U2
LPDDR4 SDRAM
IC
System memory
About this component
The Pi 4's only system memory, connected directly to the BCM2711. The size is fixed at manufacture and is read by the firmware from the board revision code. Raspberry Pi had to move a switch-mode supply on the board for the 8 GB model because its memory draws higher peak current. Memory faults show up as boot failures with a specific LED flash pattern; BGA rework is the only fix. Part variants: Fitted in 1, 2, 4 or 8 GB sizes. Raspberry Pi says the 8 GB board uses a Micron 8 GB LPDDR4 package; part numbers for the other sizes were not found in a reliable source.
What it does on this board
1–8GB LPDDR4 next to the SoC.
Pinout & readings
No pinout or reference readings yet — these show what each pin does and what a healthy part should measure.