Overview

Programmable AT Fuse is an electronic fuse for protecting AT PC hardware from potentially damaging events such as over current and over voltage. Programmable AT fuse includes programmable current limit for the two main power rails – the 5V and the 12V – with 250mA increments, allowing the user to set the current with high accuracy.

Programmable AT Fuse also includes voltage comparator with configurable window size where voltage is allowed to drift within the set window, but when the voltage drifts outside the window – such as in an over voltage situation – power is cut immediately.

Average reaction time under 200 microseconds.

The Programmable AT Fuse includes integrated -5V linear regulator for making the output power fully compatible with the older AT standard. Input to the Programmable Fuse is ATX, i.e. a modern power supply with superior capabilities; also lets you upgrade your old hardware to use modern power supply!

Programmable AT Fuse is fully self-contained with wide range of additional features and with simple and intuitive graphical configuration system.

Three separate profiles for storing configuration parameters for three separate systems for convenient way to recall different configurations.

Features

• Fully self-contained
  • Configurable through buttons and on-board interface
• Over-current protection with 250mA steps for 5V and 12V
  • 0-10A for 5V
  • 0-5A for 12V
• Voltage tolerance window (±% off the nominal)
  • 5V, 12V, -12V and -5V
  • 25% maximum window size to both directions (0-50% total window size)
• Physical fuses
  • 10A for 5V
  • 5A for 12V
  • 315mA for combined -12V and -5V
• Sub-200µs response time to current and voltage situations
• Support for both momentary and latching power switch
• Configurable start-up delay for in-rush current (0-65ms)
• Pulse pass feature
  • Let bursts of current/voltage pass without triggering protection
  • Configurable pulse length (0-65ms) and pulse magnitude (100-250% above nominal set value)
• Support for 3 profiles each with separate configured values
• Configurable over temperature protection for the device itself (60°C – 125°C)
• Acrylic back plate to protect from short circuit
• Information display while powered on
  • Current displays for 5V and 12V
  • Voltage displays for 5V, 12V, -12V and -5V
  • Power displays for 5V, 12V and 5V + 12V total power
• High contrast OLED display
• Three ways to turn on the power
  • on-board button
  • on-board 2-pin header
  • power switch connected to ATX-AT adapter cable
• Integrated -5V regulator
  • Adds the -5V missing in ATX power supplies
• Maximum recommended power 80W
  • Over-temperature protection

Compatibility

Compatible with motherboards with AT style P8/P9 power connector.

Not compatible with ATX! Attempting to plug into an ATX motherboard may result in damage to the device and/or to the motherboard and anything connected to the motherboard.

Notes

Who is it for?

It is recommended that the user has some electronics experience, as while this device protects against short circuit and over voltage, one still needs to diagnose the problem when one suspects there is a problem. This device is a tool for protection and detection of problems; not fix to a problem.

On ATX power supply selection

It is recommended to use modern ATX power supply (2010 or newer). Select a power supply with emphasis on +5V rail; other power rails are more or less irrelevant. However, all +5V, +12V and -12V are required.

Manual

Comes with lengthy, descriptive manual on how to configure the device, and how to respond to trigger events (over current, over voltage, under voltage).

ATX-AT Cable

You need an ATX-AT adapter cable to connect the fuse to the motherboard. These are available from the usual sources, or you can choose to include one for additional price. I have two version: standard and modified. Modified comes with longer power switch leads and is better suited for permanent installations. Both are electrically identical.