500 mA LDOs Stable with Sub-µF Output Capacitors

Compact electronic systems increasingly combine higher current demand with limited PCB area, placing pressure on power designers to reduce capacitor size without compromising stability. Output capacitor value directly influences loop stability and transient response in low-dropout regulators used across vehicles, factory automation and network equipment. In this context, ROHM has introduced the BD9xxN5 Series of LDO regulator ICs, delivering up to 500 mA output current while supporting stable operation with very small MLCC output capacitors.

Extending Nano Cap™ Technology to Higher Currents
The BD9xxN5 Series builds on the earlier BD9xxN1 Series introduced in 2022, which provided 150 mA output current and demonstrated stable operation with output capacitors down to 100 nF using ROHM’s Nano Cap™ control technology. The new series increases the maximum output current to 500 mA—more than three times higher—expanding suitability for higher-power loads while maintaining compatibility with low-capacitance output networks.

Nano Cap™ combines circuit design, semiconductor process and layout optimization to maintain stable control across a wide range of capacitor values and equivalent series resistance (ESR), reducing the risk of oscillation in analog power stages.

Transient Performance with 470 nF Output Capacitance
Evaluation results show output voltage fluctuation of approximately 250 mV when load current changes from 1 mA to 500 mA within 1 µs, using a typical 470 nF output capacitor. This performance enables the use of capacitors well below the multi-µF range commonly required for LDO stability.

In addition to standard small MLCCs of several microfarads and electrolytic capacitors, the devices support ultra-small MLCCs such as 0603M size components (0.6 mm × 0.3 mm) with capacitance below 1 µF—values that have traditionally posed stability challenges. This flexibility supports PCB space reduction and eases component placement in dense designs.




Target Systems Across Automotive, Industrial and Consumer Sectors
The regulators are designed for primary power rails derived from 12 V or 24 V sources. In automotive systems, this includes power supplies for powertrain modules such as fuel injection (FI) and tire pressure monitoring systems (TPMS), body control modules (BCM), and infotainment electronics including instrument clusters and head-up displays.

In industrial equipment, use cases include control electronics for PLCs, remote terminal units (RTU), industrial gateways, and precision analog sensor circuits measuring temperature, pressure or flow. Additional applications include monitoring and control panels for building automation, access control and disaster prevention systems, as well as standby supplies for HMIs and panel equipment.

Consumer applications include control boards in home appliances such as refrigerators, dishwashers and air conditioners, along with always-on power rails in thermostats, doorbells, home security and networking devices.

Design Support
For design verification, ROHM provides high-accuracy SPICE simulation data under the ROHM Real Model framework. Available models include BD900N5xxx-C, BD933N5xxxx-C and BD950N5xxxx-C, allowing engineers to evaluate transient response and stability with specific capacitor selections before hardware prototyping.

By extending stable LDO operation into the 500 mA class while maintaining compatibility with sub-µF output capacitors, the BD9xxN5 Series addresses space and performance constraints common in compact, high-current electronic systems.

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