ASM2I99456G-32-ER PULSECORE [PulseCore Semiconductor], ASM2I99456G-32-ER Datasheet - Page 9

• Manufacturer Part Number: ASM2I99456G-32-ER
• Description: 3.3V/2.5V LVCMOS Clock Fanout Buffer
• Manufacturer: PULSECORE [PulseCore Semiconductor]

November 2006
rev 0.3
Power Consumption of the ASM2I99456 and
Thermal Management
The ASM2I99456 AC specification is guaranteed for the
entire operating frequency range up to 250MHz. The
ASM2I99456 power consumption and the associated
long-term
frequency limit, depending on operating conditions such
as clock frequency, supply voltage, output loading,
ambient temperature, vertical convection and thermal
conductivity of package and board. This section
describes the impact of these parameters on the junction
temperature and gives a guideline to estimate the
ASM2I99456 die junction temperature and the associated
device reliability.
Table 11. Die junction temperature and MTBF
Increased power consumption will increase the die
junction temperature and impact the device reliability
(MTBF). According to the system-defined tolerable
MTBF, the die junction temperature of the ASM2I99456
needs to be controlled and the thermal impedance of the
board/package
dissipated in the
equation 1.
Junction temperature (°C)
reliability
100
110
120
130
should
ASM2I99456
may
be
decrease
optimized.
Notice: The information in this document is subject to change without notice.
3.3V/2.5V LVCMOS Clock Fanout Buffer
MTBF (Years)
is represented in
the
20.4
9.1
4.2
2.0
The
maximum
power
Where I
ASM2I99456, C
per output,
output load, N is the number of active outputs (N is
always 12 in case of the ASM2I99456). The ASM2I99456
supports driving transmission lines to maintain high signal
integrity and tight timing parameters. Any transmission
line will hide the lumped capacitive load at the end of the
board trace, therefore,
transmission line systems and can be eliminated from
equation 1. Using parallel termination output termination
results in equation 2 for power dissipation.
In equation 2, P stands for the number of outputs with a
parallel or thevenin termination, V
a function of the output termination technique and DC
the clock signal duty cycle. If transmission lines are used
Σ
general,
techniques eliminates the impact of the lumped capacitive
loads at the end lines and greatly reduces the power
dissipation of the device. Equation 3 describes the die
junction temperature T
consumption.
Where R
(junction to ambient) and T
According to Table 11, the junction temperature can be
used to estimate the long-term device reliability. Further,
combining equation 1 and equation 2 results in a
maximum operating frequency for the ASM2I99456 in a
series terminated transmission line system, equation 4.
CL is zero in equation 2 and can be eliminated. In
CCQ
thja
the
(Μ)Σ
is the thermal impedance of the package
is the static current consumption of the
use
PD
C
is the power dissipation capacitance
L
represents the external capacitive
of
J
controlled
as a function of the power
Σ
A
C
is the ambient temperature.
L
is zero for controlled
ASM2I99456
OL
, I
OL
transmission
, V
OH
9 of 14
and I
OH
Q
line
are
is