NXP Semiconductors MPC855TZQ50D4

Overview

MPC855TZQ50D4 from Freescale Semiconductor is a PowerQUICC™ integrated communications controller combining a 32-bit Power Architecture™ CPU core and a RISC-based Communications Processor Module (CPM) in a single PBGA357 package. It features 4 KB instruction and 4 KB data caches, supports 10/100 Mbps Ethernet via SCC, includes an I²C port and four serial communications controllers (SCCs), and targets embedded networking applications such as DSL gateways and industrial protocol converters.

For engineers reviewing the MPC855TZQ50D4 datasheet, MPC855TZQ50D4 pinout, MPC855TZQ50D4 application, or MPC855TZQ50D4 equivalent, key selection considerations include its 50 MHz system clock rating, 3.3 V core/I/O operation with 5 V-tolerant inputs (except EXTAL/EXTCLK), IEEE 802.3u-compliant Ethernet support, UTOPIA-level ATM interface capability, and compatibility with MPC860-family software and toolchains.

Technical Context

The MPC855TZQ50D4 implements a dual-core architecture: a 32-bit Power Architecture™ CPU with MMU, instruction/data caches, and branch prediction; and a separate RISC CPM handling serial protocols (HDLC, UART, IrDA, BISYNC), time-slot assignment, and peripheral control. Its memory controller supports DRAM, SRAM, Flash, and PCMCIA with dynamic bus sizing (8/16/32-bit) and up to eight banks.

It integrates IEEE 1149.1 JTAG debug, real-time clock, periodic interrupt timer, watchdog, and clock synthesizer in the System Integration Unit (SIU). The CPM includes 8 KB dual-port RAM, 16 SDMA channels, four baud-rate generators, and supports AAL0/AAL5 ATM cell processing at up to 70 Mbps with UTOPIA or serial physical interfaces.

Key Specifications

Pinout & Package

MP855TZQ50D4 is housed in a 357-ball plastic ball grid array (PBGA) package with ZQ designation (Case No. 5058, 25×25×1.2 mm, 1.27 mm pitch), requiring controlled-impedance PCB layout, thermal vias to ground plane, and strict decoupling (≥4 × 0.1 µF capacitors near package edges).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar integrated communications controller applications.

Compared with MPC860TZQ50D4, MPC855TZQ50D4 reduces silicon area and power by omitting redundant Ethernet MAC logic, making it optimal for single-link DSL or serial gateway designs; versus MPC852TVZQ50D4, it delivers full CPM-based protocol acceleration essential for real-time telecom edge nodes.

Availability

MPC855TZQ50D4 is available at Aetrix Electronics and suitable for DSL access multiplexers, industrial protocol gateways, secure remote terminal units, and legacy network bridges requiring stable component supply across extended product lifecycles.

Supply support for MPC855TZQ50D4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Freescale Semiconductor (now part of NXP Semiconductors) designed high-performance Power Architecture™ microcontrollers for networking, automotive, and industrial control markets.

The MPC855T belongs to the PowerQUICC™ family, engineered specifically for integrated communications processing in space-constrained, real-time embedded systems requiring both CPU general-purpose compute and hardware-accelerated serial protocol handling.

FAQ

What is the maximum operating frequency of the MPC855TZQ50D4?

The MPC855TZQ50D4 is rated for a 50 MHz system clock frequency. This is specified in the DC characteristics table and confirmed by timing parameters in the bus signal timing section (Table 7), where 50 MHz timing values are explicitly listed. Operating above this frequency violates the device's validated AC specifications and may cause data corruption or functional failure. The MPC855TZQ50D4 does not support the 66 MHz or 80 MHz modes documented for higher-tier MPC860 variants.

Does the MPC855TZQ50D4 support IEEE 802.3u 100BASE-TX Ethernet?

Yes, the MPC855TZQ50D4 supports IEEE 802.3u 100BASE-TX Ethernet through its SCC peripherals. As stated in the Overview and Features sections, it provides "10/100 Mbps Ethernet support, fully compliant with the IEEE 802.3u® Standard", and Table 1 confirms Ethernet capability for the MPC855T variant. This functionality requires external PHY connectivity via the MII interface (MII_MDC, MII_MDIO, MII_TXD[0:3], etc.) and proper configuration of SCC1–SCC4 in Ethernet mode.

What package type and pin count does the MPC855TZQ50D4 use?

The MPC855TZQ50D4 uses a 357-ball plastic ball grid array (PBGA) package with ZQ designation (Case No. 5058, 25 mm × 25 mm, 1.27 mm pitch), as defined in Table 3 of the hardware specification. This matches the MPC860 family's ZQ/VR package code and differs from the ZP variant by mold compound thickness (1.15 mm vs. 0.85 mm), impacting thermal resistance (RθJB = 13 °C/W for ZQ).

Can the MPC855TZQ50D4 operate with 5 V on its I/O pins?

The MPC855TZQ50D4 supports 5 V-tolerant inputs on most pins (VIH up to 5.5 V), but with a critical restriction: input voltage must not exceed VDDH + 2.5 V at any time, including power-up. EXTAL and EXTCLK pins are exceptions - they are not 5 V tolerant and require VIHC = 0.7×VDDH to VDDH+0.3 V. All I/O drivers output CMOS levels referenced to VDDH (3.3 V), so external 5 V logic requires level-shifting.

What debugging interfaces are available on the MPC855TZQ50D4?

The MPC855TZQ50D4 includes IEEE 1149.1 (JTAG) test access port for boundary-scan and on-chip emulation, plus an advanced debug interface with eight hardware comparators (four for instruction address, two for data address, two for data value) supporting break conditions (=, ≠, <, >). These features enable non-intrusive code tracing, real-time watchpoints, and hardware-assisted breakpoint triggering - essential for validating complex CPM firmware and timing-critical protocol stacks.