Synchronous buck converters offer design versatility in PoL applications

AP62500 and AP62800 dc-dc converters from Diodes Incorporated provide the freedom to create the smallest possible point-of-load power supply, or the most efficient. Low EMI and fast transient response ensure excellent performance in consumer applications.

The latest synchronous buck converters from Diodes Incorporated give engineers the flexibility to develop point-of-load (PoL) power supplies that are optimized for either efficiency or size. The AP62500 and AP62800 feature selectable switching frequencies, and a choice of three operating modes that increase efficiency, reduce ripple or eliminate audible noise. 

The new dc-dc converters from Diodes require a small number of external components, enabling design engineers to realize compact power-system implementations. 

The AP62500 has a continuous output-current rating of 5 A, while the AP62800’s rating is 8 A. Both buck converters operate from a wide input-voltage range: 4.5 V to 18 V for the AP62500, and 4.5 V to 17 V for the AP62800. The devices’ output voltage can be adjusted down to 0.6 V. This makes the converters ideal for point-of-load power supplies in high-volume consumer products that operate from a 5 V or 12 V distributed power bus. They also provide an efficient solution for FPGA, DSP, and ASIC power supplies. 

The selectable switching-frequency options are 400 kHz, 800 kHz, and 1.2 MHz. At a lower frequency, the design achieves higher conversion efficiency, and at a higher frequency the size of the power supply’s magnetic components can be reduced. 

There are three selectable operating modes: 

  • Pulse frequency modulation (PFM) for high light-load efficiency
  • Pulse width modulation for low output-voltage ripple
  • Ultrasonic, to operate outside the audible frequency range and maintain the switching frequency at higher than 20 kHz

The design of these buck converters minimizes EMI problems. A proprietary gate-driver design mitigates switching-node ringing without having to extend MOSFET turn-on/turn-off times, which would otherwise limit the device’s ability to switch at high frequency. Constant-on-time control results in fast transient response and low output-voltage ripple, as well as providing for better loop stabilization.

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