PCI Express Card and PCI Express Mini Card

PCI Express (PCIe) is a serial, point-to-point high-speed expansion bus standard governed by the PCI Special Interest Group (PCI-SIG), introduced in 2003 as the successor to the parallel PCI and AGP buses. Full-size PCIe add-in cards use card-edge connectors at 1.0 mm contact pitch in x1, x4, x8, and x16 lane widths (36, 64, 98, and 164 pins respectively), carrying differential TX/RX pairs alongside +12 V and +3.3 V power rails; the same connector supports Gen 1 (2.5 GT/s), Gen 2 (5 GT/s), and Gen 3 (8 GT/s) signalling, defined in the PCIe Card Electromechanical Specification Rev 3.0 (July 2013). PCI Express Mini Card (Mini PCIe) is a compact form factor for laptop and embedded peripherals, using a 52-pin card-edge connector at 0.8 mm pitch and carrying one PCIe lane plus USB 2.0 signals; Full-Mini cards measure 30 × 51 mm and Half-Mini cards 30 × 26.8 mm, as specified in the PCI-SIG Mini Card Electromechanical Specification Rev 1.2.

PCI Express Card

• Verified with Congatec design

PCI Express - 1-lane slot

• Verified with PCI Express official specification

PCI Express Mini Card

• Verified with PCI Express Mini Card Electromechanical Specification, 1.0, with ECN

Notes

• The Mini PCIe connector has 52 pins arranged in two staggered rows at 0.8 mm pitch, with a 4-contact gap in each row acting as a mechanical key to prevent incorrect insertion.
• Full-Mini Card dimensions are 30 mm × 51 mm; Half-Mini Card dimensions are 30 mm × 26.8 mm; both use the same 52-pin connector footprint.
• 3.3Vaux is always present, including when the host system is in a low-power or sleep state, enabling the WAKE# function without main power.
• PERST# is asserted (active low) by the host to hold the card in reset until power is stable; it is deasserted to signal power-good and release the card.
• The REFCLK+/- differential pair provides the 100 MHz reference clock sourced from a clock buffer on the host side; CLKREQ# allows the card to gate this clock off to reduce power consumption.
• Mini PCIe COEX1/COEX2 are OEM-specific coexistence signals used, for example, to coordinate Bluetooth and Wi-Fi radio activity on combo modules; their function is not defined by the PCI-SIG specification.
• UIM (Universal Identity Module) pins provide an embedded SIM card interface; they are present only on WWAN (mobile broadband) Mini PCIe cards.
• For full-size PCIe x1 slots, the connector has 36 pins (18 per side A and B). Larger lane-width connectors have 64 (x4), 98 (x8), or 164 (x16) pins, all at 1.0 mm pitch.
• PCIe is backward and forward compatible within the same connector family: an x1 card operates in an x16 slot at x1 speed; an x16 card in an x8 slot negotiates to x8 speed.

Signals

• PERn0 / PERp0 — PCIe receive differential pair (card receives data from host), negative and positive conductors.
• PETn0 / PETp0 — PCIe transmit differential pair (card transmits data to host), negative and positive conductors.
• REFCLK- / REFCLK+ — 100 MHz differential reference clock input from the host clock buffer.
• CLKREQ# — Clock request output (active low); asserted by the card to request that the host enable the reference clock.
• PERST# — PCIe reset input (active low); deasserted by the host to release the card from reset once power rails are stable.
• WAKE# — Wake output (active low); asserted by the card to wake the host system from a low-power state.
• SMB CLK / SMB Data — System Management Bus clock and bidirectional data lines for out-of-band management.
• 3.3Vaux — 3.3 V auxiliary power supply, present even when main system power is off; supports WAKE# and card standby functions.
• 1.5 Volt — 1.5 V supply rail for card core logic.
• +12V — 12 V supply rail (full-size PCIe slot only).
• 3.3 Volt — 3.3 V main supply rail.
• W_DISABLE# — Wireless disable input (active low, Mini PCIe only); asserted by the host to disable the card’s radio transmitter, for example when required by aviation regulations.
• COEX1 / COEX2 — OEM-defined coexistence signals (Mini PCIe only); function varies by module and platform implementation.
• UIM PWR / UIM_DATA / UIM_CLK / UIM_RESET / UIM_VPP — Universal Identity Module (SIM card) interface signals for WWAN modules (Mini PCIe only).
• LED_WWAN# / LED_WLAN# / LED_WPAN# — Active-low LED drive outputs for WWAN, WLAN, and WPAN status indicators respectively (max 9 mA); Mini PCIe only.
• CP PE# — Card-present for PCI Express bus (ExpressCard form factor); signals to the host that the card uses the PCIe interface.
• CP USB# — Card-present for USB bus (ExpressCard form factor); signals to the host that the card uses the USB interface.
• PRSNT1# / PRSNT2# — Presence-detect pins (full-size PCIe slot); the add-in card shorts these together to signal its presence and enable hot-plug detection.
• JTAG1–JTAG5 — IEEE 1149.1 JTAG boundary-scan interface: reset, clock, data-in (TDI), data-out (TDO), and mode-select (TMS) (full-size PCIe slot).

PCI Express Cards - Compare Electrical Interfaces

References

• PCI Express Card Electromechanical Specification, Revision 3.0 (July 2013)
• PCI Express Mini Card Electromechanical Specification, Revision 1.2

Category:Buses Connectors