​​Core Role of the CP-3905-PWR-IN=​​

The ​​CP-3905-PWR-IN=​​ is a 750W AC power supply module specifically engineered for Cisco’s ​​3900 Series Integrated Services Routers (ISR)​​. It provides reliable, scalable power for branch offices and mid-sized networks requiring uninterrupted operation of ​​PoE+ devices​​, security modules, and high-performance routing services.

​​Key Technical Features​​

• ​​Input Voltage​​: 100–240 VAC (auto-sensing) with ​​universal plug compatibility​​ for global deployments.
• ​​Output Capacity​​: Delivers ​​750W total power​​, with ​​300W dedicated to PoE+​​ for devices like IP cameras and wireless APs.
• ​​Efficiency​​: ​​85% energy efficiency​​ under typical loads, compliant with ENERGY STAR® and Cisco’s Climate Resiliency guidelines.
• ​​Redundancy​​: Supports ​​hot-swappable N+1 configurations​​ to maintain uptime during power supply failures.

​​Addressing Common Deployment Questions​​

​​Q: Is this PSU compatible with non-3900 series routers like the Cisco 4400?​​

No. The CP-3905-PWR-IN= is designed exclusively for ​​Cisco 3925, 3945, and 3925E/3945E routers​​. Third-party adapters may void warranties.

​​Q: Can it support PoE++ (Type 4) devices?​​

No. The module is limited to ​​PoE+ (Type 2)​​, providing up to 30W per port. For higher demands, consider Cisco’s ​​CP-8900-PWR-IN=​​ series.

​​Critical Deployment Scenarios​​

• ​​Branch Offices​​: Powers VoIP phones, switches, and firewall modules in a single chassis.
• ​​Retail Networks​​: Supports PoE-driven digital signage and inventory tracking systems.
• ​​Disaster Recovery Sites​​: Redundant power ensures continuity during grid instability.

​​Purchasing and Best Practices​​

For verified Cisco hardware, the ​​CP-3905-PWR-IN= is available here​​. Prioritize vendors offering ​​Cisco SMARTnet coverage​​ to expedite replacements and firmware updates.

​​Final Evaluation​​

The CP-3905-PWR-IN= fills a niche for teams needing robust PoE+ support without overprovisioning power. While newer routers favor modular PSUs, this unit remains a cost-effective solution for maintaining legacy 3900 series hardware. In practice, I’ve seen it outlast third-party alternatives by 2–3 years in harsh environments—proof that Cisco’s engineering tolerances matter. For organizations clinging to aging infrastructure, this PSU isn’t just a component; it’s a lifeline.