Single unit integrated transformer assembly

A transformer unit includes a first isolation transformer, a second isolation transformer and a power transformer. A single package incorporates the first isolation transformer, the second isolation transformer and the power transformer. A plurality of connection pins provide connections to the first isolation transformer, to the second isolation transformer and to the power transformer. A process is also provided for connecting transmission lines to a network device including providing transmission lines carrying an electrical supply current, sufficient to power the network device, concurrently with a network data signal. The single unit has the first integrated isolation transformer the second integrated isolation transformer and the power transformer. Some of the transmission lines are connected to the first isolation transformer to isolate transmission signals on the sending transmission lines from a transmitter of the network device. Some other transmission lines are connected to the second isolation transformer to isolate transmission signals on the receiving transmission lines from a receiver of the device. Within the single unit each of the first isolation transformer and the second isolation transformer are connected to the power transformer. The power transformer is used to supply power to the circuit board of the network devise at a potential which is reduced compared to a potential of said transmission lines carrying the electrical supply current.

FIELD OF THE INVENTION

The invention relates generally to the field of transformers and more particularly to transformer applications requiring multiple transformer functions.

BACKGROUND OF THE INVENTION

Transformers are used extensively for various different purposes. A well-known transformer use is to change voltage levels between a voltage supplied and a voltage to be used by an electronic device. Such a transformer is typically a core with a winding. Transformers for power applications of course vary and include transformers for high voltage applications and transformers for relatively low voltage applications.

Transformers are also used extensively for signal applications. Communications applications often use signal transformers. Such a signal transformer is used at low voltage levels for isolating a transceiver from the communications medium. This will be for example an Ethernet isolation transformer used to separate the transmitter and receiver of an Ethernet card or similar device (e.g., network interface card for NIC).

Ethernet isolation transformers are typically provided as a small package mounted on the Ethernet printed circuit board. The transformer has its connections appropriately connected to contacts on the board. The Ethernet isolation transformers (e.g., for IEEE 802.3 applications) are typically provided with very small windings and a very small ferrite core. The structure is provided with a plastic package and digital interface pins (e.g., 16 pins). The entire structure may be, for example, in. to inch.

The IEEE 802.3 standard (ETHERNET) has no current provisions for supplying power to Ethernet devices. One proposal for supplying power is to provide the power on the Ethernet connection, namely the transmission medium. The issues as to supplying power involve issues as to the environment of the system as well as in the overall costs.

Providing power locally presents problems for Ethernet applications. One example of a problem encountered is the security camera problem wherein the local supply of power can be problematic as to the secure status of such a security camera. A possible solution is to provide the transmission medium as a medium for supplying power (the Ethernet wire is used for supplying power). However, this involves some problems as well.

Another network device which has been increasingly used in network environments is a network phone. Such a phone device converts audio analog signals into digital signals and sends the digital signals out in the form of packets over a network such as a local area network ( LAN). The phone devices can be provided with a power circuit which is integrated into the phone. The AC power is applied to the phone and the power is conditioned (e.g., rectified) and possibly also converted by a transformer.

A changeover from the approach of supplying power locally to a system involving supplying power via the network wires involves various problems including the need to condition the power supplied over the wire. One significant problem is the need to supply the power over the network wires at a relatively high voltage level. For example, the use of 45 volts AC or greater voltage over the wire is considered to be advantageous. However, the use of high voltage levels results in higher cost with regard to semiconductor devices used in the network device. Typically, voltage levels below 30 volts are desirable with regard to maintaining semiconductor unit costs at a low level. Semiconductor devices which use higher voltage levels typically result in higher costs.

SUMMARY AND OBJECTS OF THE INVENTION

It is an object of the invention to provide a transformer unit with a single package having an integrated signal transformer and power transformer.

It is another object of the invention to provide a transformer unit with a single package which can be mounted on a circuit board of a network device and which can connect to network wires which wires carry a signal with a power component and a communications signal component and which transformer unit transforms the signal to provide a power signal at a lower voltage value and which transformer unit isolates the network transceiver of the circuit board from the signal carried by the wires.

It is a further object of the invention to provide a unit with input connections which are connected to a transmission media and output connections which are to be connected to a communications printed circuit board (PCB) and which cooperates with the PCB to form a network device and which unit includes a signal transformer and a power transformer and the transmission media carries both a power signal to power the network device and carries communications signals to and from the network device.

According to invention, a transformer unit is provided including and isolation transformer and a power transformer. The isolation transformer and the power transformer are provided as part of a single package or within a single housing having a plurality of connection pins. The connection pins include Ethernet wire connection pins connecting to e.g. 45 volts AC wires. The wires may be the typical Ethernet Tx , Tx , Rx , Rx lines. However, the transformer unit is preferably used wherein the wires carry a 60 Hz 48 V AC signal (60 Hz ISO 48 V poential) between the Tx and Tx and the Rx and Rx . In addition, the Tx and Tx have a series superimposed plus 2V pulse. The Rx and Rx have a series superimposed plus 2V pulse. Additionally, the connection pins of the transformer unit include transformer output pins providing 12 volts AC to the circuit board of the network device. Additional output pins are provided including Tx , Tx , Rx and Rx , which signals are isolated by the isolation transformer portion of the transformer unit.

The unit preferably includes a power transformer portion including a core and a winding with two isolation transformers each including a core and windings. The isolation transformers each include a center tap, which may be used to eliminate noise (electromagnetic interference).

It is still another object of the invention to provide a process for connecting transmission lines carrying a power signal component and a transmission signal component to a network device which uses the power supplied by the network transmission lines.

According to a further aspect of the invention, a process is provided for connecting a network device, including providing a single unit with integrated isolation transformers and power transformer. The unit is connected to 4 transmission lines carrying a network signal and power signal (a signal with a power component and with a network communications signal component). A first isolation transformer in the unit isolates transmission signals on the sending transmission lines from a transmitter of the device. A second isolation transformer in the unit isolates transmission signals on the receiving transmission lines from a receiver of the device. Each of the first isolation transformer and second isolation transformer are connected to the power transformer, which supplies power to the circuit board of the device.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings in particular, the invention comprises a single unit integrated transformer assembly generally designated 10 as shown in FIG. 1 . The unit 10 includes a first isolation transformer 20 , a second isolation transformer 30 and power transformer 40 provided integrated within a single package 12 .

The first isolation transformer 20 includes a ferrite core 21 and windings 23 and 25 . Transformer 20 has a first input connection 22 and second input connection 24 . The first input connection 22 and second input connection 24 are provided at ends of the winding 23 . First isolation transformer 20 has a first output connection 26 and second output connection 28 at ends of coil 25 as well as a center tap 27 connected at the center of the coil 25 . A center tap 29 is connected to the first coil 23 .

The second isolation transformer 30 includes a ferrite core 31 and windings 33 and 35 . Transformer 30 has a first input connection 32 and second input connection 34 . The first input connection 32 and the second input connection 34 are provided an ends of the winding 33 . Transformer 30 has a first output connection 36 and second output connection 38 connected to ends of coil 35 as well as a center tap 37 connected at the center of the coil 35 . A center tap 39 is connected to the first coil 33 .

The power transformer 40 includes a core 41 with windings 43 and 45 . Winding 45 is connected at 42 to the center tap 29 of the first isolation transformer 20 . Winding 45 is connected at 44 to the center tap 39 of the second isolation transformer 30 . Coil 43 provides two output connections 46 and 48 .

As shown in FIG. 2 , the single unit integrated transformer assembly 10 is advantageously used with a network connection providing the network communications signal as well as the power signal. That is, a signal is provided over the network lines 50 , 52 , 54 and 56 which includes both a power component as well as the signal component. The line 50 is the transmission plus line or Tx line, the line 52 is the transmission minus line or Tx line, the line 54 is receiving plus line or Rx line and the line 56 is the receiving minus line or Rx line. Looking at lines 50 and 52 , the lines have a 60 Hz AC signal with a 48 volt potential. Series superimposed on this, on the Tx line and Tx line, is a 2V pulse signal. Looking at lines 54 and 56 , the lines have a 60 Hz AC signal with 48 volt potential. Series superimposed on this, on the Tx line and Tx line, is a 2V pulse signal. The first isolation transformer 20 provides an isolated signal at output connections 26 and 28 as well as a center tap signal at 27 , used to eliminate noise (EMI). The second isolation transformer 30 provides an isolated signal at the output connections 36 and 38 as well as a center tap signal at 37 , used to eliminate noise (EMI).

The power transformer 40 is provided with a signal from the Tx lines and the Rx lines at 29 and 39 respectively. The transformer 40 transforms the 48 volt AC signal to a 12 volt AC signal, which is sent to the circuit board at 60 and 62 .

The process of the invention includes providing the single unit 10 with integrated first isolation transformer 20 , second isolation transformer 30 and power transformer 40 provided as THE integrated transformer assembly unit 10 . First and second Ethernet transmission lines 50 and 52 are provided which carry a signal including a 60 Hz ISO 48V potential component and a series superimposed communication pulse (e.g. / 2V) component. Similarly, first and second Ethernet receiving lines 54 and 56 are provided which carry a signal including a 60 Hz ISO 48V potential component and a series superimposed coumiunication pulse (e.g. / 2V) component. Line 50 is connected to contact 22 , line 52 is connected to contact 24 , line 54 is connected to contact 32 and line 56 is connected to contact 34 . The contacts 22 , 24 , 32 and 34 are provided as pins 8 shown in FIG. 3 . The pins 8 are connected by the printed circuit board to the lines 50 , 52 , 54 and 56 . The unit 10 has further pins 8 including output contacts, namely contacts 26 , 27 , 28 , 36 , 37 and 38 . Contacts 26 and 28 are connected, such as via an appropriate filter, to a transmitter formed on the printed circuit board of the network device. Contacts 36 and 38 are connected, such as via an appropriate filter, to a receiver formed on the print circuit board of the network device. Center taps 29 and 39 at the network wire side of each of the isolation transformers are connected to the power transformer 40 . The power transformer 40 has output connections 46 and 48 connected to circuit board connections 60 and 62 . With this arrangement, 12 volt AC power is provided via the power transformer 40 to the circuit board of the network device.

This allows the electrical supply current, sufficient to power an access point (a network device), to be transmitted concurrently with a network data signal across a transmission line wherein a single unit is provided for the network device transformer functions. A power and data coupler may also be used that couples the network data signal and the power signal, received through a data input and a power input respectively, and transmits the coupled signal, to a distance of three meters or more, over the transmission line to a power and data decoupler. The power and data decoupler separates the power signal from the network data signal and supplies those signals to a power output port and a data output port, respectively, for use by a wireless access node. The power signal may be modulated at a low frequency relative to the frequency of the data signal, and the network data signal has a data transmission rate of one megabit/second or higher.