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Method for a backward-compatible fan interface header with a speed control signal

IP.com Disclosure Number: IPCOM000020725D
Publication Date: 2003-Dec-10
Document File: 2 page(s) / 68K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a backward-compatible fan interface header with a speed control signal. Benefits include improved functionality and improved performance.

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Method for a backward-compatible fan interface header with a speed control signal

Disclosed is a method for a backward-compatible fan interface header with a speed control signal. Benefits include improved functionality and improved performance.

Background

         Conventional fan speed control methods use a 3-pin header. The voltage control method has a limited speed range. For example, 12-Volt fans typically do not run at less than 5 or 6 Volts. The voltage control circuit on the motherboard can be expensive. The 3-pin pulse width modulation (PWM) control method chops the power going to the fan. This situation can cause audible noise, is not compatible with some fans, and can cause reduced reliability with fans. Sufficient power may not be provided to the electronics on the fan, and the speed range of the fan can be limited.

         Full fan current must pass through a transistor. Higher current requires a more expensive transistor. Higher current fans can be incompatible with circuits that implement a lower-current-capable transistor.

Description

         The disclosed method is a fan header that adds a fourth pin to enable speed control of the fan. This pin enables speed control to be separate from power delivery, enabling the fan to always be powered sufficiently, regardless of the required fan speed.

         The disclosed method provides backward compatibility with 3-pin fans due to the unique keying. Four-pin headers have a wider key that is centered and not offset (see Figure 1).

         The disclosed metho...