Silanna Semiconductor PoL Buck Converters for Telecommunications and Networking Equipment

The SZPL8216A COT (constant on-time) controlled devices integrate the functions of the output gate drivers, DC/DC COT controller, and output power blocks in a single compact 21-lead, 3mmx4mm QFN (quad-flat no-leads) package to give the best power density with a minimum external component count.

Their compact size makes it possible for designers to have ultra-compact PCB layout, high-efficiency, and high-power density in space-constrained applications like networking equipment, telecommunications, and enterprise servers.

SZPL8216A's Features

The three different versions (the SZPL8216A-A, SZPL8216A-B, and SZPL8216A-C) deliver up to 12 Amps with 94% efficiency and have varying voltage references, AVCC operating voltages, and fault mode behaviours.

The products feature a 600kHz to 1MHz selectable switching frequency that enables users to make design-specific decisions for optimising their component size against efficiency. In addition, the capability of operating at 1MHz implies that designers can use a smaller output filter to minimise the total PCB solution size.

These COT controlled converters use Silanna’s exclusive S-Loop control architecture, which provides an almost immediate response to load transitions with minimum increments in overshoot or undershoot – this is the kind of performance that would benefit FPGA (field-programmable gate array) and multi-core CPU applications that require a stable power supply voltage and power quickly with high current load transients.

Other features include:

• Pre-biased start-up
• Diode emulation mode (DEM) to achieve excellent efficiency at all loads. For example, to boost light load efficiency
• Programmable soft start time to avoid stressing the components when the input power is first applied
• 4.5 to 16V input voltage range
• 0.6 to 5.5V output voltage range
• Remote output voltage sensing to allow you to have the desired voltage at your load. This feature senses the voltage that appears at your load
• Programmable current limit to impose an upper limit on the current for the purpose of protecting the circuit
• Adaptive COT architecture for fast-load transient
• OVP/OTP/OCP/UVP/UVLO protections
• Internal LDO (low dropout) for MOSFET driver bias
• All output ceramic capacitor solution
• Output tracking with external reference input

Using their internal LDOs, these devices are able to operate from a single supply or the designers may resort to an external 3.3V or 5V bias supply if they want to increase conversion efficiency.

TI-2500 Datamath DC-DC converter. Image courtesy of Wikimedia Commons.

SZPL8216A's Applications

These DC/DC buck converters optimise both switching and conduction losses at a high switching frequency and shrink PCB space in PoL applications. They can be used in:

• An industrial DC/DC converter;
• An enterprise server PoL converter; and
• A networking and telecom DC/DC converter

According to Silanna Semiconductor, the sample quantities—together with sample PCBs—are already available through mass production should be starting in the third quarter of 2019.

Ultimately, the new family of synchronous PoL DC/DC buck converters is an excellent addition to Silanna Semiconductor’s line of products. They come in an ultra-compact package, have a 94% efficiency, and have up to 1 MHz switching frequency. This means they can facilitate high power density and efficiency as well as low power loss for demanding applications.