B- 12 M68040 USER’S MANUAL MOTOROLA
This device contains protective
circuitry against damage due to high
static voltages or electrical fields;
however, it is advised that normal
precautions be taken to avoid
application of any voltages higher
than maximum-rated voltages to this
high-impedance circuit. Reliablity of
operation is enhanced if unused
inputs are tied to an appropriate
logic voltage level (e.g., either GND
or V CC ).
B.6 SOFTWARE CONSIDERATIONS
The following MC68EC040 instructions are different from the MC68040: PTEST, PFLUSH,
CPUSH, CINV, MOVEC, and all floating-point instructions.
The PTEST and PFLUSH instructions should not be executed. Execution of the PTEST
instruction causes random bus cycles to occur. Execution of the PFLUSH instruction
produces indeterminate results. Neither instruction causes the MC68EC040 to generate
The CPUSH and CINV instructions require special consideration. A page is defined as a
4-Kbyte block of external memory. The CPUSH and CINV page instruction opcodes can
be used to push or invalidate 4-Kbyte blocks of memory. The MC68EC040 does not
support 8-Kbyte pages.
The MOVEC to URP and SRP instructions are not valid and will produce indeterminate
results. Each ACU has a status register and translation control register that replace the
MMU status register and translation control register of the MC68040. The MMU status
register opcode of the MOVEC instruction can modify the ACU status register. The
MC68EC040 ACU status register does not provide additional functionality to the ACU and
is only provided for compatibility with the ACU MC68EC030 status register. The ACU
status register may not be implemented in future M68EC0X0 products.
B.7 MC68EC040 ELECTRICAL CHARACTERISTICS
The following paragraphs provide information on the maximum rating and thermal
characteristics for the MC68EC040 only. Refer to Appendix C MC68040V and
MC68EC040V for more information on electrical characteristics for the MC68EC040V.
This section is subject to change. For the most recent specifications, contact a Motorola
sales office or complete the registration card at the end of this manual.
B.7.1 Maximum Ratings
Characteristic Symbol Value Unit
Supply Voltage VCC –0.3 to +7.0 V
Input Voltage Vin –0.8 to +7.0 V
Maximum Operating Junction Temperature TJ110 °C
Minimum Operating Ambient Temperature TA0°C
Storage Temperature Range Tstg –55 to 150 °C
B.7.2 Thermal Characteristics
Characteristic Symbol Value Rating
Thermal Resistance, Junction to Case—