ZK-SJ4 35W Adjustable DC-DC Buck-Boost Power Supply Module – 0.5-30V, 3A CC/CV

The ZK-SJ4 Adjustable DC-DC Power Supply Module is a compact buck-boost converter capable of automatically stepping the input voltage either up or down to provide a stable adjustable DC output.

With adjustable constant voltage (CV) and constant current (CC) control, the module can be used as a general-purpose DC power supply, battery charger, LED constant-current driver, solar charging controller, and adjustable voltage regulator.

It supports an input range of 4.8–30V DC and an adjustable output from 0.5–30V DC, with output current up to 3A and maximum rated power of 35W.

Technical Specifications

• Model: ZK-SJ4
• Converter Type: DC-DC Automatic Buck-Boost Converter
• Input Voltage: 4.8–30V DC
• Output Voltage: 0.5–30V DC Adjustable
• Maximum Output Current: 3A
• Maximum Output Power: 35W
• Control Modes: Constant Voltage (CV) / Constant Current (CC)
• Conversion Efficiency: Approx. 88%
• Module Operating Current: Approx. 30mA
• Switching Frequency: Approx. 180kHz
• Undervoltage Protection: Yes, Self-Recovery
• Anti-Backflow Protection: Yes
• Short-Circuit Protection: Yes
• Operating Temperature: -20°C to +85°C
• Operating Humidity: 0–95% RH
• Module Dimensions: Approx. 68 × 37 × 22mm
• Heatsink Dimensions: Approx. 48 × 16 × 10mm

Automatic Step-Up & Step-Down Conversion

Unlike a conventional buck converter that can only reduce voltage or a boost converter that can only increase voltage, the ZK-SJ4 supports both step-up and step-down operation.

This allows the module to maintain the selected output voltage even when the input voltage is above or below the required output, provided the operating conditions remain within the module's electrical limits.

For example, it can be useful in battery-powered systems where the battery voltage changes as the battery charges or discharges.

Adjustable Voltage & Current

The ZK-SJ4 provides adjustment of both output voltage and current limit.

Constant Voltage (CV) mode regulates the output to the selected voltage under normal load conditions.

Constant Current (CC) mode limits the current to the selected value when the connected load attempts to draw more current.

This CC/CV capability makes the module considerably more versatile than a basic adjustable voltage converter.

Battery Charging Applications

The adjustable CC/CV output makes the module useful for suitable battery-charging projects where the required charging voltage and current can be configured manually.

The module also includes anti-backflow protection, which helps prevent reverse current from the output side toward the input.

Battery charging parameters must always be configured according to the specific battery chemistry, cell count, capacity, and manufacturer's charging requirements.

LED Constant-Current Driver

The adjustable current limit also allows the module to be used as a constant-current LED driver for compatible LED loads.

The voltage and current should be configured before connecting sensitive LEDs to prevent excessive current.

Solar & Variable Input Applications

Because the ZK-SJ4 can both increase and decrease voltage, it is useful in solar and other variable-input power projects where the input voltage may fluctuate.

However, this module should not automatically be considered a full MPPT solar charge controller unless the specific hardware and documentation explicitly provide MPPT functionality.

Applications

Ideal for adjustable DC power supplies, electronics testing, battery charging projects, solar projects, LED constant-current driving, robotics, automotive electronics, DIY bench supplies, battery-powered equipment, voltage regulation, embedded systems, and portable electronics projects.

Important Note

The 3A and 35W specifications are maximum ratings, and the practical continuous output capability depends on input/output voltage difference, ambient temperature, airflow, wiring, and cooling.

Adequate ventilation and heat dissipation should be provided when operating the module at higher power levels.

Always set the required output voltage and current limit before connecting a sensitive load or battery.

This is a non-isolated DC-DC converter. The input and output do not provide galvanic isolation.

Package Includes

1 × ZK-SJ4 35W Adjustable DC-DC Buck-Boost CC/CV Power Supply Module