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Preliminary and subject to change without notice
PPC740 and PPC750 Hardware Specifications
7 of 43
Table 3 provides the package thermal characteristics for the PPC740 and PPC750.
management
The PPC740 and PPC750 incorporate a thermal management assist unit (TAU) com-
posed of a thermal sensor, digital-to-analog converter, comparator, control logic, and
dedicated special-purpose registers (SPRs). See the PowerPC 740TM PowerPC 750TM
RISC Microprocessor User’s Manual for more information on the use of this feature.
Specications for the thermal sensor portion of the TAU are found in Table 4.
Notes:
1.The temperature is the junction temperature of the die. The thermal assist unit's (TAU) raw output does
not indicate an absolute temperature, but it must be interpreted by software to derive the absolute
junction temperature. For information on how to use and calibrate the TAU, contact your local IBM
sales ofce. This specication reects the temperature span supported by the design.
2. The comparator settling time value must be converted into the number of CPU clocks that need to be
written into the THRM3 SPR.
3. This value is guaranteed by design and is not tested.
Table 5 provides DC electrical characteristics for the PPC740 and PPC750
.
Table 3. Package Thermal Characteristics
Characteristic
Symbol
Value
Unit
CBGA package thermal resistance, junction-to-case
thermal resistance (typical)
θJC
0.03
°C/W
CBGA package thermal resistance, junction-to-lead
thermal resistance (typical)
θJB
3.8
°C/W
Table 4. Thermal Sensor Specications
Num
Characteristic
Min
Max
Unit
Notes
1
Temperature range
0
128
°C1
2
Comparator settling time
20
—
ms
2
3
Resolution
4
—
°C3
Table 5. DC Electrical Specications
Characteristic
Symbol
Min
Max
Unit
Notes
Input high voltage (all inputs except SYSCLK)
VIH
2.0
3.465
V
1,2
Input low voltage (all inputs except SYSCLK)
VIL
GND
0.8
V
SYSCLK input high voltage
CVIH
2.4
OVdd
V
1
SYSCLK input low voltage
CVIL
GND
0.4
V