se98pw NXP Semiconductors, se98pw Datasheet - Page 7

• Manufacturer Part Number: se98pw
• Description: Se98 So-dimm Smbus/i2c-bus Temperature Sensor
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SE98_2
Product data sheet
7.5 Power-up default condition
7.6 Device initialization
7.7 SMBus Time-out
After power-on, the SE98 is initialized to the following default condition:
SE98 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 3
registers.
Table 3.
The SE98 supports the SMBus time-out feature. If the host holds SCL LOW between
25 ms and 35 ms, the SE98 would reset its internal state machine to the bus idle state to
prevent the system bus hang-up. This feature is turned on by default. The SMBus time-out
is disabled by writing a logic 1 to bit 7 of register 22h.
Remark: When SMBus time-out is enabled, the I
the SMBus time-out timer, and goes down to only 10 kHz.
Register
01h
02h
03h
04h
22h
•
•
•
•
•
•
•
•
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 ‘0015h’
Operational mode: comparator
SMBus register is defaulted to ‘00h’
shows the default values and the example value to be programmed to these
Registers to be initialized
Default value
0000h
0000h
0000h
0000h
0000h
Rev. 02 — 7 January 2008
Example value
0209h
0550h
1F40h
05F0h
0000h
SO-DIMM SMBus/I
Description
Configuration register
Upper Boundary Alarm Trip register = 85 C
Lower Boundary Alarm Trip register = 20 C
Critical Alarm Trip register = 95 C
SMBus register = no change
•
•
•
2
C-bus minimum bus speed is limited by
hysteresis = 1.5 C
EVENT output = Interrupt mode
EVENT output is enabled
2
C-bus temperature sensor
© NXP B.V. 2008. All rights reserved.
SE98
7 of 32