Developers working with high impedance sources, such as current loops or discontinuous energy sources like harvesters, tend to use a storage element in front of the voltage regulator to buffer the energy. To avoid starting the application before the regulator can provide a stable output voltage (wasting precious energy), the rising ENABLE threshold needs to be set reasonably high. Furthermore, to maximize the application run time, the falling ENABLE threshold must be set reasonably low.
TI’s new TPS62125 buck converter supports both requirements with an accurate adjustable ENABLE threshold and hysteresis. This provides system specific power up and down requirements while consuming only 6μA quiescent current.
How does that work?
The EN pin is connected to an On/Shutdown detector (ON/SD) and an input of the Enable Comparator. With a voltage level of 0.4V or less at the EN pin, the ON/SD detector turns the device into Shutdown mode. In this mode the EN comparator as well as the entire internal-control circuitry are switched off. A voltage level of typ. 900mV (rising) at the EN pin triggers the ON/Shutdown detector and activates the internal reference VREF, the EN comparator and the UVLO comparator.
TheTPS62125 starts regulation once the voltage at the EN pin trips the threshold VEN_TH ON and the input voltage is above the UVLO threshold. It enters soft-start and ramps up the output voltage.
The DC/DC regulator stops operation once the voltage on the EN pin falls below the threshold VEN_TH OFF or the input voltage falls below UVLO threshold.
The enable comparator features a built in hysteresis of 50mV (typ.). This hysteresis can be increased with an external resistor connected to pin EN_hys.
The TPS62125 combines very low power consumption and a high efficiency synchronous step-down conversion over the entire load AND supply voltage range while supporting output voltages between 1.2V to 10V.
TPS62125 includes TI's DCS-Control™ topology, an advanced architecture that provides fast transient and AC load regulation to ensure high DC accuracy. DCS-Control™ enables operation with small and cost competitive external components.
Furthermore, the TPS62125 provides excellent low output voltage ripple over the entire load range, which makes this part ideal for noise sensitive applications.
An EVM is available by ordering TPS62125EVM-044
For more information refer to: http://www.ti.com/product/tps62125