Revision as of 15:48, 20 April 2022

Socket AM5 is a microprocessor socket designed by AMD for their fifth generation Ryzen desktop processors with CPU cores based on the Zen 4 microarchitecture, the successor to Socket AM4. It has counterparts in Socket SP5 for servers and the FP7 package for the mobile market.

Overview

Preliminary Data! Information presented in this article deal with future products, data, features, and specifications that have yet to be finalized, announced, or released. Information may be incomplete and can change by final release.

Socket AM5 is a zero insertion force, lever actuated, surface-mount land grid array socket for use with a 1718-contact, 0.81 mm × 0.94 mm interstitial pitch, organic land grid array CPU package.

The following AMD processor families use Socket AM5:

Socket AM5 supports two channels of DDR5 memory with two 36-bit subchannels (32 bit data + 4 bit ECC) and up to 2 DIMMs per channel, up to 28 lanes PCIe Gen 4/5, four of which are reserved to attach the chipset, four USB 3.2 Gen 2 or USB4 ports, one USB 2.0 port, and four digital display interfaces. SATA ports are provided by the chipset.

This compares to two DDR4 channels, 20 + 4 lanes PCIe Gen 3/4, four USB3 ports, and three DDIs on its predecessor Socket AM4.

Package Description

The AM5 CPU package is lidded, has a 40 mm × 40 mm organic substrate with flip chip die attachment, and 1718 land pads. The socket is not designed to be functional with unlidded packages.

The substrate has two keying notches preventing it from being inserted rotated into the socket, or incidentally into Socket F or Socket C32, two much older AMD sockets for LGA packages of the same size. Different keying options for future models are not evident, in any case AM5 packages are also electrically keyed by pin AM5R1 and Socket AM5 motherboards are not supposed to power up the socket if an incompatible processor is installed. A triangular symbol on both sides of the substrate marks the location of pin A1, with corresponding markings on the socket.

Owing to the increase of contacts from 1331 on Socket AM4 to 1718, AM5 packages have a higher contact density with the same pitch as Socket SP5, no components on the bottom side, and a redesigned lid a.k.a. integrated heat spreader which arcs over some of the top side decoupling capacitors providing more space for components.

AM5 processors are SoCs with an integrated controller hub so Socket AM5 pins out various low speed interfaces. The LPC interface present on the prior generation was deprecated in favor of SPI/ESPI. These busses are generally used to access firmware (PSP ROM and BIOS) i.e. flash memory, and a TPM. It is worth noting that the PSP can also provide TPM services. Added were I³C, and DMIC e.g. for Wake-On-Voice.

AM5 processors implement a USB BIOS update function enabled by a momentary switch on the motherboard during boot-up.

Socket Description

Socket AM5 has a 67 mm × 106 mm footprint and consists of the following components:

• Force Frame
• Socket Housing
• Cam Actuation Lever
• Stiffener Frame
• Insulators
• Backplate

Socket AM5 processors also require a heatsink.

The force frame, stiffener frame, and cam lever constitute the Socket Actuation Mechanism for toolless installation of the CPU. The heatsink, CPU, SAM, housing, and backplate are separately orderable parts, the latter three motherboard components for OEMs. Socket AM5 suppliers are TBD.

LGA sockets use cantilever springs in the socket housing to make electrical contact with flat pads on the bottom of the CPU package. The SAM creates the Z-axis compression load between the CPU package and the housing soldered to the motherboard, and to this end is attached to the backplate on the bottom side of the motherboard.

The force frame and stiffener frame are stamped out of 1.2 mm thick stainless steel sheets. The cam lever is made from 2.5 mm stainless steel wire. The force frame has a window allowing the top of the CPU package lid to protrude for contact with the heatsink. When closed and actuated with the cam lever it applies a load to the flanges on the sides of the lid. Markings include the name of the socket, supplier, a triangular pin A1 identifier, and a lot code on the force frame or stiffener frame. The force frame is hinged to the stiffener frame.

The stiffener frame has a window fitting the socket housing and incorporates a latch securing the lever in the actuated position. Four captive screws with #6-32 thread and Torx drive mount the stiffener frame to self-clinching PEM nuts protruding up from the backplate through holes in the PCB. Backplates with different nut heights are available to account for different PCB thicknesses. Two 0.18 mm thick insulating sheets in the shape of these parts separate them from the PCB.

Like Socket SP3 and SP5 the SAM apparently includes an external cap protecting the contact springs when no processor is installed.

The socket housing is an injection-molded plastic part, likely made of black liquid crystal polymer, and ships with a cover cap made of the same material which protects the contact springs and facilitates pick-and-place operation with a vacuum nozzle during board assembly. The housing outline is asymmetric, preventing the SAM and cover cap from being installed rotated. The walls have finger access cut-outs, keying features matching those on the CPU package, and a chamfered corner locating pin A1. Four undercut steps on the outside and an alignment hole suggest corresponding latches and an alignment peg on the cover cap. The springs extend into a J-lead at the bottom of the housing with solder balls attached for surface mounting. Standoffs limit the distance to the PCB.

Heatsink

The heatsink can be clipped onto a two-part retention frame made of plastic. The two-part design permits components closer to the socket and smaller boards. Each of the identical parts has an alignment peg preventing it from being installed rotated on the PCB which has correspondingly shaped through-holes. Two screws with #6-32 thread (like PC case screws; the closest metric substitute is the non-standard M3.5×0.8 thread) mount each part to a second set of taller PEM nuts, spaced 54 mm × 90 mm apart, which protrude up through the PCB from the backplate. Their height is some 5 mm leaving 4.34 mm headroom to the top of the package lid in the actuated socket. Heavier heatsinks can be attached directly to the backplate with four captive spring screws on the heatsink after removal of the retention frame. The positions of the retention frame latches and heatsink nuts are symmetric so the heatsink can be rotated 180 degrees.

The heatsink attachment facilities and the height of the processor in the actuated socket, 7.98 ± 0.60 mm from the top of the PCB to the top of the lid, are in line with Socket AM4 so heatsinks for that socket can be used.

Feature Summary

• Lidded land grid array package, 40 mm × 40 mm
  • 1718 contacts in a 44 × 40 grid, 0.81 mm × 0.94 mm interstitial pitch
  • Organic substrate, flip chip die attachment

• 2 × 64/72 bit DDR5 SDRAM interface
  • Data rate up to ?
  • Two DDR5 subchannels per DRAM channel, 32 bit data + 4 bit ECC
  • Up to 2 DIMMs/channel, up to 4 DIMMs total
  • SR/DR UDIMM or SO-DIMM types
  • Max. total memory capacity ? GiB using four ? GiB DIMMs

• PCIe Gen 4/5 (32 GT/s)
  • 16 lane graphics card interface, configurable 1x16, 2x8
  • 2 × 4 lanes general purpose (e.g. for M.2 NVME, PCIe slot, USB4 PCIe tunneling)
  • 4 lane chipset interface

• Up to four digital display interfaces
  • DP, eDP, SL DVI, HDMI protocols; LVDS and VGA via external DP to LVDS and DP to VGA translator
  • DP1-DP3 internally multiplexed with USBC0-USBC2 for DP Alt Mode

• Five USB ports from three or four USB controllers
  • 2 × USB 2.0, 3.2 Gen 1/2, USB4 (40 Gb/s), Type-C support, DP Alt Mode
  • 1 × USB 2.0, 3.2 Gen 1/2 (10 Gb/s), Type-C, DP Alt Mode
  • 1 × USB 2.0, 3.2 Gen 1/2 (10 Gb/s), Type-A
  • 1 × USB 2.0

• Low speed interfaces (some sharing pins):
  • HDA/SoundWire/DMIC
  • 2 × 1/2/4-bit SPI/eSPI
  • 4 × I³C/I²C
  • 2 × SMBus
  • GPIO
  • Sideband Interface (SB-TSI)
  • Serial VID Interface (SVI3)
  • JTAG

Note some processor models support only a subset of these features.

Chipsets

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Processors using Socket AM5

Photos

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Package Diagrams

AM5 package. All dimensions in millimeters.

Socket Diagrams

Socket AM5 housing (AMD). All dimensions in millimeters.

Socket AM5 backplate. All dimensions in millimeters.

Socket AM5 PCB layout. NPTH = Non-Plated Through Hole. All dimensions in millimeters.

Pin Map

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Pin Description

Bibliography

See also

• Socket AM4
• Socket SP5