Datasheet, Volume 1
73
Signal Descriptions
TDI
I
TDI (Test Data In) transfers serial test data into the processor.
TDI provides the serial input needed for JTAG specification
support.
TDO
O
TDO (Test Data Out) transfers serial test data out of the
processor. TDO provides the serial output needed for JTAG
specification support.
TESTLOW
I
TESTLOW must be connected to ground through a resistor for
proper processor operation.
THERMTRIP#
O
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. 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
further protect the processor, its core voltage (V
CC
), V
TTA
V
TTD
,
and V
DDQ
must be removed following the assertion of
THERMTRIP#. Once activated, THERMTRIP# remains latched
until RESET# is asserted. While the assertion of the RESET#
signal may de-assert THERMTRIP#, if the processor junction
temperature remains at or above the trip level, THERMTRIP#
will again be asserted after RESET# is de-asserted.
TMS
I
TMS (Test Mode Select) is a JTAG specification support signal
used by debug tools.
TRST#
I
TRST# (Test Reset) resets the Test Access Port (TAP) logic.
TRST# must be driven low during power on Reset.
VCC
I
Power for processor core.
VCC_SENSE
VSS_SENSE
O
O
VCC_SENSE and VSS_SENSE provide an isolated, low
impedance connection to the processor core power and
ground. They can be used to sense or measure voltage near
the silicon.
VCCPLL
I
Power for on-die PLL filter.
VCCPWRGOOD
I
VCCPWRGOOD (Power Good) is a processor input. The
processor requires this signal to be a clean indication that
BCLK, V
CC
, V
CCPLL
, V
TTA
and V
TTD
supplies are stable and
within their specifications. 'Clean' implies that the signal will
remain low (capable of sinking leakage current), without
glitches, from the time that the power supplies are turned on
until they come within specification. The signal must then
transition monotonically to a high state. VCCPWRGOOD can be
driven inactive at any time, but BCLK and power must again
be stable before a subsequent rising edge of VCCPWRGOOD.
In addition, at the time VCCPWRGOOD is asserted RESET#
must be active. The PWRGOOD signal must be supplied to the
processor. It should be driven high throughout boundary scan
operation.
VDDPWRGOOD
I
VDDPWRGOOD is an input that indicates the V
DDQ
power
supply is good. The processor requires this signal to be a clean
indication that the V
DDQ
power supply is stable and within
specifications. "Clean" implies that the signal will remain low
(capable of sinking leakage current), without glitches, from
the time that the V
DDQ
supply is turned on until it comes
within specification. The signals must then transition
monotonically to a high state.
The PWRGOOD signal must be supplied to the processor.
Table 5-1.
Signal Definitions (Sheet 3 of 4)
Name
Type
Description
Notes
Содержание BX80613I7980
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