Datasheet
PowerPC 970FX RISC Microprocessor
Table 5-8. Input/Output Signal Descriptions (Page 4 of 4)
Pin Name
Width
1
In/Out
In
System/Debug Function
System: time base enable.
Notes
—
TBEN
TCK
JTAG: test clock that is separate from the system clock. Controls all
test access port functions.
1
1
In
In
2
2
JTAG: serial input used to feed test data and test access port instruc-
tions.
TDI
JTAG: Serial output used to extract data from the chip under test con-
trol.
TDO
1
1
1
Out
In
—
—
—
THERM_INT
TMS
System: external thermal interrupt when low.
JTAG: Select used to control the operation of the JTAG state
machine.
In
TRIGGERIN
1
1
1
In
Out
In
External trigger to start trace collection.
—
—
11
TRIGGEROUT
TRST
Signal that indicates that internal trace collection has begun.
JTAG: asynchronous reset for the JTAG state machine.
Notes:
1. These are test signals for factory use only and must be pulled up to OV for normal processor operation.
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2
2. For I C or JTAG operation, the TCK and TDI signals must be pulled down to ground with a 10 kΩ resistor. See Section 3.10.3 on
page 43.
3. Bus ratios 8:1 and 16:1 are not supported for PI Input functionality.
4. These are test signals for factory use only and must be pulled down to GND for normal processor operation.
5. This signal should not be connected.
6. These pins can be used to measure on-chip voltage drop and noise. They should be connected to a backside probe point
immediately behind the module. They should not be connected to GND and V planes.
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7. BiDi = bidirectional. OD = open drain.
8. Using the 4:1 or 12:1 ratio with multiplier of 12 limits the use of power tuning to (frequency)/2.
9. The PLL_MULT and PLL_RANGE(1:0) bits can be overwritten by JTAG commands and the BUS_CFG bits can be changed by
SCOM commands during the POR sequence. See the PowerPC 970FX Power On Reset Application Note for more details
10. Must be pulled down with a 10 kΩ resistor to GND.
11. The TRST signal must be pulled up to OV with a 10 kΩ resistor.
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System Design Information
Page 74 of 78
Version 2.5
March 26, 2007
IBM [ IBM ]
