NXP Semiconductors MPC855TCVR50D4

Overview

MPC855TCVR50D4 from Freescale Semiconductor is a 32-bit PowerPC-based communications controller integrating an MPC8xx core (106 MIPS @ 80 MHz), a RISC communications processor module (CPM), and a dedicated 10/100-Mbps Fast Ethernet controller (FEC) with bursting DMA and on-chip FIFOs. It supports ATM (UNI 4.0, up to 70 Mbps), QMC multichannel HDLC/transparent TDM (32 channels), and IEEE 802.3u Ethernet - all in a single 357-pin BGA package for SOHO routers and ADSL/cable modems.

For engineers reviewing the MPC855TCVR50D4 datasheet, MPC855TCVR50D4 pinout, MPC855TCVR50D4 application, or MPC855TCVR50D4 equivalent, key selection criteria include its dual-processor architecture (core + CPM), 8-KByte dual-port RAM, 3.3-V operation, UTOPIA/serial ATM interface options, and support for AAL0/AAL5 SAR - critical for embedded telecom control plane design.

Technical Context

The MPC855TCVR50D4 implements a true dual-processor architecture: the embedded MPC8xx core handles application-layer tasks using Dhrystone-optimized 4-KByte instruction/data caches and MMUs, while the CPM executes protocol offload (HDLC, ATM, QMC) via microcoded firmware and 10 SDMA channels. Its FEC operates independently of the CPM, enabling concurrent high-throughput Ethernet and serial communications without resource contention.

ATM processing occurs entirely within the CPM using ROM-resident microcode, supporting both UTOPIA Level 1 (8-bit, cell-level handshake, multi-PHY) and byte-aligned serial modes (T1/E1/ADSL). The QMC protocol maps up to 32 TDM time slots to a single SCC, with per-channel buffer descriptors and interrupt reporting - enabling scalable voice/data aggregation in access equipment.

Key Specifications

Pinout & Package

Package: 357-pin plastic ball grid array (PBGA), 27 × 27 mm, 1.27 mm pitch, thermally enhanced with exposed die paddle. Pinout validated per Freescale MPC855TTS/D Rev. 0.1 (Nov 2001) and MPC855T Hardware Specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPC855TCVR50D4, MPC860TBCZQ50D4 offers greater serial I/O density but lacks integrated FEC, while MPC8245LZQ50B provides higher CPU performance and PCI connectivity at the expense of communications-specific hardware acceleration - making MPC855TCVR50D4 uniquely balanced for integrated, low-cost telecom edge devices.

Availability

MPC855TCVR50D4 is available at Aetrix Electronics and suitable for SOHO router control planes, ADSL modem protocol stacks, cable modem termination systems, TDM voice gateways, and embedded telecom access equipment requiring stable component supply across extended product lifecycles.

Supply support for MPC855TCVR50D4 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 processing, networking, and automotive ICs. It pioneered the PowerQUICC family of communications processors.

The MPC855TCVR50D4 belongs to the MPC8xx PowerQUICC family, designed specifically for cost-sensitive, highly integrated communications controller applications in broadband access equipment - emphasizing glueless system design, dual-processor offload, and multi-protocol convergence (Ethernet/ATM/TDM).

FAQ

What is the maximum ATM throughput supported by the MPC855TCVR50D4?

The MPC855TCVR50D4 supports up to 70 Mbps of ATM cell processing bandwidth, measured at 50 MHz system clock. This is achieved through receive-priority arbitration between transmit and receive channels, allowing dynamic allocation - e.g., 51 Mbps receive + 19 Mbps transmit on a full-duplex T1/E1 link. Performance depends on AAL type (AAL0 vs. AAL5), interface mode (UTOPIA vs. serial), and microcode configuration. The MPC855TCVR50D4 datasheet specifies 50–70 Mbps range under typical conditions.

Does the MPC855TCVR50D4 support 100-Mbps full-duplex Ethernet operation?

Yes, the MPC855TCVR50D4 supports full-duplex 100-Mbps Ethernet operation when the system clock is 50 MHz or higher. It complies fully with IEEE 802.3u and supports three physical interfaces: 100-Mbps MII, 10-Mbps MII, and 10-Mbps 7-wire. Half-duplex 100-Mbps is supported at 33-MHz system clock and above. The FEC uses bursting DMA and large on-chip FIFOs to sustain line-rate throughput without stalling the core or CPM - a key feature confirmed in the MPC855TCVR50D4 Technical Summary.

How many TDM channels does the QMC multichannel protocol support on the MPC855TCVR50D4?

The QMC multichannel protocol on the MPC855TCVR50D4 supports up to 32 independent time-division-multiplexed channels over a single Serial Communications Controller (SCC). Each channel can operate in HDLC or transparent mode with independent transmit/receive buffer descriptors, event reporting, and arbitrary time-slot mapping (0–31 slots to 0–31 channels). This capability is explicitly documented for the MPC855TCVR50D4 in the QMC Supplement and MPC855T Technical Summary.

Is the MPC855TCVR50D4 pin-compatible with other MPC8xx family members?

No, the MPC855TCVR50D4 is not pin-compatible with other MPC8xx devices such as the MPC860 or MPC8260. It uses a unique 357-ball BGA footprint optimized for its integrated Fast Ethernet controller and UTOPIA interface. While functional similarities exist (e.g., shared CPM architecture and memory controller), pin assignments for FEC signals (MII_TXD/RXD), UTOPIA (TXD[3:0]/RXD[3:0]), and clock domains differ significantly. Migration requires PCB redesign - confirmed by Freescale's MPC855T Hardware Specification.

What power management modes are available on the MPC855TCVR50D4?

The MPC855TCVR50D4 supports five power management modes: Full-on (all units active), Doze (core units disabled except time base, decrementer, PLL, memory controller, RTC, and CPM in standby), Sleep (only RTC and periodic interrupt timer active), Deep Sleep (RTC and PIT active, PLL disabled), and Low-power STOP (minimal logic retained for wake-up). These modes are controlled via SIU registers and enable <100 µA standby current in STOP mode - detailed in Section 1.4 of the MPC855TCVR50D4 Technical Summary.