Low Dropout Regulator: Rohm BD933N1WG-CTR Circuit Analysis Report

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Report Summary

In the automotive sector, the number of electronic components mounted has been increasing year by year due to technological innovation accompanying advances in electric vehicles and automotive driving technology, and the reduction of mounted components (capacitors) demand is increasing for miniaturization, low power consumption and cost reduction. For Low Dropout Regulator (LDO) application it is important to keep the stable operation of circuits even without output capacitor.

This product is based on Rohm “Nano Cap™” and “QuiCur™” technologies introduced in 2022, and has reduced capacitor capacity and improved response performance in the power supply circuit as an in-vehicle LDO IC.

In this report, circuit analysis of Rohm BD933N1WG-CTR is performed  to clarify the device layout and circuit configuration.

Product characteristics

• 45V withstand voltage, output current 150 mA, current consumption 28 μA (Typ), output voltage ±2.0%
• Low-dark-current linear regulator using Rohm’s original circuit technologies “Nano Cap™” and “QuiCur™”. The output capacitor can be used from 100nF (Typ) and has an overwhelming transient response even in small capacity.
• From the results of this circuit analysis, as a characteristic of the circuit, the frequency characteristics are improved by making the error amplifier in the LDO into a two-stage configuration. In addition to the voltage feedback control used in the common LDO, it has been confirmed that the current feedback control (current detection by low resistance) used in the DC-DC converter is applied.