se97pw/1 NXP Semiconductors, se97pw/1 Datasheet - Page 29

• Manufacturer Part Number: se97pw/1
• Description: Se97 Memory Module Temp Sensor With Integrated Spd
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SE97_2
Product data sheet
9.1 SE97 in memory module application
9.2 Layout consideration
9.3 Thermal considerations
Figure 22
centered in the memory module to monitor the temperature of the DRAM and also to
provide a 2-kbit EEPROM as the Serial Presence Detect (SPD). In the event of
overheating, the SE97 triggers the EVENT output and the memory controller throttles the
memory bus to slow the DRAM. The memory controller can also read the SE97 and watch
the DRAM thermal behavior, taking preventive measures when necessary.
The SE97 does not require any additional components other than the host controller to
read its temperature. It is recommended that a 0.1 F bypass capacitor between the V
and V
protection.
In general, self-heating is the result of power consumption and not a concern, especially
with the SE97, which consumes very low power. In the event the SDA and EVENT pins
are heavily loaded with small pull-up resistor values, self-heating affects temperature
accuracy by approximately 0.5 C.
Equation 1
where:
Fig 22. System application
T
V
T
T
R
V
I
DD(AV)
T = T
j
amb
DD
th(j-a)
DD
=
= junction temperature
SS
= supply voltage
R
= ambient temperature
th j-a
I
pins is located as close as possible to the power and ground pins for noise
j
= package thermal resistance
= average supply current
DD AV
shows the SE97 being placed in the memory module application. The SE97 is
is the formula to calculate the effect of self-heating:
T
amb
DIMM
DRAM
+
V
Rev. 02 — 12 October 2007
OL SDA
MEMORY CONTROLLER
DRAM
I
OL
SMBus
sin
Memory module temp sensor with integrated SPD
k
SDA
SE97
+
V
OL EVENT
EVENT
DRAM
I
OL
sin EVENT
DRAM
k
CPU
002aac800
© NXP B.V. 2007. All rights reserved.
SE97
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DD
(1)