National Semiconductor LM5071 Power over Ethernet PD Controller with Auxiliary Power Interface Data Sheet
Summary
The LM5071 is a highly integrated PWM controller designed for robust power management in Powered Devices (PDs) utilizing Power over Ethernet (PoE). This essential chip supports complex power sourcing by accepting both standard IEEE 802.3af PoE and dedicated auxiliary DC/AC inputs. The accompanying technical documentation provides comprehensive details on critical features, including programmable classification, under-voltage lockout (UVLO), soft-start control, and current limiting for reliable system operation. It is the ideal component solution for electrical engineers developing next-generation intelligent devices that require flexible and high-reliability power interfaces.
Manual Details
| Brand | National |
|---|---|
| Pages | 18 |
| File Size | 844.11 KB |
| Published | June 15, 2026 |
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Frequently Asked Questions
How does the LM5071 manage startup if auxiliary power is used?
Connecting an ac adapter to the Auxiliary Power Enable Pin activates the PWM controller, enabling PD power when PoE network power is unavailable.
What are the different duty cycle limits available for this device?
The IC is available with options providing 50% or 80% Maximum Duty Cycle Limit.
Is the LM5071 compatible with both isolated and non-isolated applications?
Yes, the LM5071 supports both Isolated and Non-Isolated Applications for powered devices (PD).
How must signature detection be implemented on the device?
Signature detection requires connecting a resistor from V to pin 2 (RSIG).