1.10 VDD/VSS Rules And Guidelines
Introduction
STDL130
1-38
Samsung ASIC
Table 1-12.
Input Buffer Type
Ieq_p_in
(mA)
Output Pre-Driver
Type
Ieq_p_out
(mA)
1.8V Interface
Table 1-13.
Input Buffer Type
Ieq_p_in
(mA)
Output Pre-Driver
Type
Ieq_p_out
(mA)
2.5V Interface
Table 1-14.
Input Buffer Type
Ieq_p_in
(mA)
Output Pre-Driver
Type
Ieq_p_out
(mA)
3.3V Interface
ForreliabledeviceoperationandminimumIRvoltagedrop,atleast4pairsofVDD1P_LP/VSS1P_LP(VDD2P_LP,
3P_LP/VSS2P_LP, 3P_LP) power pads should be used.
1.10.4 VDD1O_LP/VSS1O_LP (VDD2O_LP, 3O_LP/VSS2O_LP, 3O_LP) ALLOCATION GUIDE
SSO (Simultaneous Switching Output) current induced in power and ground wire inductances can cause system
failure because of voltage spikes during switching. To calculate the number of output drive power pads, the SSO
noise as well as the current limit based on electromigration and taken into consideration. SSO is defined as the
number of outputs switching simultaneously in 1ns windows, such as bus type buffers.
NOTE:
In case of heavy loads, high frequency, and low package inductance, the number of power pads per SSO block
could be determined by the electromigration rule rather than the SSO noise limit. So, the number of power pads per
SSO block should be determined as the worst case power pad number determined by SSO noise and
electromigration rules.
1) Number of power pads for an SSO block
- Number of power pads for an SSO block under the limit of SSO noise
Calculating the number of power pad for each SSO group from the following expressions:
CMOS
0.27
0.28
Schmitt Trigger
0.28
0.29
Tristate
T8–16
0.41
0.41
Normal
Tolerant
CMOS Driver
B8–16
0.36
0.35
B1–4
0.11
0.11
B20–24
0.53
0.47
T1–4
0.15
0.16
T20–24
0.58
0.52
Tolerant
0.28
0.29
Normal
Slew-rate
CMOS
0.27
0.27
Schmitt Trigger
0.30
0.32
Tristate
T8–16
0.67
0.61
Normal
Tolerant
CMOS Driver
B8–16
0.60
0.55
B1–4
0.27
0.29
B20–24
0.84
0.72
T1–4
0.28
0.29
T20–24
0.77
0.71
Tolerant
0.39
0.42
Normal
Slew-rate
CMOS
0.32
0.31
Schmitt Trigger
0.38
0.34
Tristate
T8–16
0.59
0.58
Normal
Tolerant
CMOS Driver
B8–16
0.57
0.57
B1–4
0.32
0.30
B20–24
0.77
0.75
T1–4
0.34
0.31
T20–24
0.79
0.76
Tolerant
0.35
0.43
Normal
Slew-rate
NVDDO
each_SSO
number_of_SSO
NBvdd
NBvss
---------------------------------------------- L
pg
1
D
SSO_mode
1
D
SSO_mode
--------------------------
×
×
=
NVSSO
each_SSO
number_of_SSO
pg
--------------------------
×
×
=