Murata Augments its Line Power Over Ethernet (POE) DC/DC Converters

Ethernet-based devices need to handle an ever-increasing amount of data and to achieve bidirectional data transfer at faster and faster speeds. These remote units require significant electrical power to accomplish these tasks, and the MYBSP01206AZFT makes it possible to glean that power from the LAN cable itself, obviating the need for separate power cabling.

The MYBSP01206AZFT. Image courtesy of Murata

The MYBSP01206AZFT is Murata’s latest addition to its MYBSP line of DC/DC converters, providing DC power to remote Ethernet devices, often referred to as powered devices (PD). The unit switches at a fixed frequency of 410 kHz, making possible a typical efficiency of 93.2% at full load. With little waste heat generated, there is no need for a heat sink.

The MYBSP01206AZFT operates over an input range of 41.1 to 57 VDC, conforming to the IEEE 802.3af standard of 44 to 57 VDC for power sourcing equipment (PSE). Line and load regulation are both specced at ±0.1%.

 

The Operation of the MYBSP01206AZFT

Unshielded twisted-pair cables (UTP) are frequently used as Ethernet cables. They can carry power as well as bidirectional data.  As indicated in the diagram below, the power is separated from the data and is processed by the DC/DC converter to a steady 12 volts.

Simplified block diagram for the MYBSP01206AZFT. Image courtesy of datasheet

As illustrated, there is optional support for PSE-type indicators and for adapter ORing. Isolation capacitance is 1500 pF.

 

Protections

These include protections for:

• Overtemperature protection
• Output overvoltage
• Input overvoltage lockout
• Output current, employing hiccup mode auto restart

 

Absolute Maximums

The device provides 2250 VDC input to output isolation. The maximum continuous voltage is 57 VDC, but the unit can tolerate a 60 VDC transient for a maximum of 100 ms.

 

Input Specifications

• Startup threshold for rising voltage, minimum and maximums, are 36.1 and 40.2 VDC, respectively
• Under-voltage shutdowns for falling input voltage are 30.3 and 33.8 VDC, minimum and maximum
• The full load input current is 1.61 amps
• No-load input current is 54 mA

 

Output Specifics

• The output voltage, under all conditions, is 11.64 VDC minimum and 12.36 VDC maximum
• Over voltage protection kicks in at 14.4 VDC
• Ripple and noise is 100 mV peak-to-peak (typical)

 

Dynamic Characteristics

• The output voltage rise time, from 10% to 90% of VOUT, is typically 1 ms.
• For a 50-100-50% load step to 1% of Vout 

                   ○Dynamic load response is typically 1 µsec

                   ○Dynamic load peak deviation is typically ±150 mVDC

 

Applications

Murata cautions that the MYBSP01206AZFT may not be suitable for applications such as medical equipment and similar uses, and the company encourages consultation in such cases. However, the device is targeted at: 

• IoT gateways for edge computing
• Smart lighting
• High-resolution camera modules 
• Point of sale (POS) devices

 

Physical Specifications

• The dimensions of the MYBSP01206AZFT are 56.4 x 22.2 x 8.52 mm
• The unit’s typical weight is 20.8 grams
• The device operates over a temperature range of -40 to 85℃