6.7 12 V DC power (PWR-DC12)

PWR-DC12 is the power domain of nominal 12 V DC, and an optional feature for the products in it: a module with a rear DC entry, a DC entry panel or a bus board with PWR-DC12 outlets that feeds several modules from one entry, a case DC entry on an enclosure, a power supply that takes 12 V DC and delivers the bus, and the cables between them. The 12 V DC comes from an external adapter, the domain's source, enters at a DC entry, and feeds a DC rail, one +V and −V pair that each product filters or regulates locally (Terms). The DC rail is separate from the bus (6.4); the rules common to both domains are in 6.1 to 6.3.

Filtering, output connectors, ripple at PWR-DC12 outlets, and the adapter a product ships with are product documentation, not EIS. The connection rules for the person fitting it are in 9.3. The tables are in data/dc_12.json.

DC entries

A product shall publish its DC entry variant: DC-BAR21, DC-BAR25, DC-VH2, DC-DIN4, DC-MF6, or DC-MF8 (DC-001), and the minimum and maximum DC input voltage its DC entry accepts (DC-002). Two kinds of DC entry share the domain. A module DC entry, DC-BAR21 or DC-VH2, takes the rail for one module from a PWR-DC12 outlet. A case DC entry, DC-BAR25, DC-DIN4, DC-MF6, or DC-MF8, takes a brick's output for a row: it sits on an enclosure, which then claims PWR-DC12-IN, or on a DC entry panel, a module that claims PWR-DC12-IN and feeds the supply, the bus board, or its own PWR-DC12 outlets, for which it claims PWR-DC12-OUT too. The wires from a case DC entry to what it feeds are row wiring (6.1). A DC entry shall be marked beside it with its polarity symbol, its nominal voltage, and its maximum current (DC-011), as the trade marks every DC inlet. The current it takes at its DC entry, or delivers at each distribution output, is published at 12 V like every domain's (PWR-001, PWR-002). A DC entry shall not use the pinout of a Eurorack 10-pin or 16-pin power header (DC-003).

A barrel DC entry, DC-BAR21 or DC-BAR25, shall be center positive (DC-004).

Variant Pin × barrel (mm) Typical continuous (A) Notes
DC-BAR21 2.1 × 5.5 2.5 Also a PWR-DC12 outlet to a module (DC-009).
DC-BAR25 2.5 × 5.5 5 Higher current, from an adapter; never an output to a module (DC-009). A DC-BAR25 plug enters a DC-BAR21 DC entry but makes unreliable contact (ASM-004).

DC-VH2 is a 2-pin JST VH wire-to-board header, rated 10 A, that takes power from a PWR-DC12 outlet. Above 5 A, EIS recommends DC-VH2, DC-DIN4, DC-MF6, or DC-MF8 rather than a barrel: a through-hole 2.1 mm jack is rated about 2.5 A and a 2.5 mm jack about 5 A, and the product publishes its own figure (PWR-001). A product with a DC-VH2, DC-DIN4, DC-MF6, or DC-MF8 DC entry shall implement the pin functions tabulated for that variant (DC-005). The receptacle and plug named are reference parts; an interchangeable part rated for the published current may be used.

Variant Receptacle (reference) Mating plug (reference) Rated continuous (A) Rating basis
DC-VH2 JST B2P-VH or B2PS-VH JST VHR-2N 10 1 contact per pole × 10 A (JST VH)
DC-DIN4 Kycon KPJX-4S-S Kycon KPPX-4P 15 2 contacts per pole × 7.5 A (Kycon KPJX-4S-S)
DC-MF6 Molex 39-30-1060 Molex 39-01-2060 24 3 circuits per pole × 8 A at 18 AWG (Molex PS-5556-001, 4 to 6 circuits)
DC-MF8 Molex 39-30-1080 Molex 39-01-2080 28 4 circuits per pole × 7 A at 18 AWG (Molex PS-5556-001, 7 to 10 circuits)

DC-VH2 pins

Pin Function
1 +V
2 −V

DC-DIN4 pins

Pin Function
1 +V
2 −V
3 −V
4 +V
5 shell (optional)

DC-MF6 pins

Pin Function
1 +V
2 +V
3 +V
4 −V
5 −V
6 −V

DC-MF8 pins

Pin Function
1 +V
2 +V
3 +V
4 +V
5 −V
6 −V
7 −V
8 −V

EIS · PWR-DC12 power entry: barrel polarity and multi-pin pin functions + − center positive DC-004 DC-BAR21 2.1 × 5.5 mm about 2.5 A DC-BAR25 2.5 × 5.5 mm about 5 A Pin × barrel. A DC-BAR25 plug fits a DC-BAR21 DC entry loosely and is never inserted (ASM-004). Multi-pin variants and their pin functions DC-VH2 10 A pin 1 +V pin 2 −V DC-DIN4 15 A pin 1 +V pin 2 −V pin 3 −V pin 4 +V pin 5 shell DC-MF6 24 A pin 1 +V pin 2 +V pin 3 +V pin 4 −V pin 5 −V pin 6 −V DC-MF8 28 A pin 1 +V pin 2 +V pin 3 +V pin 4 +V pin 5 −V pin 6 −V pin 7 −V pin 8 −V A product with a multi-pin variant implements these pin functions (DC-005); its cables connect each pin to the same pin (DC-008). Modules take power from a PWR-DC12 outlet on DC-BAR21 or DC-VH2, never DC-BAR25 (DC-009).

Modules with a DC entry

A module may have both a power header and a DC entry. Such a module does not require both sources to be connected at the same time (PWR-003), and the installer connects only one (ASM-003). When the DC entry carries the load, the module's published bus currents (PWR-001) state what it draws from the bus, which may be nothing. It does not feed its DC rail back onto the bus (PWR-004), and the DC rail's −V is its 0 V (GND-001).

A module's barrel DC entry shall tolerate reverse polarity without damage (DC-006).

Cables

A straight DC barrel cable shall connect tip to tip and sleeve to sleeve at both ends (DC-007). A cable for a DC-VH2, DC-DIN4, DC-MF6, or DC-MF8 DC entry shall connect each pin to the same pin and function at both ends (DC-008).

Distribution to modules

A product with PWR-DC12 outlets to modules, a bus board, a DC entry panel, or a power supply (SUP-009), shall feed them only through DC-BAR21 jacks or DC-VH2 headers, never DC-BAR25 (DC-009). It shall protect each output separately and shall publish the current at which the protection acts (DC-012), so that one shorted cable takes down one module and not the rail, and its own DC entry shall tolerate reverse polarity without damage (DC-013). A cable from a DC distribution output to a module shall end in DC-BAR21 plugs or DC-VH2 housings and connect +V to +V and −V to −V, tip and pin 1 being +V (DC-010). A DC-BAR25 DC entry takes power from an adapter, not from a distribution product.

EIS · PWR-DC12 distribution: from the adapter to the modules adapter 12 V DC PWR-DC12 outlets bus board or entry panel DC-DIN4 or DC-BAR25 DC-VH2 module DC entry DC-VH2 module DC entry DC-BAR21 module DC entry DC-BAR25 never pin 1 = +V tip = +V A product with PWR-DC12 outlets feeds modules only through DC-BAR21 jacks or DC-VH2 headers, never DC-BAR25 (DC-009); its cables keep +V to +V (DC-010). DC-BAR25 takes power from an adapter. A DC-BAR25 plug fits a DC-BAR21 entry loosely and is never inserted (ASM-004).