MAX25239/MAX25240 Buck-Boost Converters

ADI's MAX25239 and MAX25240 are small, synchronous, buck-boost converters with integrated H-bridge switches. These ICs provide a fixed-output regulation voltage and an externally adjustable output voltage in the 3 V to 20 V range with an input voltage above, below, or equal to the output regulation voltage. The IC has typical 8.2 A and 10 A input current limit options and can support continuous load currents up to 6 A, depending on the input-to-output voltage ratio and operating frequency, with a wide input voltage range of 2 V to 36 V.

The MAX25239 and MAX25240 have three switching frequency options: 2.1 MHz, 400 kHz, and 200 kHz. The 2.1 MHz high switching frequency allows small external components and reduced output ripple and guarantees no AM band interference; the 400 kHz and 200 kHz switching frequencies offer better efficiency and relieve power consumption concerns. The SYNC input allows three operation modes: skip mode with ultra-low quiescent current, forced fixed-frequency PWM operation, and synchronization to an external clock. The IC also includes spread-spectrum frequency modulation to minimize electromagnetic interference (EMI).

The MAX25239 and MAX25240 feature a power-OK (POK) indicator, undervoltage lockout, overvoltage protection, cycle-by-cycle current limit, and thermal shutdown. The ICs are available in a small, 4.25 mm x 4.25 mm x 0.75 mm, 22-pin FC2QFN package.

The MAX25240 evaluation kit (MAX25240EVKIT#) is a fully assembled and tested application circuit that simplifies the evaluation of the MAX25240 400 kHz, 36 V buck-boost converter. All installed components are rated for the automotive temperature range. Various test points and jumpers are included for evaluation.

The standard EV kit comes with the MAX25240AFFF/VY+ installed (11.5 V, 400 kHz) and can also be used to evaluate other MAX25240 variants with minimal component changes shown in the MAX25240 EV Kit bill of materials (BOM).