RE028

RE028 is a Low Drop Out (LDO) voltage regulator macrocell with a fixed 4.5V outputvoltage, rated for loads up to 30 mA. RE028 is designed to be integrated with other analogcells, digital logic, microcontrollers, DSP cores and memory blocks into system-on-chip products. Furthermore, the RE028 is designed to supply radio frequency synthe-sizers and used as a controller for the antenna switch.

The circuit RE028 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 make upthe regulating loop. An over-current and short circuit protection circuit RE028 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)RE028  is necessary for correct functionality.The target reference voltage is 1.231V, delivered, for example, by BG019. Current ref-erence is generated inside the cell through a circuit supplied by a 2.5V ± 0.1Vregulated input voltage on VSAUVC. Remote sense terminal VRADS provides regulationat the load by connecting it to the output terminal near a critical point to improve per-formance of the regulator (e.g., connecting them at the package pin by double-bonding, thus RE028 is avoiding the bonding resistance influence). A ceramic capacitor RE028 of 2.2µF connected from VRAD to ground is needed as external compensation.