2.75V to 4.8V Input, 10mA Output, 35µV Ultra Low Noise and Ripple Boost Regulator

The MAX77231 is optimized for boost applications, requiring very low ripple/noise and small PCB space. Output ripple and noise are suppressed to 35µVRMS (in 1MHz BW) by a PMOS linear post-regulator set 0.5V below the boost regulator output to reject noise while optimizing efficiency.

The boost regulator operates using a 1µH/400mA inductor and 2.2µF (0.22 (min) after derating) output capacitance. Fast transient response and stable operation are guaranteed using a current-limited PFM architecture. A PMOS low-noise linear post-regulator attenuates boost converter ripple by ～50dB (10MHz BW) before delivering 11.2V to the load. Other output voltages up to 16.2V can be factory set. The LDO also disconnects the load from the boost during shutdown, allowing the output to fall to 0V (true shutdown). Active discharge can also be activated.

The MAX77231 is packaged in a 9-bump wafer-level package (WLP), providing a compact layout when combined with the inductor and external capacitors. Total solution size is less than 7mm2.

Applications

* Low-Noise Bias Supply * Sensor Bias Supply

* Ultra-Small Solution Size (< 7mm2)

* 35µVRMS (typ) Output Ripple/Noise

* 11.2V/10mA Output

* Output Factory Trimmable from 11.2V to 16.2V

* 125µA No Load Supply Current Output on < 1µA Shutdown Supply Current

* True Shutdown Load Disconnect

* Selectable Active Discharge

* 9-Bump, 1.238mm x 1.238mm x 0.35mm WLP