PC7457

Notes:
1. Functional and tested operating conditions are given in Table 3 on page 12. Absolute maximum ratings are stress ratings only, and functional operation at the maximums is not guaranteed. Stresses beyond those listed may affect device reliability or cause permanent damage to the device.
2. Caution: VDD/AVDD must not exceed OVDD/GVDD by more than 1V during normal operation; this limit may be exceeded for a maximum of 20 ms during power-on reset and power-down sequences.
3. Caution: OVDD/GVDD must not exceed VDD/AVDD by more than 2V during normal operation; this limit may be exceeded for a maximum of 20 ms during power-on reset and power-down sequences.
4. BVSEL must be set to 0, such that the bus is in 1.8V mode.
5. BVSEL must be set to HRESET  or 1, such that the bus is in 2.5V mode.
6. L3VSEL must be set to ¬HRESET  (inverse of HRESET ), such that the bus is in 1.5V mode.

This document is primarily concerned with the PowerPC™ PC7457; however, unless otherwise noted, all information here also applies to the PC7447. The PC7457 and PC7447 are implementations of the PowerPC microprocessor family of reduced instruction set computer (RISC) microprocessors. This document describes pertinent electrical and physical characteristics of the PC7457.

The PC7457 is the fourth implementation of the fourth generation (G4) microprocessors from Motorola. The PC7457 implements the full PowerPC 32-bit architecture and is targeted at networking and computing systems applications. The PC7457 consists of a processor core, a 512 Kbyte L2, and an internal L3 tag and controller which support a glueless backside L3 cache through a dedicated high-bandwidth interface. The PC7447 is identical to the PC7457 except it does not support the L3 cache interface.

The PC7457 is a high-performance superscalar design supporting a double-precision floating-point unit and a SIMD multimedia unit. The memory storage subsystem of PC7457 supports the MPX bus interface to main memory and other system resources. The L3 interface supports 1, 2, or 4M bytes of external SRAM for L3 cache and/or private memory data. For systems implementing 4M bytes of SRAM, a maximum of 2M bytes may be used as cache; the remaining 2M bytes must be private memory. Note that the PC7457 is a footprint-compatible, drop-in replacement in a PC7455 application if the core power supply is 1.3V.