se97b NXP Semiconductors, se97b Datasheet - Page 36

• Manufacturer Part Number: se97b
• Description: Ddr Memory Module Temp Sensor With Integrated Spd
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SE97B_1
Product data sheet
9.1 SE97B in memory module application
9.2 Layout consideration
9.3 Thermal considerations
Figure 21
is 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 SE97B triggers the EVENT output and the memory controller throttles
the memory bus to slow the DRAM. The memory controller can also read the SE97B and
watch the DRAM thermal behavior, taking preventive measures when necessary.
The SE97B does not require any additional components other than the host controller to
read its temperature. It is recommended that a 0.1 μF 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 SE97B, 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:
ΔT
[
Fig 21. System application
(
ΔT = T
T
T
R
V
I
DD(AV)
V
j
amb
DD
th(j-a)
DD
= junction temperature
=
SS
= supply voltage
R
= ambient temperature
×
th j-a
j
= package thermal resistance
pins is located as close as possible to the power and ground pins for noise
= average supply current
I
− T
DD AV
shows the SE97B being placed in the memory module application. The SE97B
(
is the formula to calculate the effect of self-heating:
(
amb
)
DIMM
×
)
DRAM
)
+
(
V
Rev. 01 — 27 January 2010
OL SDA
MEMORY CONTROLLER
(
)
DRAM
×
DDR memory module temp sensor with integrated SPD
I
OL
(
SMBus
sin
k
) SDA
(
SE97B
)
)
+
(
V
OL EVENT
(
EVENT
DRAM
)
×
I
OL
(
sin
k
DRAM
)EVENT
CPU
002aae315
© NXP B.V. 2010. All rights reserved.
SE97B
)
]
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DD
(1)