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LM629

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LM628/LM629

Precision Motion Controller

General Description

The LM628/LM629 are dedicated motion-control processors

designed for use with a variety of DC and brushless DC

servo motors, and other servomechanisms which provide a

quadrature incremental position feedback signal. The parts

perform the intensive, real-time computational tasks required

for high performance digital motion control. The host control

software interface is facilitated by a high-level command set.

The LM628 has an 8-bit output which can drive either an

8-bit or a 12-bit DAC. The components required to build a

servo system are reduced to the DC motor/actuator, an in-

cremental encoder, a DAC, a power amplifier, and the

LM628. An LM629-based system is similar, except that it

provides an 8-bit PWM output for directly driving H-switches.

The parts are fabricated in NMOS and packaged in a 28-pin

dual in-line package or a 24-pin surface mount package

(LM629 only). Both 6 MHz and 8 MHz maximum frequency

versions are available with the suffixes -6 and -8, respec-

tively, used to designate the versions. They incorporate an

SDA core processor and cells designed by SDA.

Features

n 32-bit position, velocity, and acceleration registers

n Programmable digital PID filter with 16-bit coefficients

n Programmable derivative sampling interval

n 8- or 12-bit DAC output data (LM628)

n 8-bit sign-magnitude PWM output data (LM629)

n Internal trapezoidal velocity profile generator

n Velocity, target position, and filter parameters may be

changed during motion

n Position and velocity modes of operation

n Real-time programmable host interrupts

n 8-bit parallel asynchronous host interface

n Quadrature incremental encoder interface with index

pulse input

n Available in a 28-pin dual in-line package or a 24-pin

surface mount package (LM629 only)

TRI-STATE

is a registered trademark of National Semiconductor Corporation.

DS009219-1

FIGURE 1. Block Diagram

November 1999

LM628/LM629 Precision Motion Controller

AC Electrical Characteristics (Continued)

and T

per Operating Ratings; f

CLK

6 MHz; C

LOAD

50 pF; Input Test Signal t

10 ns)

Timing Interval T

Tested Limits Units

Min Max

STATUS BYTE READ TIMING (See

Figure 4

)

Chip-Select Setup/Hold Time T7 0 ns

Port-Select Setup Time T8 30 ns

Port-Select Hold Time T9 30 ns

Read Data Access Time T10 180 ns

Read Data Hold Time T11 0 ns

RD High to Hi-Z Time

T12 180 ns

COMMAND BYTE WRITE TIMING (See

Figure 5

)

Chip-Select Setup/Hold Time T7 0 ns

Port-Select Setup Time T8 30 ns

Port-Select Hold Time T9 30 ns

Busy Bit Delay T13 (Note 3) ns

WR Pulse Width

T14 100 ns

Write Data Setup Time T15 50 ns

Write Data Hold Time T16 120 ns

DATA WORD READ TIMING (See

Figure 6

)

Chip-Select Setup/Hold Time T7 0 ns

Port-Select Setup Time T8 30 ns

Port-Select Hold Time T9 30 ns

Read Data Access Time T10 180 ns

Read Data Hold Time T11 0 ns

RD High to Hi-Z Time

T12 180 ns

Busy Bit Delay T13 (Note 3) ns

Read Recovery Time T17 120 ns

DATA WORD WRITE TIMING (See

Figure 7

)

Chip-Select Setup/Hold Time T7 0 ns

Port-Select Setup Time T8 30 ns

Port-Select Hold Time T9 30 ns

Busy Bit Delay T13 (Note 3) ns

WR Pulse Width

T14 100 ns

Write Data Setup Time T15 50 ns

Write Data Hold Time T16 120 ns

Write Recovery Time T18 120 ns

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when operating

the device beyond the above Operating Ratings.

Note 2: When operating at ambient temperatures above 70˚C, the device must be protected against excessive junction temperatures. Mounting the package on a

printed circuit board having an area greater than three square inches and surrounding the leads and body with wide copper traces and large, uninterrupted areas of

copper, such as a ground plane, suffices. The 28-pin DIP (N) and the 24-pin surface mount package (M) are molded plastic packages with solid copper lead frames.

Most of the heat generated at the die flows from the die, through the copper lead frame, and into copper traces on the printed circuit board. The copper traces act

as a heat sink. Double-sided or multi-layer boards provide heat transfer characteristics superior to those of single-sided boards.

Note 3: In order to read the busy bit, the status byte must first be read. The time required to read the busy bit far exceeds the time the chip requires to set the busy