Rainbow Electronics LM93 - Manual (Page 61)

16.0 Registers
(Continued)
16.7.6 Register B4–BBh Fan Tach Limit Registers
Register
Address
Read/
Write
Register
Name
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Default
Value
B4h R/W
Fan Tach 1
Limit LSB
TLIMIT1[5:0] RES FCh
B5h R/W
Fan Tach 1
Limit MSB
TLIMIT1[13:6] FFh
B6h R/W
Fan Tach 2
Limit LSB
TLIMIT2[5:0] RES FCh
B7h R/W
Fan Tach 2
Limit MSB
TLIMIT2[13:6] FFh
B8h R/W
Fan Tach 3
Limit LSB
TLIMIT3[5:0] RES FCh
B9h R/W
Fan Tach 3
Limit MSB
TLIMIT1[13:6] FFh
BAh R/W
Fan Tach 4
Limit LSB
TLIMIT4[5:0] RES FCh
BBh R/W
Fan Tach 4
Limit MSB
TLIMIT4[13:6] FFh
If a tachometer reading exceeds its limit (as defined by these registers) the corresponding bit is set in the Host and BMC Error
Status registers. The fan tachometer readings can be associated with a particular PWM output, but the tach errors are not
automatically masked when a PWM is at 0% or set to level that causes the fan RPM to be below the limit purposely. In order to
prevent false errors, care needs to be taken to make sure that the Fan Tach Limits are properly set. Errors are never generated
for a fan if its limit is set to 3FFFh.
LM93
www.national.com 61