Texas Instruments LM628N-6/NOPB

Overview

LM628N-6/NOPB from Texas Instruments is a dedicated 32-bit precision motion controller IC for closed-loop DC and brushless DC servo systems, featuring programmable digital PID filtering, trapezoidal velocity profile generation, and quadrature encoder interface with index pulse support. It delivers 8-bit parallel DAC output, operates at up to 6 MHz clock frequency, and targets industrial positioning stages, CNC axes, and automated test equipment requiring deterministic real-time trajectory control.

For engineers reviewing the LM628N-6/NOPB datasheet, LM628N-6/NOPB pinout, LM628N-6/NOPB application, or LM628N-6/NOPB equivalent, key selection criteria include its 32-bit position/velocity/acceleration registers, 8-bit DAC output mode, 28-pin PDIP package, −40°C to +85°C operating range, and compatibility with incremental encoders delivering quadrature A/B and index signals.

Technical Context

The LM628N-6/NOPB implements an NMOS-based SDA core processor executing real-time motion control algorithms including trapezoidal trajectory generation and discrete-time PID compensation with programmable derivative sampling interval (2048/f_CLK to 65,536 μs). Its quadrature decoder provides 4× resolution enhancement over encoder line count and requires ≥8 clock periods per encoder state for valid capture.

It supports two DAC output configurations: latched 8-bit parallel (Pins 18–25) or multiplexed 12-bit (Pins 18–24 + strobe on Pin 25), with offset-binary coding (0x80 = zero torque). Host communication uses an 8-bit parallel asynchronous interface with chip-select (CS), port-select (PS), read (RD), and write (WR) controls, plus active-high host interrupt (HI) signaling.

Key Specifications

Pinout & Package

LM628N-6/NOPB is housed in a 28-pin plastic dual in-line package (PDIP) with 0.6-inch body width and through-hole mounting. Thermal performance relies on copper trace heat sinking via the lead frame; maximum power dissipation is 605 mW at T_A ≤ 85°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM628N-8/NOPB, LM628N-6/NOPB trades maximum clock speed for reduced EMI and lower power consumption while retaining full 32-bit motion control capability; compared with LM629N-6/NOPB, it provides analog-compatible DAC output essential for low-noise, high-resolution torque control in sensitive positioning systems.

Availability

LM628N-6/NOPB is available at Aetrix Electronics and suitable for industrial CNC positioning, automated test equipment, medical lab automation, and optical instrument positioning requiring stable component supply and long-term production continuity.

Supply support for LM628N-6/NOPB 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and high-reliability components for industrial, automotive, and communications markets.

The LM628N-6/NOPB belongs to TI's precision motion controller product line, designed specifically for deterministic real-time servo control in resource-constrained embedded systems using DC and brushless DC motors.

FAQ

What is the primary function of the LM628N-6/NOPB in a motion control system?

The LM628N-6/NOPB serves as a dedicated 32-bit motion controller IC that executes real-time trapezoidal trajectory generation and digital PID compensation for closed-loop DC and brushless DC servo systems. It accepts quadrature encoder feedback, computes position error, applies programmable filter coefficients, and outputs 8-bit DAC data to drive external amplifiers-offloading intensive motion math from the host processor and ensuring deterministic timing in the LM628N-6/NOPB.

Does the LM628N-6/NOPB support both 8-bit and 12-bit DAC output modes?

Yes, the LM628N-6/NOPB supports both output configurations via software command: PORT8 selects latched 8-bit parallel output on Pins 18–25, while PORT12 configures multiplexed 12-bit output using Pins 18–24 plus strobe on Pin 25. The 8-bit mode is default at reset (0x80 = zero torque); 12-bit mode requires external demultiplexing logic and is not enabled out-of-box in the LM628N-6/NOPB.

What is the maximum encoder signal frequency the LM628N-6/NOPB can reliably process?

At its rated 6 MHz clock frequency, the LM628N-6/NOPB requires a minimum of 8 clock periods per encoder state, resulting in a maximum reliable quadrature capture rate of 750 kHz. This corresponds to 3 million encoder state transitions per second (A/B edges combined), supporting high-resolution encoders on fast-moving axes without missing counts in the LM628N-6/NOPB.

How does the LM628N-6/NOPB handle homing and absolute position referencing?

The LM628N-6/NOPB uses its Index (IN) input (Pin 1) to capture absolute position upon detection of a logic-low index pulse from the encoder-provided simultaneously with low A and B signals. Alternatively, a mechanical switch can pull Pin 1 low to define a hardware home position, triggering an interrupt (SIP command) and storing the current position in the index register. This establishes repeatable absolute coordinates without battery-backed memory in the LM628N-6/NOPB.

Can the LM628N-6/NOPB update motion parameters while the motor is moving?

Yes, the LM628N-6/NOPB supports real-time parameter updates during motion for target position, velocity, and acceleration via LTRJ and STT commands. Trajectory changes take effect immediately within the next control cycle, enabling synchronized multi-axis moves, dynamic path correction, and responsive error recovery-all without halting motion or resetting the LM628N-6/NOPB.