LD3985M33R

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LD3985M33R Application Field and Working Principle

LD3985M33R is a programmable, high-performance linear regulator from STMicroelectronics that delivers smooth, finely regulated current and voltage stability, with flexibility and reliability for a wide range of applications. It can provide up to 3.3V of output voltage, up to 0.8A of output current, and up to 650mV of dropout voltage, with a temperature range of -40 to 125°C.

LD3985M33R Features

The LD3985M33R has several features that make it ideal for many applications, including:

• Low quiescent current (7.5mA)
• Fast transient response (125µA/µs)
• Extremely low output noise (40µVrms)
• High PSRR (90dB at 1kHz)
• Integrated soft-start time control
• Low input voltage of 2.65V–3.3V
• Programmable output voltage of 0.8V to 3.3V
• Up to 0.8A of output current
• Up to 650mV of dropout voltage
• Integrated PGOOD output
• Thermal shutdown protection
• Very wide operating temperature range (from -40 to 125°C)
• AEC-Q100 compliant
• Small 5x6mm package with thermal pad

LD3985M33R Applications

The LD3985M33R is widely used in always-on and battery-powered systems, such as automotive and industrial applications, computer peripherals and communications equipment, consumer electronics, and portable medical devices. It is also suitable for IoT edge devices and remote controller applications due to its high level of integration and its wide operating temperature range.

LD3985M33R Working Principle

The LD3985M33R is based on a charge pump design, which is a switched-capacitor regulation scheme. The charge pump output voltage is regulated by a feedback loop with an error amplifier, which controls how much charge is transferred to the output capacitor each cycle. This ensures that the output voltage remains stable, regardless of load or input voltage changes.

The regulator also features programmable soft-start and thermal shutdown protection. The soft-start feature minimizes output voltage transients during startup, while the thermal protection ensures that the device will not be damaged due to excessive heat.

The LD3985M33R is ideal for applications requiring low noise, high performance, and efficient operation, with minimal external components. Its high PSRR and low output noise make it well-suited for power converters, battery management systems, and systems that are sensitive to noise.

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