Ground Pins
© 2011 Advanced Micro Devices, Inc.
46136 AMD RX881 Databook 1.40
Proprietary
3-9
3.9
Ground Pins
3.10
Strapping Options
The RX881 provides strapping options to define specific operating parameters. The strap values are latched into internal
registers after the assertion of the POWERGOOD signal to the RX881.
Table 3-11, “Strap Definitions for the RX881,”
shows the definitions of all the strap functions. These straps are set by one of the following four methods:
•
Attaching pull-up resistors to specific strap pins listed in
Table 3-11
to set their values to “1”.
•
Attaching pull-down resistors to specific strap pins listed in
Table 3-11
to set their values to “0”.
•
Downloading the strap values from an I
2
C serial EEPROM (for debug purpose only; contact your AMD CSS
representative for details).
•
Setting through an external debug port, if implemented (contact your AMD CSS representative for details).
All of the straps listed in
Table 3-11
are defined active low. To select “1”, the strap pins must be pulled up to VDD33
through resistors. To select “0”, the strap pins must be pulled down to VSS through resistors. During reset, the strap pins
are undriven, allowing the external pull-up or pull-down to pull a pin to “0” or “1.” The values on the strap pins are then
latched into the device and used as operational parameters. However, for debug purposes, those latched values may be
overridden through an external debug strap port or by a bit-stream downloaded from a serial EEPROM.
Table 3-10 Ground Pins
Pin Name
Pin Count
Ball Reference
Comments
AVSSDI
1
G15
Connect the pin to common ground.
AVSSQ
1
H14
Connect the pin to common ground.
IOPLLVSS
1
AD23
Connect the pin to common ground.
PLLVSS
1
B12
Connect the pin to common ground.
VSS
37
AA14, AB11, AB15, AB17,
AB19, AB21, AC12, AE14,
AE20, D11, E14, E15, F18,
F19, G17, G8, J12, J15, K11,
K14, L12, L15, M11, M14, N13,
P12, P15, R11, R14, T12, U11,
U14, U15, V12, W11, W15,
Y18
Common Ground
VSSAHT
27
A25, AD25, D23, E22, G22,
G24, G25, H19, H20, J22,
L17, L22, L24, L25, M20, N22,
P20, R19, R22, R24, R25,
U22, V19, W22, W24, W25,
Y21
Ground pin for HyperTransport interface PLL
VSSAPCIE
40
A2, AA4, AB1, AB2, AB5, AB7,
AC3, AC4, AE1, AE4, B1, D3,
D5, E4, G1, G2, G4, H7, J4,
L1, L2, L4, L7, M6, N4, P6, R1,
R2, R4, R7, U4, V6, V7, V8,
W1, W2, W4, W7, W8, Y6
Ground for PCI Express Interface
VSSLT
7
C14, C16, C18, C20, C22,
D15, E20
Connect these pins to common ground
VSSLTP18
1
B13
Connect the pin to common ground
Total Ground Pin Count
116