36V/600mA compact size step-down DC/DC converter

The XC9704/XC9705 series is a high-voltage-tolerant, space-saving, low-power-consumption synchronous rectification step-down DC/DC converter with a maximum voltage input of 36V.

It supports input voltages of 12V and 24V commonly used in industrial equipment, provides a maximum output current of 600mA suitable for communication devices and sensors, and operates within a wide temperature range of -40°C to 125°C.

With selectable oscillation frequencies of 1.2MHz or 2.2MHz, the XC9704/XC9705 series allows the use of compact peripheral components such as coils and capacitors, achieving a compact mounting area of just 48.7mm². Additionally, with an ultra-low quiescent current of 11μA, the efficiency reaches 90% under conditions of VIN=12V, VOUT=5V, and IOUT=1mA, maintaining high efficiency from light to heavy loads.

These features make the XC9704/XC9705 series ideal for replacing conventional medium to high voltage LDOs, which often have heat generation and size issues.

Moreover, unlike traditional N-channel driver FETs often used in medium to high voltage DC/DC converters, the XC9704/XC9705 series adopts a P-channel driver FET which allows 100% duty operation. This makes the device possible to pass through the input voltage as is even when the input voltage drops below the output voltage setting, ensuring stable operation even with minimal differences between input and output voltages.

Additionally, the Power Good function, which notifies when the output voltage has risen sufficiently, and the soft-start function during startup enables power sequence control to the products and systems after the XC9704/XC9705 series, which is frequently required in industrial applications.

The XC9704 series adopts a fixed PWM control method for low ripple voltage and stable operation, while the XC9705 series uses an automatic PWM/PFM switching control for high efficiency across light to heavy loads, allowing users to select the optimal control method based on their application needs. The product is available in two package types: the SOT-89-5 (4.5 x 4.6 x 1.6mm) for easy mounting (Figure 5) and the ultra-compact and low-profile DFN1820-6G (1.8 x 2.0 x 0.6mm, under development), enhancing design flexibility.

With its 36V operation, 125°C high-temperature compatibility, saving space, and high efficiency under light loads, the XC9704/XC9705 series is a versatile, high-voltage product suitable for various fields, including industrial and general consumer applications.