Molex connector
Molex connector is the vernacular term for a two-piece pin and socket interconnection, most frequently disk drive connectors. Pioneered by Molex Incorporated, the two-piece design became an early electronic standard. Molex® developed and patented the first examples of this connector style in the late 1950s and early 1960s. First used in home appliances, other industries soon began designing it into their products from automobiles to vending machines to mini-computers.
In such a connector, cylindrical spring-metal pins fit into cylindrical spring-metal sockets. The pins and sockets are held in a rectangular matrix in a nylon shell. The connector typically has 2, 3, 4, 5, 6, 9, 12, or 15 circuits. Pins and sockets can be arranged in any combination in a single connector, and each housing can be either male or female.
There are three typical pin sizes: 1.57 mm (0.062 in), 2.36 mm (0.093 in), and 2.13 mm (0.084 in). The 1.57 mm pin can carry 5 A of current, while the 2.36 mm can carry 8.5 A. Because the pins have a large contact surface area and fit tightly, these connectors are typically used for power.
This style of connector was first used as a computer disk drive connector in the late 1970s, initially on the Shugart floppy disk drive as well as Atari (1979) on its path to becoming a de facto standard. It is in this role, that the vernacular term molex connector is most frequently used. This interconnection configuration was the established standard for disk drive power connectors until the advent of SATA disk drives.
Desktop PC use
Several types of pin and socket connectors have become established for power connections in desktop PCs, because of the simplicity and reliability of the design. Certain Molex connectors are used for providing power to the motherboard, fans, and floppy disk drives; and hundreds of others.
In practice, compatible connectors are available from a myriad of manufacturers.
Motherboard power connector (Molex Mini-Fit Jr.™)
In 20/24 pin configurations, the Mini-Fit Jr.™ connector may be used on ATX motherboards as the main power connector. 4, 6 and 8 pin configurations of the same style of connector are used for additional CPU power and graphics card power. This is changing as power, signal and speed requirements increase in sophistication and electronic requirements. More commonly, the Mini-Fit Jr.™. can be found in consumer applications, such as white goods, requiring high density and high current.
These connectors are polarised so that they cannot be inserted incorrectly, and lock into position using a latch.
Standard pinout: Template:ATX power connector
Power good goes high to indicate that voltages are stabilised and ready for use. Power on is internally driven high, and shorting this pin to ground will turn on the power supply.
Disk drive connector (Molex 8981 Disk Drive Power Connection System)
 | |||
| Type | Electrical power connector | ||
|---|---|---|---|
| Production history | |||
| Designer | Molex | ||
| General specifications | |||
| Width | 21 mm | ||
| Height | 6 mm | ||
| Pins | 4 | ||
| Electrical | |||
| Signal | Yes | ||
| Max. voltage | 12 V | ||
| Max. current | 11 A/pin (30 °C rise) | ||
| Pinout | |||
| Pin | Color | Type | |
| Pin 1 | Yellow | +12 V | |
| Pin 2 | Black | Ground | |
| Pin 3 | Black | Ground | |
| Pin 4 | Red | +5 V | |
| 18 AWG wire is typically used. | |||
The desktop computer hard-drive connector is pictured here. It has 4 circuits, with the standard pinout as follows:
| Pin # | Color | Function | |
|---|---|---|---|
| 1 | Yellow | +12 V | |
| 2 | Black | Ground | |
| 3 | Black | Ground | |
| 4 | Red | +5 V | |
Sometimes, especially in older computers, the colors differ. The pins are 0.200 in (5.1 mm) apart (center to center). The connector housing has chamfered corners on one side to prevent the user from plugging it in incorrectly. The connector that provides power (e.g., on a power supply) has female pins and a male housing; the connector that receives power (e.g., on a peripheral) has male pins and a female housing.
The connector is standard on all PATA disk drives and low-end SCSI disk drives; however, newer disk drives will employ a more advanced integrated serial interconnection. These new, advanced connection systems are being developed by Molex and other connector companies, often working together to develop interconnection standards.
Despite its widespread adoption, the connector has problems as a 30-year-old product. It is cumbersome and difficult to remove because it is held in place by friction instead of a latch. It is specific to this one application, so it is not as widely available as most electronic connectors, and is more expensive.
See also
- Berg connector
- Molex (company)