Overview
The LM5070MTCX-80/NOPB, produced by Texas Instruments, is an integrated Power over Ethernet (PoE) PD interface and PWM controller. This device provides a comprehensive solution for Powered Devices (PD) that connect into PoE systems, ensuring full compliance with the IEEE 802.3af standard. The LM5070 integrates an 80V, 1Ω, 400mA internal MOSFET switch and associated control, along with a current mode PWM controller for dc-dc converter topologies. It supports both isolated and non-isolated applications and includes features such as programmable inrush current limit, thermal shutdown protection, and soft-start functionality.
Key Specifications
| Parameter | Min | Typ | Max | Units |
|---|---|---|---|---|
| Default Current Limit | 325 | 390 | 420 | mA |
| Oscillator Frequency (RT = 30.3kΩ) | 175 | 200 | 225 | kHz |
| Oscillator Frequency (RT = 10.5kΩ) | 505 | 580 | 665 | kHz |
| Max Duty Cycle (-80 Device) | 80% | |||
| Max Duty Cycle (-50 Device) | 50% | |||
| Thermal Shutdown Temperature | 165°C | |||
| Package Type | TSSOP-16 |
Key Features
- Fully compliant with IEEE 802.3af Power Interface Port
- 80V, 1Ω, 400mA internal MOSFET switch
- Programmable inrush current limit (75mA to 390mA)
- Programmable under-voltage lockout with hysteresis
- Thermal shutdown protection
- Current mode PWM controller with slope compensation (for -80 device)
- Supports both isolated and non-isolated applications
- Soft-start functionality to reduce start-up stresses
- Error amplifier and reference for non-isolated applications
- Programmable oscillator frequency
Applications
The LM5070 is designed for use in various Power over Ethernet (PoE) systems, including but not limited to:
- Network devices such as switches, routers, and access points
- IP phones and other VoIP equipment
- Wireless access points and security cameras
- Industrial control systems and automation devices
- Any device requiring power delivery over Ethernet cables
Q & A
- What is the primary function of the LM5070?
The LM5070 is an integrated Power over Ethernet (PoE) PD interface and PWM controller, providing a complete solution for Powered Devices (PD) in PoE systems.
- What is the maximum duty cycle for the LM5070-80 device?
The maximum duty cycle for the LM5070-80 device is 80%.
- How is the oscillator frequency programmed in the LM5070?
The oscillator frequency is programmed by a single external resistor connected between the RT and ARTN pins.
- What is the purpose of the soft-start feature in the LM5070?
The soft-start feature allows the power converter to gradually reach the initial steady state operating point, reducing start-up stresses, output overshoot, and current surges.
- Does the LM5070 support both isolated and non-isolated applications?
- What is the thermal shutdown temperature of the LM5070?
The thermal shutdown temperature of the LM5070 is 165°C.
- How is the inrush current limit programmed in the LM5070?
The inrush current limit can be programmed using a resistor at the RCLP pin, with a range from 75mA to 390mA.
- What is the role of the error amplifier in the LM5070?
The error amplifier is used for loop compensation and is configured as an open drain output, with a fixed reference voltage of 1.25V.
- Does the LM5070 have slope compensation for current mode control?
- What package types are available for the LM5070?
The LM5070 is available in TSSOP-16 and WSON-16 (5 mm x 5 mm) packages.
