
- 28 -
Andigilog, Inc. 2006
www.andigilog.com
August 2006 - 70A05003
aSC7512
Register 6A-6Bh: Temperature Limit
Register
Address
Read/
Write
Register
Name
Bit 7
(MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
(LSB)
Default
Value
Lock
6Ah
R/W
Zone 1 Temp
Absolute Limit
7
6
5
4
3
2
1
0
64
X
6Bh
R/W
Zone 2 Temp
Absolute Limit
7
6
5
4
3
2
1
0
64
X
In the Auto Fan mode, if a zone exceeds the temperature set in the Absolute Temperature Limit register, all of the PWM
outputs will increase its duty cycle to 100%. This is a safety feature that attempts to cool the system if there is a potentially
catastrophic thermal event. If set to 80h (-128
°
C), the feature is disabled. Default = 100 C = 64h.
These registers become read-only when the Ready/Lock/Start/Override register Lock bit is set. Any further attempts to write
to these registers shall have no effect. After power up the default values are used whenever the Ready/Lock/Start/Override
register Start bit is cleared even though modifications to these registers are possible.
Temperature
Absolute Limit
(2’s Complement)
>127
°
C
+127
°
C
+125
°
C
0111
0111
0111
0110
0011
0001
0000
1100
1000
1000
1111
1111
1101
0100
0010
1001
0000
1110
0001
0000
+100
°
C (default)
+50
°
C
+25
°
C
0
°
C
-50
°
C
-127
°
C
-128
°
C (Disable)
Table 21 Absolute Temperature Limit Register -
8-Bit Two’s Complement
Register 6Dh: Thermal Zone Hysteresis
Register
Address
Read/
Write
Register
Name
Bit 7
(MSB)
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
(LSB)
Default
Value
Lock
6Dh
R/W
Zone 1 and
Zone 2
Hysteresis
H1-3
H1-2
H1-1
H1-0
H2-3
H2-2
H2-1
H2-0
44
X
If the temperature is above Fan Temp Limit, then drops below Fan Temp Limit, the following will occur:
The fan will remain on, at Fan PWM Minimum, until the temperature goes a certain amount below Fan Temp Limit.
The Hysteresis registers control this amount. See below table for details.
This register becomes read-only when the Ready/Lock/Start/Override register Lock bit is set. Any further attempts to write to
these registers shall have no effect. After power up the default value is used whenever the Ready/Lock/Start/Override
register Start bit is cleared even though modifications to this register are possible.
Temperature
Zone Hysteresis Hn-[3:0]
0
°
C
1
°
C
0000
0001
0100
1010
1111
4
°
C (default)
10
°
C
15
°
C
Table 22 Zone Hysteresis Register Format