 30MHz to 1GHz, with a wide margin.

Anglia are offering customers a free evaluation board and samples of the LT8604 high speed synchronous monolithic step-down switching regulator.

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