RE027

RE027 is a Low Drop Out (LDO) voltage regulator macrocell with a fixed 2.8V outputvoltage, rated for loads up to 130 mA. It is designed to be integrated with other analogcells, digital logic, microcontrollers, DSP cores and memory blocks into system-on-chip products.

The circuit RE027 consists of a PMOS pass device, an error amplifier and a feedback resis-tive network, sized to achieve the required closed loop gain. These blocks of RE027 make upthe regulating loop. An over-current and short circuit protection circuit has beenincluded to limit the output current delivered by the regulator, thus avoiding destructionin case of a short circuit.

An external reference voltage (bandgap voltage)RE027 is necessary for correct functionality.The target reference voltage is 1.231V delivered, for example, by BG019. Double padson the supply voltage VBAT3B/VBAT3BB and output voltage VCRADIOA/VCRADIOAA are usedto reduce the total output resistance. Current reference of RE027 is generated inside the cellthrough a circuit supplied by a 2.5V ± 0.1V regulated input voltage on VSAUVC. Remotesense terminal VCRADIOS provides regulation at the load by connecting RE027 to the outputterminal near a critical point to improve performance of the regulator (e.g., connectingthem at the package pin by double-bonding, thus avoiding the bonding resistanceinfluence). A capacitor of 2.2 µF connected from VCRADIOA/VCRADIOAA to ground isneeded as external compensation.