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LM628, LM629

www.ti.com

SNVS781C –JUNE 1999–REVISED MARCH 2013

LM628/LM629 Precision Motion Controller

Check for Samples: LM628, LM629

FEATURES

DESCRIPTION

The LM628/LM629 are dedicated motion-control

• 32-bit Position, Velocity, And Acceleration

processors designed for use with a variety of DC and

Registers

brushless DC servo motors, and other

• Programmable Digital PID Filter with 16-bit

servomechanisms which provide a quadrature

Coefficients

incremental position feedback signal. The parts

perform the intensive, real-time computational tasks

• Programmable Derivative Sampling Interval

required for high performance digital motion control.

• 8- or 12-bit DAC Output Data (LM628)

The host control software interface is facilitated by a

• 8-bit Sign-magnitude PWM Output Data

high-level command set. The LM628 has an 8-bit

(LM629)

output which can drive either an 8-bit or a 12-bit

DAC. The components required to build a servo

• Internal Trapezoidal Velocity Profile Generator

system are reduced to the DC motor/actuator, an

• Velocity, Target Position, and Filter

incremental encoder, a DAC, a power amplifier, and

Parameters may be Changed During Motion

the LM628. An LM629-based system is similar,

• Position and Velocity Modes of Operation

except that it provides an 8-bit PWM output for

directly driving H-switches. The parts are fabricated in

• Real-time Programmable Host Interrupts

NMOS and packaged in a 28-pin dual in-line package

• 8-bit Parallel Asynchronous Host Interface

or a SOIC-24 package (LM629 only). Both 6 MHz and

• Quadrature Incremental Encoder Interface with

8 MHz maximum frequency versions are available

Index Pulse Input

with the suffixes -6 and -8, respectively, used to

designate the versions. They incorporate an SDA

• Available in a 28-pin Dual In-line Package or a

core processor and cells designed by SDA.

SOIC-24 Package (LM629 Only)

Figure 1. Block Diagram

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (35 pages)

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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 LM628/LM629 Precision Motion Controller Check for Samples: LM628, LM629 FEATURES 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.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com Connection Diagrams LM628N LM629N LM629M *Do not connect. Figure 2. See Package Number DW or N These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) Voltage at Any Pin with −0.3V to +7.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 DC Electrical Characteristics (VDD and TA per Operating Ratings; fCLK = 6 MHz) Symbol IDD Parameter Tested Limits Conditions Supply Current Min Outputs Open Max 110 Units mA INPUT VOLTAGES VIH Logic 1 Input Voltage VIL Logic 0 Input Voltage IIN Input Currents 2.0 0 ≤ VIN ≤ VDD −10 2.4 V 0.8 V 10 μA OUTPUT VOLTAGES VOH Logic 1 IOH = −1.6 mA VOL Logic 0 IOL = 1.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 Figure 4. Clock and Reset Timing Figure 5. Status Byte Read Timing Figure 6.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com Figure 7. Data Word Read Timing Figure 8.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 Pinout Description (See Connection Diagrams) Pin numbers for the 24-pin surface mount package are indicated in parentheses. Pin 1 (17), Index (IN) Input: Receives optional index pulse from the encoder. Must be tied high if not used. The index position is read when Pins 1, 2, and 3 are low. Pins 2 and 3 (18 and 19), Encoder Signal (A, B) Inputs: Receive the two-phase quadrature signals provided by the incremental encoder.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com Pin 27 (15), Reset (RST) Input: Active-low, positive-edge triggered, resets the LM628 to the internal conditions shown below. Note that the reset pulse must be logic low for a minimum of 8 clock periods. Reset does the following: 1. Filter coefficient and trajectory parameters are zeroed. 2. Sets position error threshold to maximum value (7FFF hex), and effectively executes command LPEI. 3. The SBPA/SBPR interrupt is masked (disabled). 4.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 THEORY OF OPERATION INTRODUCTION The typical system block diagram (See Figure 1) illustrates a servo system built using the LM628. The host processor communicates with the LM628 through an I/O port to facilitate programming a trapezoidal velocity profile and a digital compensation filter. The DAC output interfaces to an external digital-to-analog converter to produce the signal that is power amplified and applied to the motor.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com Figure 11. Typical Velocity Profiles VELOCITY PROFILE (TRAJECTORY) GENERATION The trapezoidal velocity profile generator computes the desired position of the motor versus time. In the position mode of operation, the host processor specifies acceleration, maximum velocity, and final position.
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LM628, LM629 www.ti.com and SNVS781C – JUNE 1999 – REVISED MARCH 2013 P = 2000 * desired number of revolutions P = 2000 * 100 revs = 200,000 counts (value to load) P (coding) = 00030D40 (hex code written to LM628) let V = velocity (units = counts/sample) let T = sample time (seconds) = 341 μs (with 6 MHz clock) let C = conversion factor = 1 minute/60 seconds then V = R * T * C * desired rpm and V = 2000 * 341E−6 * 1/60 * 600 rpm V = 6.82 counts/sample V (scaled) = 6.82 * 65,536 = 446,955.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com In operation, the filter algorithm receives a 16-bit error signal from the loop summing-junction. The error signal is saturated at 16 bits to ensure predictable behavior.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 Figure 12. PWM Output Signal Format (Sign output (pin 18) not shown) Table 2.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com User Command Set GENERAL The following paragraphs describe the user command set of the LM628. Some of the commands can be issued alone and some require a supporting data structure. As examples, the command STT (STarT motion) does not require additional data; command LFIL (Load FILter parameters) requires additional data (derivative-term sampling interval and/or filter parameters).
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 DFH COMMAND: DEFINE HOME Command Code: 02 Hex Data Bytes: None Executable During Motion: Yes This command declares the current position as “home”, or absolute position 0 (Zero). If DFH is executed during motion it will not affect the stopping position of the on-going move unless command STT is also executed.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com LPES COMMAND: LOAD POSITION ERROR FOR STOPPING Command Code: 1A Hex Data Bytes: Two Data Range: 0000 to 7FFF Hex Executable During Motion: Yes Instruction LPES is essentially the same as command LPEI above, but adds the feature of turning off the motor upon detecting excessive position error. The motor drive is not actually switched off, it is set to half-scale, the offset-binary code for zero.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 Table 3.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com The derivative-term sampling interval is also programmable via this command. After writing the command code, the first two data bytes that are written specify the derivative-term sampling interval and which of the four filter parameters is/are to be written via any forthcoming data bytes. The first byte written is the more significant.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 Trajectory Control Commands The following two LM628 user commands are used for setting the trajectory control parameters (position, velocity, acceleration), mode of operation (position or velocity), and direction (velocity mode only) as required to describe a desired motion or to select the mode of a manually directed stop, and to control the timing of these system changes.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com Table 6. Trajectory Control Word Bit Allocation (continued) Bit Position Function Bit 1 Position Will Be Loaded Bit 0 Position Data Is Relative Bit 12 determines the motor direction when in the velocity mode. A logic one indicates forward direction. This bit has no effect when in position mode. Bit 11 determines whether the LM628 operates in velocity mode (Bit 11 logic one) or position mode (Bit 11 logic zero).
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 The STT command is used to execute the desired trajectory, the specifics of which have been programmed via the LTRJ command. Synchronization of multi-axis control (to within one sample interval) can be arranged by loading the required trajectory parameters for each (and every) axis and then simultaneously issuing a single STT command to all axes.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com Bit 3, the index-pulse acquired interrupt flag, is set to logic one when an index pulse has occurred (if command SIP had been executed) and indicates that the index position register has been updated. The flag is functional independent of the host interrupt mask status. Bit 3 is cleared by command RSTI.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 Bit 13, the UDF-executed flag, is set to logic one when the UDF command is executed. Because bit 13 is cleared at the end of the sampling interval in which it has been set, this signal is very short-lived and probably not very profitable for monitoring. Bit 12, the forward direction flag, is meaningful only when the LM628 is in velocity mode.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com RDDV COMMAND: READ DESIRED VELOCITY Command Code: 07 Hex Bytes Read: Four Data Range: C0000001 to 3FFFFFFF Executable During Motion: Yes This command reads the integer and fractional portions of the instantaneous desired (current temporal ) velocity, as used to generate the desired position profile. The bytes are read in most-to-least significant order.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 TYPICAL HOST COMPUTER/PROCESSOR INTERFACE The LM628 is interfaced with the host computer/processor via an 8-bit parallel bus. Figure 13 shows such an interface and a minimum system configuration. As shown in Figure 13, the LM628 interfaces with the host data, address and control lines. The address lines are decoded to generate the LM628 CS input; the host address LSB directly drives the LM628 PS input.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com Note: Figure 13. Host Interface and Minimum System Configuration Figure 14.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 *DAC offset must be adjusted to minimize DAC linearity and monotonicity errors. See text. Figure 15. Interfacing a 12-Bit DAC and LM628 Figure 16.
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LM628, LM629 SNVS781C – JUNE 1999 – REVISED MARCH 2013 www.ti.com Figure 17. PWM Drive for Brush/Commutator Motors Figure 18.
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LM628, LM629 www.ti.com SNVS781C – JUNE 1999 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision B (March 2013) to Revision C • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com (4) 11-Apr-2014 There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM629MX-8/NOPB Package Package Pins Type Drawing SOIC DW 24 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 1000 330.0 24.4 Pack Materials-Page 1 10.8 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 15.9 3.2 12.0 24.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM629MX-8/NOPB SOIC DW 24 1000 367.0 367.0 45.
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