Diodes AP7372 LDO Regulator Delivers 8μVrms Noise and 90dB PSRR for Precision Electronics

Diodes Incorporated has released the AP7372 low-dropout (LDO) regulator, targeting applications where supply cleanliness is critical to performance. It is designed for powering sensitive components such as data converters, oscillators, and timing circuits, where even small amounts of ripple or noise can degrade results.

The AP7372 maintains a power supply ripple rejection (PSRR) of up to 90dB at lower frequencies and holds above 50dB at 1MHz, helping it suppress noise from upstream switching supplies. Output noise is specified at 8μVrms (10Hz to 100kHz), a level that supports high accuracy in systems such as RF transceivers, precision measurement gear, industrial sensors, and medical imaging equipment.

Electrical Performance and Operating Range

The device can source up to 200mA with a typical dropout voltage of 120mV at full load, improving efficiency when the input and output voltages are close. Input voltage can range from 2.7V to 20V, allowing use from standard system buses, battery supplies, or Li-Ion cells.

Five output variants are available:

• Fixed outputs at 1.8V, 2.5V, 3.3V, and 5.0V
• Adjustable output down to 1.2V

A dedicated adjustment pin on fixed versions allows fine tuning via an external resistor divider, giving flexibility without changing to a fully adjustable design.

Stability and Layout Considerations

The AP7372 is stable with a 2.2μF ceramic output capacitor, which can be increased if lower noise is required. A ceramic input capacitor is also recommended, and a third capacitor can be used to set the soft-start time. With only these few external parts required, board space is kept to a minimum.

The device is packaged in a 1.2mm x 1.0mm U-WLB1012-6 ball-grid array, making it suitable for high-density layouts and portable equipment where power density is a priority.

Soft-Start, Protections, and Power Control

The soft-start function allows designers to control ramp-up time and limit inrush current by selecting an appropriate capacitor value. Built-in current limiting and thermal shutdown provide fault protection, while an enable pin allows the regulator to be switched off when not in use. In shutdown mode, current drops to around 3μA, with a typical operating quiescent current of 66μA.

Applications in the Field

Diodes positions the AP7372 for use in systems where power supply noise and ripple must be tightly controlled, including:

• High-resolution ADC and DAC circuits
• Low phase-noise VCOs and PLLs in RF systems
• Medical diagnostic instruments with sensitive analog stages
• Industrial process control and test equipment
• Communication modules requiring stable local supplies

Availability

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