NXP Semiconductors MPC855TCZQ50D4

Overview

MPC855TCZQ50D4 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 delivers 50 MHz system clock operation, 4 KB instruction/4 KB data cache, IEEE 802.3 10-Mbps Ethernet support on SCC1–4, and UTOPIA-level ATM cell processing up to 50–70 Mbps - deployed in telecom access gateways and industrial protocol converters.

For engineers reviewing the MPC855TCZQ50D4 datasheet, MPC855TCZQ50D4 pinout, MPC855TCZQ50D4 application, or MPC855TCZQ50D4 equivalent, key selection criteria include its 357-pin PBGA package, 3.3-V core I/O with 5-V TTL compatibility, dual-bus architecture supporting DRAM/SRAM/Flash, and CPM-based offloading of HDLC, UART, I²C, SPI, and FEC functions from the main CPU.

Technical Context

The MPC855TCZQ50D4 implements a superset of the MC68360 QUICC architecture with an enhanced CPM featuring I²C, additional serial DMA channels, and time-slot assigner (TSA) for T1/E1/PCM multiplexing. Its CPU core includes MMU with 32-entry TLB, 4-/8-KB configurable caches, and branch prediction without conditional execution.

It integrates a full memory controller supporting eight banks, PCMCIA socket controller (Rev. 2.1), real-time clock, IEEE 1149.1 JTAG debug interface, and four independent baud-rate generators. The device operates in multiple low-power modes - Doze, Sleep, Deep Sleep, and Power Down - with RTC and PIT retained in all states.

Key Specifications

Pinout & Package

MP855TCZQ50D4 uses a 357-ball plastic ball grid array (PBGA) package with ZQ designation (Case No. 5058, 25×25×1.2 mm, 1.27 mm pitch). Thermal resistance is RθJB = 13°C/W (four-layer board), RθJC = 8°C/W, and RθJA = 34°C/W (natural convection, single-layer board).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPC860T, MPC855TCZQ50D4 trades 100-Mbps Ethernet and higher clock headroom for lower power and cost; versus MPC855T, it offers superior thermal performance in compact enclosures due to ZQ package construction - making it the preferred choice for space-constrained telecom edge nodes requiring stable 50-MHz operation.

Availability

MPC855TCZQ50D4 is available at Aetrix Electronics and suitable for DSL access multiplexers, industrial protocol gateways, telecom signaling routers, and secure remote terminal units requiring stable component supply across extended product lifecycles.

Supply support for MPC855TCZQ50D4 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 since 2015) designed high-performance Power Architecture™ microcontrollers and communications processors for networking, automotive, and industrial markets.

The MPC855T belongs to the PowerQUICC™ family - engineered specifically for embedded communications control where deterministic real-time processing, protocol offload, and multi-interface integration are critical in space- and power-constrained platforms.

FAQ

What is the maximum operating frequency of the MPC855TCZQ50D4?

The MPC855TCZQ50D4 is rated for a maximum system clock frequency of 50 MHz. This applies to both the CPU core and the Communications Processor Module (CPM). While the MPC860 family includes variants rated up to 80 MHz, the MPC855TCZQ50D4's silicon revision (D.4) and characterization are validated strictly at 50 MHz - exceeding this frequency violates guaranteed timing margins and may cause CPM descriptor corruption or bus timeout errors. The MPC855TCZQ50D4 datasheet specifies DC and AC parameters only for 50-MHz operation.

Does the MPC855TCZQ50D4 support 100-Mbps Ethernet?

No, the MPC855TCZQ50D4 does not support 100-Mbps Ethernet. It supports 10-Mbps IEEE 802.3 Ethernet exclusively on SCC1–SCC4, and only when specially programmed per Freescale documentation. Unlike the MPC860T or MPC860P, the MPC855TCZQ50D4 lacks the MAC enhancements and PHY interface logic required for 100-Mbps operation. Its FEC unit is configured for 10-Mbps frame handling, and the bus timing specifications (e.g., B7–B9) are characterized only up to 50-MHz CLKOUT - insufficient for 100-Mbps MII timing compliance.

What package type and thermal characteristics apply to the MPC855TCZQ50D4?

The MPC855TCZQ50D4 uses a 357-ball PBGA package with ZQ designation (Case No. 5058, 25×25×1.2 mm, 1.27 mm pitch). Its thermal resistance values are RθJB = 13°C/W (junction-to-board, four-layer board), RθJC = 8°C/W (junction-to-case), and RθJA = 34°C/W (junction-to-ambient, natural convection, single-layer board). These values are measured per JEDEC JESD51-6 and JESD51-8 standards and reflect the thicker mold compound (1.15 mm) of the ZQ package versus the ZP variant - delivering measurably better board-level heat dissipation.

Can the MPC855TCZQ50D4 operate with a 3.0-V supply voltage?

The MPC855TCZQ50D4 may operate at 3.0 V only when running at ≤40 MHz, as specified in Table 6 of the hardware specification. At 50 MHz - its rated speed - the device requires VDDH/VDDL/KAPWR/VDDSYN to be maintained between 3.135 V and 3.465 V. Operating below 3.135 V at 50 MHz risks setup/hold violations on internal latches, cache tag mismatches, and CPM DMA descriptor pointer misalignment. The MPC855TCZQ50D4's power dissipation table (Table 5) also lists typical/max values only for 3.3 V and 3.5 V - confirming 3.0 V is outside validated operating conditions at full speed.

How many serial communication channels does the MPC855TCZQ50D4 integrate?

The MPC855TCZQ50D4 integrates four Serial Communications Controllers (SCCs) and two Serial Management Channels (SMCs). Each SCC supports HDLC/SDLC (up to 2 Mbps), UART, IrDA, BISYNC, and transparent bit-stream modes; SCC1–SCC4 can be configured for 10-Mbps Ethernet. Each SMC supports UART, transparent, and GCI modes, and can connect to TDM channels. Additionally, the device includes one SPI port and one I²C port - providing a total of eight independently configurable serial interfaces managed by the CPM.