Ultra-low quiescent current converter extends battery life in always-on designs

Keeping a battery-powered product alive between active events is largely a function of how little current the power supply draws when nothing is happening. The NEX30606 step-down converter addresses this by entering an ultra-low-power mode at light loads, where most internal circuitry is switched off.

When load demand increases, the converter transitions automatically to PWM mode using Constant On Time (COT) control. This provides fast transient response and low output ripple across the full load range without any intervention from the host system. The switching frequency scales linearly with load current in power save mode, keeping efficiency high at the microampere-range loads which are typical of a sleeping IoT node.

Output voltage is configured with a single external resistor connected to the voltage set (VSET) pin, selecting from 16 fixed voltages between 0.7V and 3.3V. The resistor value is read once at start-up before the sensing current is disconnected entirely, so the configuration process has no impact on the steady-state power budget. The wide input voltage range accommodates single-cell Li-ion and Li-MnO2 cells as well as two- and three-cell alkaline packs, giving designers flexibility in selecting the source without changes to the surrounding circuit.

An internal soft-start limits inrush at power-up, which is particularly useful when operating from high-impedance sources such as coin cells. Cycle-by-cycle overcurrent limiting on both power switches, hiccup-mode short-circuit protection, and thermal shutdown with automatic recovery reduce the need for external protection components, keeping the total solution compact.