STEVAL-A6983IV1 [STMicroelectronics]

The STEVAL-A6983IV1 is an evaluation board based on the A6983I, 38 V, 10 W synchronous iso-buck converter designed for isolated applications.

The primary output voltage can be accurately adjusted, whereas the isolated secondary output is derived by using a given transformer ratio. No optocoupler is required.

The primary sink capability up to -4.5 A (even during soft-start) allows a proper energy transfer to the secondary side as well as enables a tracked soft-start of the secondary output.

The control loop is based on a peak current mode architecture and the device operates in forced PWM.

The 390 ns blanking time filters oscillations, generated by the transformer leakage inductance, making the solution more robust.

The compact QFN-16 3x3 mm package and the internal compensation of the A6983I help minimizing design complexity and size.

The switching frequency can be programmed in the 200 kHz - 1 MHz range with optional spread spectrum for improved EMC.

The EN pin provides enable/disable functionality. The typical shutdown current is 2 uA when disabled. As soon as the EN pin is pulled up, the device is enabled and the internal 1.3 ms soft start takes place.

The A6983I features a power-good open collector that monitors the FB voltage. Pulse by pulse current sensing on both power elements implements an effective constant current protection and thermal shutdown prevents thermal runaway.

Due to the primary reverse current limit, the secondary output is protected against short-circuit events.

• Designed for iso-buck topology
• 4 to 38 V input voltage range
• Up to 10 W deliverable power (depending on the application conditions)
• Isolated output voltage unregulated
• Optional postregulation (not mounted, layout foreseen at the bottom)
• Embeds the transformer
• Regulation at the primary side, no optocoupler required
• 200 kHz to 1 MHz programmable switching frequency
• Suitable for external synchronization
• Power-good signal available
• Enable
• Input EMI filter embedded
• Selectable spread spectrum function for improved EMC performance