SE98A Datasheet, PDF (11/43 Pages) NXP Semiconductors – DDR memory module temp sensor, 1.7 V to 3.6 V

NXP Semiconductors
SE98A
DDR memory module temp sensor, 1.7 V to 3.6 V
7.5 Power-up default condition
After power-on, the SE98A is initialized to the following default condition:
• Starts monitoring local sensor
• EVENT register is cleared—EVENT output is pulled HIGH by external pull-ups
• EVENT hysteresis is defaulted to 0 °C
• Command pointer is defaulted to ‘00h’
• Critical Temp, Alarm Temperature Upper and Lower Boundary Trip register are
defaulted to 0 °C
• Capability register is defaulted to ‘0037h’ for the B-grade and VHV capability
• Operational mode: comparator
• SMBus register is defaulted to ‘00h’
7.6 Device initialization
SE98A temperature sensors have programmable registers, which, upon power-up, default
to zero. The open-drain EVENT output is default to being disabled, comparator mode and
active LOW. The alarm trigger registers default to being unprotected. The configuration
registers, upper and lower alarm boundary registers and critical temperature window are
defaulted to zero and need to be programmed to the desired values. SMBus TIMEOUT
feature defaults to being enabled and can be programmed to disable. These registers are
required to be initialized before the device can properly function. Except for the SPD,
which does not have any programmable registers, and does not need to be initialized.
Table 4 shows the default values and the example value to be programmed to these
registers.
Table 4.
Register
01h
Registers to be initialized
Default value Example value
0000h
0209h
02h
0000h
03h
0000h
04h
0000h
22h
0000h
0550h
1F40h
05F0h
0000h
Description
Configuration register
• hysteresis = 1.5 °C
• EVENT output = Interrupt mode
• EVENT output is enabled
Upper Boundary Alarm Trip register = 85 °C
Lower Boundary Alarm Trip register = −20 °C
Critical Alarm Trip register = 95 °C
SMBus register = no change
SE98A_2
Product data sheet
Rev. 02 — 6 August 2009
© NXP B.V. 2009. All rights reserved.
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