Berg connector
A Berg connector is a compact, 4-pin electrical connector originally developed by Berg Electronics Corporation for powering 3.5-inch floppy disk drives in personal computers.[1] It features a keyed design with a 2.5 mm pitch, square pins measuring 0.64 mm, and delivers +5 V DC (red wire) and +12 V DC (yellow wire) power alongside two ground connections (black wires), preventing incorrect insertion and ensuring reliable low-current supply to peripherals.[2][3] Founded in 1950 in St. Louis, Missouri, Berg Electronics specialized in miniature interconnects; the company was acquired by DuPont in 1972, sold by DuPont in 1993, acquired by FCI in 1998, and FCI (including Berg) was acquired by Amphenol in 2016. TE Connectivity (formerly AMP) continues to produce compatible parts under designations like the AMP EI Series (e.g., cable socket 171822-4).[2] Introduced in the 1980s alongside the rise of IBM PC-compatible systems and insulation displacement contact (IDC) technologies, the Berg connector became a de facto standard for internal power distribution in early computing hardware, including connections from power supply units to floppy drives, front-panel indicators, and other low-power components.[3] While variants exist, such as 2-pin versions for simpler tasks like LED or switch connections, the 4-pin floppy power type remains the most iconic, often daisy-chained in cables for multiple devices.[3][4] Though largely obsolete in modern systems favoring SATA or Molex Mini-Fit Jr. connectors for higher power needs, Berg connectors persist in legacy computing, retro builds, and niche applications like Amiga or vintage PC restorations due to their durability and ease of crimping with 22 AWG wire.[5][6] Their design emphasizes cost-effective, vibration-resistant mating for through-hole or surface-mount PCB integration, but users must inspect for bent pins or wear from repeated connections.[5]Introduction
Definition and Physical Characteristics
The Berg connector is a brand of electrical connector developed by Berg Electronics Corporation, most notably the 4-pin variant used in computer hardware for powering peripherals such as 3.5-inch floppy disk drives, though the term often refers more broadly to the company's line of compact interconnects for power and signal applications.[7] While the broader family includes pin headers known as BergStik, the iconic 4-pin power type features a keyed, polarized design with a 2.54 mm (0.100 in) pitch and square pins measuring 0.64 mm (0.025 in) on each side.[8] This 4-pin configuration delivers +5 V DC and +12 V DC power with two ground connections, ensuring prevention of incorrect insertion. The housing incorporates alignment keys to maintain proper orientation, and the design supports low-current supply to peripherals. The housing is typically made from durable nylon or high-temperature thermoplastic for insulation and stability, with contacts of phosphor bronze for conductivity. Corrosion resistance is provided by plating such as gold or tin over nickel.[8][9]Historical Development
Berg Electronics, founded in 1950, developed a range of miniature connectors in the mid-20th century, including the PV contact system that formed the basis for later products. The specific 4-pin Berg connector for floppy drives emerged in the 1980s as a compact alternative to larger Molex connectors for smaller PC peripherals.[10] A key milestone came in the mid-1980s, around 1986, with the adoption of the 4-pin configuration for 3.5-inch floppy drives in IBM-compatible systems, such as the IBM PC Convertible, enhancing compatibility with evolving PC standards.[11][12] By the mid-1980s, the 4-pin Berg had earned widespread recognition in industry parlance due to its reliability in personal computing applications.[13]Floppy Drive Power Connector
Design Specifications
The Berg connector for floppy drive power delivery features a compact 4-pin linear polarized form factor, commonly designated as LP4, designed to provide efficient space utilization in drive enclosures. This configuration employs a 2.5 mm pitch between pins, resulting in overall dimensions of approximately 14 mm in length, 5.8 mm in width, and 5.75 mm in height, enabling reliable mating with corresponding PCB headers in constrained environments.[14][15][16] The housing is constructed from white nylon 6/6 material, which offers durability and flame retardancy compliant with UL 94V-2 standards, ensuring mechanical stability under typical operating conditions. It adopts a latchless design that relies on a friction lock mechanism for secure mating, preventing accidental disconnection while allowing easy installation and removal. This housing is compatible with 20 AWG wire gauge, accommodating the stranded conductors commonly used in power cables for adequate current handling without excessive heat buildup.[14] Contact specifications include a female receptacle configuration utilizing crimp termination, though variants support IDC termination for integration with flat ribbon cables, facilitating straightforward assembly in mass-produced drive systems. Each contact is rated for 3 A per pin, supporting the power demands of floppy drives, with an operating temperature range up to 105°C to withstand internal chassis heat.[17][18][19] While the EI series offers variants in shrouded and unshrouded configurations for different applications, the standard implementation for floppy drives employs an unshrouded receptacle to minimize footprint and height in space-constrained 3.5-inch drive bays, enhancing compatibility with low-profile PCB layouts. This design draws from the broader Berg connector family's 2.5 mm pitch baseline, ensuring interoperability with standard headers while optimizing for power-specific needs.[20][21]Pinout and Electrical Ratings
The standard pinout for the 4-pin Berg connector used in floppy drive power applications follows the ATX specification, providing +5 VDC on pin 1 for drive logic and +12 VDC on pin 4 primarily for legacy stepper motor operation in certain drive models, with two ground connections on pins 2 and 3 to reduce electrical noise and ensure stable operation.[22] Wire colors adhere to ATX power supply conventions, using red for +5 VDC, black for ground, and yellow for +12 VDC.[22]| Pin | Signal | Color | Purpose |
|---|---|---|---|
| 1 | +5 VDC | Red | Drive logic power |
| 2 | Ground | Black | Common ground |
| 3 | Ground | Black | Common ground (noise reduction) |
| 4 | +12 VDC | Yellow | Stepper motor power (where applicable) |