Design of Capacitor-Less High Reliability LDO Regulator with LVTSCR Based ESD Protection Circuit Using Current Driving Buffer Structure

Abstract

The peak voltage depending on the load current can be affected by the external capacitors installed in the output stage of the LDO regulator. However, the capacitor-less LDO regulator proposed in this study was applied a current driving buffer structure between the output stage of the error amplifier and the path transistor. Therefore, the proposed LDO regulator maintained a stable output voltage regardless of the load current by controlling an effective overshoot/undershoot voltage. In addition, the proposed LDO regulator has a built-in LVTSCR based on the ESD protection circuit. As most IC circuits are malfunctioned and destroyed by the ESD phenomenon, the reliability was verified through the built-in ESD protection circuit of the proposed LDO regulator. The proposed LDO regulator with the current driving buffer structure can effectively control the peak voltage. As a result of the measurement, the undershoot voltage of 22 mV and the overshoot voltage of 19 mV were maintained when the load current of 250 mA was provided under the conditions of 3.3 V to 4.5 V and the output power voltage of 3 V. The proposed ESD protection circuit is also guaranteed to function at temperatures as high as 500 K.

Keywords

• capacitor-less LDO
• ESD protection
• load transient response
• current buffer structure
• SCR based ESD protection
• LDO regulator