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Pin Listing and Signal Definitions
Table 37. Signal Description (Page 8 of 8)
Name
THERMTRIP#
Description
Output
Assertion of THERMTRIP# (Thermal Trip) indicates the processor junction
temperature has reached a level beyond which permanent silicon damage may
occur. Measurement of the temperature is accomplished through an internal
thermal sensor which is configured to trip at approximately 135°C. Upon assertion
of THERMTRIP#, the processor will shut off its internal clocks (thus halting program
execution) in an attempt to reduce the processor junction temperature. To protect
the processor, its core voltage (Vcc) must be removed following the assertion of
THERMTRIP#. See Figure 19 and Table 22 for the appropriate power down
sequence and timing requirements.
For processors with CPUID of 0xF24:
Once activated, THERMTRIP# remains latched until RESET# is asserted. While
the assertion of the RESET# signal will de-assert THERMTRIP#, if the processor’s
junction temperature remains at or above the trip level, THERMTRIP# will again be
asserted.
For processors with CPUID of 0xF27 or higher:
Driving of the THERMTRIP# signal is enabled within 10 us of the assertion of
PWRGOOD and is disabled on de-assertion of PWRGOOD. Once activated,
THERMTRIP# remains latched until PWRGOOD is de-asserted. While the deassertion of the PWRGOOD signal will de-assert THERMTRIP#, if the processor’s
junction temperature remains at or above the trip level, THERMTRIP# will again be
asserted within 10 us of the assertion of PWRGOOD.
TMS
Input
TMS (Test Mode Select) is a JTAG specification support signal used by debug
tools.
TRDY#
Input
TRDY# (Target Ready) is asserted by the target to indicate that it is ready to receive
a write or implicit writeback data transfer. TRDY# must connect the appropriate pins
of all system bus agents.
TRST#
Input
TRST# (Test Reset) resets the Test Access Port (TAP) logic. TRST# must be driven
low during power on Reset. This can be done with a 680 ohm pull-down resistor.
VCCA
Input
VCCA provides isolated power for the internal processor core PLL’s. Refer to the
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Mobile Intel Pentium 4 Processor-M and Intel 845MP/845MZ Chipset Platform
Design Guide for complete implementation details.
VCCIOPLL
Input
VCCIOPLL provides isolated power for internal processor system bus PLL’s. Follow the
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guidelines for VCCA, and refer to the Mobile Intel Pentium 4 Processor-M and
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Intel 845MP/845MZ Chipset Platform Design Guide for complete implementation
details.
VCCSENSE
Output
VCCSENSE is an isolated low impedance connection to processor core power (VCC). It
can be used to sense or measure power near the silicon with little noise.
VCCVID
Input
VID[4:0]
VSSA
VSSSENSE
88
Type
Output
Input
Output
Independent 1.2-V supply must be routed to VCCVID pin for the Mobile Intel
Pentium 4 Processor-M’s Voltage Identification circuit.
VID[4:0] (Voltage ID) pins are used to support automatic selection of power supply
voltages (Vcc). Unlike some previous generations of processors, these are open
drain signals that are driven by the Mobile Intel Pentium 4 Processor-M and must
be pulled up to 3.3 V (max.) with 1-Kohm resistors. The voltage supply for these
pins must be valid before the VR can supply Vcc to the processor. Conversely, the
VR output must be disabled until the voltage supply for the VID pins becomes valid.
The VID pins are needed to support the processor voltage specification variations.
See Table 3 for definitions of these pins. The VR must supply the voltage that is
requested by the pins, or disable itself.
VSSA is the isolated ground for internal PLLs.
VSSSENSE is an isolated low impedance connection to processor core VSS. It can be
used to sense or measure ground near the silicon with little noise.
Mobile Intel Pentium 4 Processor-M Datasheet