
SPRS145G
–
JULY 2000
–
REVISED FEBRUARY 2002
20
POST OFFICE BOX 1443
HOUSTON, TEXAS 77251
–
1443
pin functions (continued)
Table 2. LF240xA and LC240xA Pin List and Package Options
(Continued)
PIN NAME
LF2407A
(144-PGE)
2406A
(100-PZ)
LC2404A
(100-PZ)
2403A,
LC2402A
(64-PAG)
and
2402A
(64-PG)
DESCRIPTION
EMULATION AND TEST (CONTINUED)
TRST
1
1
1
33
JTAG test reset with internal pulldown. TRST, when
driven high, gives the scan system control of the
operations of the device. If this signal is not
connected or driven low, the device operates in its
functional mode, and the test reset signals are
ignored.
(
↓
)
NOTE: Do not use pullup resistors on TRST; it has
an internal pulldown device. In a low-noise
environment, TRST can be left floating. In a
high-noise environment, an additional pulldown
resistor may be needed. The value of this resistor
should be based on drive strength of the debugger
pods applicable to the design. A 2.2-k
resistor
generally offers adequate protection. Since this is
application-specific, it is recommended that each
target board is validated for proper operation of the
debugger and the application.
ADDRESS, DATA, AND MEMORY CONTROL SIGNALS
DS
87
Data space strobe. IS, DS, and PS are always high
unless low-level asserted for access to the relevant
external memory space or I/O. They are placed in
the high-impedance state.
IS
82
I/O space strobe. IS, DS, and PS are always high
unless low-level asserted for access to the relevant
external memory space or I/O. They are placed in
the high-impedance state.
PS
84
Program space strobe. IS, DS, and PS are always
high unless low-level asserted for access to the
relevant external memory space or I/O. They are
placed in the high-impedance state.
R/W
92
Read/write qualifier signal. R/W indicates transfer
direction during communication to an external
device. It is normally in read mode (high), unless low
level is asserted for performing a write operation.
R/W is placed in the high-impedance state.
Bold, italicized pin names
indicate pin function after reset.
GPIO
–
General-purpose input/output pin. All GPIOs come up as input after reset.
§
It is highly recommended that VCCA be isolated from the digital supply voltage (and VSSA from digital ground) to maintain the specified accuracy
and improve the noise immunity of the ADC.
Only when all of the following conditions are met: EMU1/OFF is low, TRST is low, and EMU0 is high
#No power supply pin (VDD, VDDO, VSS, or VSSO) should be left unconnected. All power supply pins must be connected appropriately for proper
device operation.
LEGEND:
↑
–
Internal pullup
↓
–
Internal pulldown
(Typical active pullup/pulldown value is
±
16
μ
A.)