UDM2826I Integrated DC-DC Buck Step-Down Power Module ( 2.7V-5.5V Input, 1.0V-3.3V Output )

Features

Ferrite Ceramic Substrate with Integrated Power Inductor and Capacitors,Low EMI Noise, Ultra-Compact 

Synchronous Rectification Technology for High Efficiency

Control Mode Selection: Automatic PFM/PWM Switching or Forced PWM Mode

Light Load Operation with Low Ripple Voltage PFM Mode

Voltage Accuracy of ±2.5% Over Full Load Current Range

Wide Input Voltage Range: 2.7V to 5.5V

Maximum Load Current: 1.5A (800mA for Output Voltages of 2.5V or 3.3V) 

Fixed Output Voltage: 1.0V to 3.3V (Factory Set)

Internal Soft Start and Over current Protection

Description

The UDM2826I series is designed for space-constrained or noise-sensitive low-power buck DC-DC converters. The device uses an inductor-embedded ferrite substrate to reduce radiated EMI noise and conducted noise. It is encapsulated in a plastic package to enhance mounting reliability.

By adding an output capacitor, it can be used as an LDO alternative. Its low noise and easy-to-use features ensure reliable power quality.

The device, when set to automatic PFM/PWM switching mode (MODE=L), operates in PFM mode at light loads to extend battery life. Under heavier loads, it automatically switches to PWM mode using synchronous rectification technology to maintain high efficiency.

When set to forced PWM mode (MODE=H), the device provides excellent output voltage accuracy over the entire load range. It maintains a voltage accuracy of ±2.5% over the current range of 0 to 1.5A.

When used as a reference voltage source, it is recommended to set the device to forced PWM mode (MODE=H). This can be achieved by directly connecting the MODE pin to VIN.

Typical Application Circuit

UDM2826I Typical Application Circuit

PIN CONFIGURATION

Dimensions

Pin Functions

Electrical Characteristics

Absolute Maximum Ratings

Electrical Characteristics（Ta = 25℃)

1 The external capacitor (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 decreases, the converter will automatically enter PFM (Pulse Frequency Modulation) mode. In PFM mode, the device operates in discontinuous current mode with sporadic switching pulses to maintain high efficiency under light load conditions.

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 ±2.5% of the nominal voltage. By increasing the output capacitance, the output ripple voltage in PFM mode can be further reduced.

The transition between PFM and PWM modes is also smooth. The current threshold for transitioning between PFM and PWM modes depends on factors such as Vin and Vout, but the approximate threshold is around (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 (2.0V typical) before the device starts up. The UVLO feature prevents uncertain operation at low Vin levels.

Soft Start

The device features an internal soft start function to limit inrush current during startup. The soft start system gradually increases the switch time from the minimum pulse width to normal operation. Due to this feature, the output voltage gradually increases from zero to the rated voltage during startup. The nominal soft start time is 0.3ms.

EN

When the EN pin is set to a high logic level, the device begins operation and starts up with a soft start. The EN pin must not be left floating; if it is open-circuit, the device may work under light load but fail to operate under heavy load.

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

100% Duty Cycle Operation

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

When Vin and Vout become close and the duty cycle approaches 100%, the switching pulses will skip the nominal switching cycle, and the output voltage ripple may be greater than under other conditions. However, this does not indicate a fault in the device.

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