TP3155N

Telecom Overview

The TP3155N is a monolithic CMOS Time Slot Assignment Circuit (TSAC) designed to generate transmit and receive frame synchronization pulses for up to eight COMBO CODEC/Filter units. It supports frames with up to 32 time slots, allowing independent assignment of each pulse via an 8-bit serial control word compatible with TP3020/TP3021 interfaces. The device operates on a single 5V supply with a typical current consumption of 1.5 mA at 2.048 MHz BCLK. It features LS TTL and CMOS compatible inputs, two operating modes for flexible channel mapping, and provides dedicated FSX/FSR outputs alongside a TSX status signal.

Telecom Feature Summary

• Generates independent transmit and receive frame sync pulses for up to 8 channels
• Supports time slot assignments within frames containing up to 32 slots
• Features a serial control interface compatible with standard TP3020/TP3021 CODECs
• Includes dual operating modes for separate or unified transmit/receive synchronization

Telecom Applications

• Synchronous line card applications in telecommunications systems
• Time slot assignment for COMBO CODEC/Filter arrays
• Frame synchronization generation for PCM bus buffering

Telecom Procurement Notes

Verify the component manufacturer origin, as National Semiconductor assets were acquired by Texas Instruments. Confirm the package type matches the required N20A Dual-In-Line specification. Ensure the design accounts for the specific timing constraints defined in the datasheet regarding setup and hold times relative to the bit clock.

Telecom Selection Notes

Select this component when interfacing with legacy COMBO CODEC families requiring precise frame synchronization. Evaluate Mode 1 versus Mode 2 requirements based on whether transmit and receive directions need independent time slot mapping. Verify that the system clock frequencies align with the specified BCLK period limits to ensure correct counter operation.

Telecom Part Context

The TP3155 is part of the National Semiconductor COMBO family ecosystem, specifically engineered to manage timing for synchronous digital telephony architectures. It serves as a bridge between the central processing logic and the audio codec filters, ensuring data alignment across multiple channels in high-density communication hardware.

Telecom Replacement Considerations

No direct public substitute part numbers are documented for this specific legacy component. Designers should evaluate modern programmable logic devices or updated synchronization ICs from the same manufacturer if pin compatibility is not strictly required.

Telecom FAQ

How does the MODE input affect the TP3155N operation?

Connecting the MODE pin to VCC selects Mode 1, allowing independent transmit and receive time slot assignments. Connecting it to GND selects Mode 2, which assigns all outputs relative to the transmit sync signal.

What is the function of the TSX output?

The TSX output is an open-drain signal that pulls low during any active transmit time slot. It can be wire-ANDed with other TSACs to control the TRI-STATE enable of a line driver.

How is the time slot assignment updated?

An 8-bit control word is clocked into the DC input while CS is low. The new assignment transfers to the register on the high-going transition of the CS signal.