LTC4263 - PSE Controller with Internal Switch
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An Overview study on PSE Controller with Internal Switch
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LTC4263 - PSE Controller with Internal Switch
- 12. DC981 - LTC4263CS/LTC4263CDE Evaluation Kit
- 13. Application: PoE Single Port PSE with the LTC4263 PoE Single Port PSE with the LTC4263
Editor's Notes
- This is a training module for the Linear Technology LTC4263 Power Sourcing Equipment Controller with internal switch
- Welcome to the training module on LTC4263: PSE Controller with Internal Switch. This training module gives you an introduction to Power Over Ethernet technology , PSE features and application information.
- The LTC4263 is an autonomous single-channel PSE controller for use in IEEE 802.3af compliant Power over Ethernet systems. It includes an onboard power MOSFET, internal inrush limit, current limit, and short-circuit control, IEEE 802.3af compliant Powered Device detection , classification circuitry, and selectable AC or DC disconnect sensing. Onboard control algorithms provide complete IEEE 802.3af compliant operation without the need of a microcontroller. The LTC4263 simplifies PSE implementation, needing only a single 48V supply and a small number of passive support components.
- A PSE is required to provide a nominal 48V DC between either the signal pairs or the spare pairs. This device can see more application into networked device equipment which supports POE. It can be used to power up the powered device in networks.
- The device connects to the signal transformers that interface the PSE to the Ethernet cable. It performs detection and classification of the device at the opposite end of the cable, and if this device is a powered device (PD), then 48 V is supplied to its front-end power supply. The front-end supply of the PD then outputs an isolated voltage for use by the main load. Programmable onboard power management circuitry permits multiple LTC4263s to allocate and share power in multi-port systems, allowing maximum utilization of the 48V power supply Built-in foldback and thermal protection provide comprehensive fault protection.
- This page shows the block diagram of the POE. The device that supplies power is called the Power Sourcing Equipment (PSE). A device that draws power from the wire is called a Powered Device (PD). A PSE is typically an Ethernet switch, router, hub, or other network switching equipment that is commonly found in the wiring closets PDs can take many forms. Digital IP telephones, wireless network access points, PDA or notebook computer docking stations, cell phone chargers, and HVAC thermostats are examples of devices that can draw power from the network.
- The LTC4263 autonomously tests for a valid PD connected to the port. It repeatedly queries the port every 580ms, or every 3.2s The LTC4263 checks for the signature resistance by forcing two test currents on the port in sequence and measuring the resulting voltages. It then subtracts the two V-I points to determine the resistive slope while removing voltage offset caused by any series diodes or current offset caused by leakage at the port The LTC4263 will typically accept any PD resistance between 17kΩ and 29.7kΩ as a valid PD. Values outside this range are reported to the user by a code flashed via the LED pin.
- The LTC4263 will classify a port immediately after a successful detection. It measures the PD classification signature current by applying 18V (typ) to the port and measuring the resulting current. The LTC4263 identifies the three IEEE power levels and stores the detected class internally for use by the power management circuitry. In addition, the LTC4263 allows selectable enforcement of IEEE classification power levels.
- The LTC4263 includes a power management feature allowing simple implementation of power management across multiple ports driven by a single power supply. The PWRMGT pins of all LTC4263 devices are tied together along with an RC network to prevent over-allocation of power in a multi-port system. The LTC4263 power management uses pulse width modulation to set the power requirements of each PD. Capacitor CPM is used as a low-pass filter to generate the average power requirement for all PDs in the system. Set CPM to 1μF. For multiple LTC4263s implementing power management, the PWRMGT pins are connected together and to a RC network connected to VSS.
- This page gives an overview on LED driving from a 48V supply. The LED is turned on when the port is connected to a PD and power is applied One fl ash indicates low signature resistance, two fl ashes indicates high resistance, five flashes indicates an overload fault, and nine fl ashes indicates that power management is preventing the port from turning on. The LTC4263 includes a feature for efficiently driving the LED from a 48V power supply without the wasted power caused by having to drop over 45V in a current limit resistor. The modulation frequency of the LED drive is 28kHz, making the on period 2.2μs. During the 2.2μs that the LED pin is pulled low, current ramps up in the inductor, limited by RLED. Diode D2 completes the circuit by allowing current to circulate while the LED pin is open circuit.
- This page gives you a brief introduction to application information like power control, port overload, midspan backup, thermal protection..Etc.
- Demonstration circuits 981A and 981B features the LTC4263 in single port Power Over Ethernet (PoE) Power Sourcing Equipment (PSE) Midspan and Endpoint solutions. DC981 provides two implementations of a PSE controlled by the LTC4263, a Midspan PSE and an Endpoint PSE. A single 48V supply is all that is required to power the board. This in turn provides power to the Midspan PSE and Endpoint PSE outputs. On each solution, an LTC4263 provides detection of a PD, classification, power management, safe power on of the PD, port current limit, and disconnect detection.
- Here we show Typical application block for LTC4263 . LTC4151-1 monitors the isolated 48V power supply to the LTC4263 single port Power Sourcing Equipment (PSE) controller. Communication across isolation through opto-couplers to a microcontroller is simplified with the LTC4151-1’s split bidirectional SDA line to separate data in and data out. Pull-up resistors tie directly to the 48V supply for pins SCL and SDAI, which are internally clamped to 6V, and inverted SDAO is configured to be clamped by an optocoupler diode. With the low speed optocouplers shown, the LTC4263 generating its own 5V supply, and the LTC4151 high voltage protected I2C pins, a separate digital supply is not needed on the PoE side, just the single isolated 48V supply.
- Thank you for taking the time to view this presentation on the “ LTC4263 ” . If you would like to learn more or go on to purchase some of these devices, you may either click on the part list link, or simply call our sales hotline. For more technical information you may either visit the Linear Technology site, or if you would prefer to speak to someone live, please call our hotline number, or even use our ‘live chat’ online facility. You may visit Element 14 e-community to post your questions.