M34E02

14/23

Figure 11. Serial Presence Detect Block Diagram

Note: 1. E0, E1 and E2 are wired at each DIMM socket in a binary sequence for a maximum of 8 devices.

2. Common clock and common data are shared across all the devices.

3. Pull-up resistors are required on all SDA and SCL bus lines (typically 4.7 k

Ω) because these lines are open drain when used as

outputs.

R = 4.7k

Ω

AI01937

DIMM Position 7

SDA

SCL

E0

E1

E2

VCC

DIMM Position 6

SDA

SCL

E0

E1

E2

DIMM Position 5

SDA

SCL

E0

E1

E2

DIMM Position 4

SDA

SCL

E0

E1

E2

DIMM Position 3

SDA

SCL

E0

E1

E2

DIMM Position 2

SDA

SCL

E0

E1

E2

VCC

DIMM Position 1

SDA

SCL

E0

E1

E2

DIMM Position 0

SDA

SCL

E0

E1

E2

VSS

VSS

VSS

VCC

VSS

VSS VCC

VCC

VSS

VCC

VCC VSS

VSS

VCC

SCL line

SDA line

From the motherboard