MPC7457 datasheet(13/71 Pages) FREESCALE

13 / 71 page

Electrical and Thermal Characteristics

MPC7457 RISC Microprocessor Hardware Specifications, Rev. 8

Freescale Semiconductor

Figure 2. Overshoot/Undershoot Voltage

The MPC7457 provides several I/O voltages to support both compatibility with existing systems and

migration to future systems. The MPC7457 core voltage must always be provided at nominal 1.3 V (see

Table 4 for actual recommended core voltage). Voltage to the L3 I/Os and processor interface I/Os are

provided through separate sets of supply pins and may be provided at the voltages shown in Table 3. The

input voltage threshold for each bus is selected by sampling the state of the voltage select pins at the

negation of the signal HRESET. The output voltage will swing from GND to the maximum voltage applied

to the OVDD or GVDD power pins.

Table 3. Input Threshold Voltage Setting

BVSEL Signal

Processor Bus Input Threshold

is Relative to:

L3VSEL Signal 1

L3 Bus Input Threshold is

Relative to:

Notes

1.8 V

2, 3

¬HRESET

Not Available

¬HRESET

1.5 V

2, 4

HRESET

2.5 V

HRESET

2.5 V

Notes:

1. Not implemented on MPC7447.

Caution: The input threshold selection must agree with the OV

DD/GVDD voltages supplied. See notes in Table 2.

3. If used, pull-down resistors should be less than 250

Ω.

4. Applicable to L3 bus interface only. ¬HRESET is the inverse of HRESET.

VIH

GND

GND – 0.3 V

GND – 0.7 V

Not to exceed 10%

OVDD/GVDD + 20%

VIL

OVDD/GVDD

OVDD/GVDD + 5%

of tSYSCLK

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