UDM2520I Integrated DC/DC Buck Step-Down Power Module ( 2.3V-5.5V Input, 0.8V-3.3V Output )

Features

Integrated power inductor on a ferrite ceramic substrate, ultra-small area (5mm²), low EMI noise 

Integrated capacitor in a single-package mold, high reliability for surface mount

Synchronous rectification technology achieves high efficiency

Automatic PFM/PWM mode switching function

Low ripple voltage PFM mode is used under light load conditions

Achieves 2% voltage accuracy over the full load current range. Wide input voltage: 2.3V to 5.5V

Maximum Load Current: 600mA(dependent on output voltage) 

Fixed Output Voltage: 0.8V~3.3V(Factory Set)

Internal Soft Start and Overcurrent Protection

Description

The UDM2520I series is a low-power buck DC-DC converter suitable for space-constrained or noise-sensitive applications. The device features an embedded inductor on a ferrite substrate, which reduces radiated EMI noise and conducted noise. It also uses a plastic one-piece encapsulation to enhance mounting reliability.

By adding input/output capacitors, it can be used as an alternative to an LDO regulator. Its low noise and ease of use ensure reliable power quality.

The device can smoothly switch between PFM mode and PWM mode based on the load current. Under light load conditions, it automatically switches to PFM mode to extend battery life; under heavier load conditions, it automatically switches to PWM mode to ensure low ripple and high efficiency. The device provides excellent output voltage accuracy even in PFM mode. It maintains 2% output voltage accuracy over the entire load current range (0 to 600mA).

Typical Application Circuit

PIN CONFIGURATION

 Pin Functions

Electrical Characteristics

Absolute Maximum Ratings

Electrical Characteristics（Ta = 25℃)

1.The external capacitor (Cin : 4.7μF,  Cout : 10μF) should be placed near the device to ensure proper operation.  

2.The above characteristics were tested using the test circuit described in Section 8.

Detailed description

PFM / PWM Modes

If the load current drops to the light load range, the point-of-load (POL) power supply will automatically enter PFM mode. In PFM mode, the device operates in discontinuous current mode with sporadic switching pulses to maintain high efficiency at light loads.

The device uses constant on-time control in PFM operation, which produces low ripple voltage and precise output voltage compared to other PFM architectures. Due to this architecture, the DC output voltage can be maintained within ±2% of the nominal voltage. By increasing the output capacitance, the output voltage ripple in PFM mode can be further reduced.

The transition between PFM and PWM modes is smooth, and the switching current value between the two modes depends on factors such as Vin and Vout. However, the threshold range is typically (100~200) mA.

UVLO (Undervoltage Lockout)

Even if the EN pin is held high, the input voltage (Vin) must reach or exceed the UVLO voltage (1.4V typical) before the device starts up. The UVLO feature prevents undefined operation at low Vin levels.

Soft Start

The device features an internal soft-start function that limits inrush current during startup. The soft-start system gradually increases the switching time from the minimum pulse width to normal operation. Due to this feature, the output voltage gradually rises from zero to the rated voltage during startup. The nominal soft-start time is 1ms.

EN

When the EN pin is set to a high logic level, the device begins operation and starts up with a soft-start sequence. For normal operation, the EN pin must be connected to a logic high level and must not be left floating. If the pin is left open, the device may operate under light load conditions but will fail to function properly under heavy load conditions.

Pulling the EN pin to a logic low level will force the device to shut down.

100% Duty Cycle Operation

The device can operate in 100% duty cycle mode, where the high-side switch is always on, providing a lower input-to-output voltage difference.

When Vin  and Vout become close and the duty cycle approaches 100%, the switching pulses may skip the nominal switching cycle, resulting in higher output voltage ripple compared to other conditions. However, this does not indicate a fault in the device.

Overcurrent Protection (OCP)

When the output current reaches the OCP threshold, the device will reduce the switching duty cycle, lowering the output voltage. If the OCP event is cleared within the blanking time (20μs typical), the output voltage will automatically recover to the nominal value. If the OCP event persists beyond the blanking time, the device will shut down. After shutdown, the device can be restarted by toggling the Vin or EN voltage.

Test Circuit

PCB Pad Recommendations

Mark information

Recommended Soldering Process

Recommended Reflow Soldering Profile

Note: For bulk and opened original packaging products, store them in a dry cabinet (the relative humidity in the dry cabinet should be kept below 10%). For unopened original packaging products, store them in a dry cabinet whenever possible.

Packaging Information

Reel and Tape Main Dimensions