NXP Semiconductors MPC855TCVR66D4

Overview

MPC855TCVR66D4 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). It features 4 KB instruction/4 KB data cache, 66 MHz CPU operation, IEEE 802.3 10/100 Mbps Ethernet support via SCC, and UTOPIA-level ATM interface for broadband access equipment. It is used in carrier-grade DSLAMs and enterprise edge routers requiring deterministic real-time packet processing.

For engineers reviewing the MPC855TCVR66D4 datasheet, MPC855TCVR66D4 pinout, MPC855TCVR66D4 application, or MPC855TCVR66D4 equivalent, this page delivers verified technical context, package mapping to PBGA-357 (ZQ/VR), confirmed DC/AC timing at 66 MHz, thermal resistance values (RθJA = 34°C/W), and two validated alternative parts with documented functional and packaging differences.

Technical Context

The MPC855TCVR66D4 implements a dual-core architecture: a 32-bit Power Architecture CPU with MMU, instruction/data caches, and time base unit; and a separate CPM handling serial protocols (HDLC, UART, SPI, I²C) and ATM cell processing. Its memory controller supports eight banks with programmable wait states and glueless interfacing to DRAM, SRAM, Flash, and PCMCIA.

It operates at 3.3 V with 5-V-tolerant I/O (except EXTAL/EXTCLK), supports IEEE 1149.1 JTAG debug, and integrates a real-time clock, four 16-bit timers, and system-level features including watchdog, PIT, and clock synthesizer. The device uses a 357-pin PBGA (25×25 mm, 1.27 mm pitch, ZQ/VR package code) with thermal pad.

Key Specifications

Pinout & Package

Package: 357-ball PBGA (ZQ/VR), 25 mm × 25 mm, 1.27 mm pitch, exposed thermal pad (case temperature referenced to top center).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPC855TCVR66D4, MPC860T omits ATM acceleration but simplifies design for Ethernet-only nodes, while MPC860P retains full feature parity with doubled cache - enabling faster interrupt response and larger routing tables without external SRAM.

Availability

MPC855TCVR66D4 is available at Aetrix Electronics and suitable for DSLAM line card control, enterprise edge routing, industrial protocol gateway, and legacy telecom node controller applications requiring stable component supply across extended product lifecycles.

Supply support for MPC855TCVR66D4 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) is a fabless semiconductor company specializing in embedded processors, analog, and connectivity solutions for automotive, industrial, and networking markets.

The MPC855T belongs to the PowerQUICC™ family - designed specifically for communications infrastructure requiring integrated CPU+CPM architecture, deterministic real-time I/O, and protocol offload in space-constrained telecom equipment.

FAQ

What is the maximum operating frequency of the MPC855TCVR66D4 CPU core?

The MPC855TCVR66D4 CPU core operates at a maximum frequency of 66 MHz. This is confirmed in the hardware specifications document (Rev. 10, Section 9, Table 7), where bus timing is explicitly defined for 66 MHz operation. At this speed, the device maintains full functionality including CPM offload, Ethernet MAC, and UTOPIA ATM interface - unlike higher-speed MPC860 variants that require half-speed bus configuration. The MPC855TCVR66D4 must be configured with MF ≤ 2 to achieve stable 66 MHz operation.

Does the MPC855TCVR66D4 support IEEE 802.3 10/100 Mbps Ethernet?

Yes, the MPC855TCVR66D4 supports IEEE 802.3 10/100 Mbps Ethernet via its Serial Communications Controller (SCC), specifically SCC1–SCC4. As stated in Section 1 of the hardware specification, "10/100 Mbps Ethernet support, fully compliant with the IEEE 802.3u® Standard" is implemented. However, this capability is disabled when using the UTOPIA interface for ATM - a hardware resource conflict documented in the Features section. The MII pins (MII_TXD[0:3], MII_MDC, MII_MDIO) are electrically present and routable on the MPC855TCVR66D4 PBGA package.

What package type and pin count does the MPC855TCVR66D4 use?

The MPC855TCVR66D4 uses a 357-ball plastic ball grid array (PBGA) package with ZQ/VR package code (Case No. 5058, 1103D-02), measuring 25 mm × 25 mm with 1.27 mm ball pitch and an exposed thermal pad. This is specified in Table 3 ("Package Description") and confirmed in mechanical drawings referenced in Section 14. The ZQ/VR variant has 1.15 mm mold compound thickness and RθJB = 13°C/W - distinct from the thinner ZP variant (0.85 mm, RθJB = 14°C/W) used in other MPC860 family members.

What is the recommended power supply configuration for the MPC855TCVR66D4?

The MPC855TCVR66D4 requires two independent 3.3 V supplies: VDDH (I/O) and VDDL (core), both regulated to 3.135–3.465 V when operating above 40 MHz. Per Section 8 ("Layout Practices"), each VDD pin must be bypassed with ≥ four 0.1 µF capacitors placed within 0.5 inch of the package sides. The KAPWR pin (power-down mode) accepts 2.0–3.6 V. EXTAL and EXTCLK inputs are not 5 V tolerant - their high-level threshold is 0.7×VDDH, mandating level-shifting if driven from 5 V sources.

How does the MPC855TCVR66D4 handle thermal management in high-density PCB layouts?

The MPC855TCVR66D4 relies on board-level thermal conduction: its RθJB = 13°C/W (junction-to-board) dominates over RθJA = 34°C/W in typical 4-layer PCBs with ground/power planes. Section 7.3 specifies that junction temperature estimation must use TB (board temperature) and RθJB - not ambient - for accuracy. The exposed thermal pad must be soldered to a solid copper pour connected to internal ground planes. Airflow ≥200 ft/min reduces RθJMA to 18°C/W, but natural convection requires careful placement away from heat-generating components like power converters.