LM629N-8/NOPB National Semiconductor, LM629N-8/NOPB Datasheet - Page 8

• Manufacturer Part Number: LM629N-8/NOPB
• Description: IC CONTROLLER PREC MOTION 28-DIP
• Manufacturer: National Semiconductor

Specifications of LM629N-8/NOPB

• Applications: DC Motor Controller, Servo
• Number Of Outputs: 1
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Through Hole
• Package / Case: 28-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Load: -
• Other names: *LM629N-8; *LM629N-8/NOPB; LM629N-8

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Position Range
Velocity Range
Acceleration Range
Motor Drive Output
Operating Modes
Feedback Device
Pinout Description
within 1.5 ms. If the status word has not changed from hex
“00” to “84” or “C4” within 1.5 ms, perform another reset and
repeat the above steps. To be certain that the reset was
properly performed, execute a RSTI command. If the chip
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 facili-
tate programming a trapezoidal velocity profile and a digital
compensation filter. The DAC output interfaces to an exter-
nal digital-to-analog converter to produce the signal that is
power amplified and applied to the motor. An incremental
encoder provides feedback for closing the position servo
loop. The trapezoidal velocity profile generator calculates the
required trajectory for either position or velocity mode of
operation. In operation, the LM628 subtracts the actual po-
sition (feedback position) from the desired position (profile
generator position), and the resulting position error is pro-
cessed by the digital filter to drive the motor to the desired
position. Table 1 provides a brief summary of specifications
offered by the LM628/LM629:
POSITION FEEDBACK INTERFACE
The LM628 interfaces to a motor via an incremental encoder.
Three inputs are provided: two quadrature signal inputs, and
an index pulse input. The quadrature signals are used to
−1,073,741,824 to 1,073,741,823 counts
0 to 1,073,741,823/2
counts/sample
0 to 1,073,741,823/2
resolution of 1/2
LM628: 8-bit parallel output to DAC, or 12-bit multiplexed output to DAC
LM629: 8-bit PWM sign/magnitude signals
Position and Velocity
Incremental Encoder (quadrature signals; support for index pulse)
(Continued)
FIGURE 8. 12-Bit Multiplexed Output Timing
TABLE 1. System Specifications Summary
16
counts/sample/sample
16
16
counts/sample; ie, 0 to 16,383 counts/sample, with a resolution of 1/2
counts/sample/sample; ie, 0 to 16,383 counts/sample/sample, with a
8
has reset properly, the status byte will change from hex “84”
or “C4” to hex “80” or “C0”. If this does not occur, perform
another reset and repeat the above steps.
Pin 28 (16), Supply Voltage (V
(+5V).
keep track of the absolute position of the motor. Each time a
logic transition occurs at one of the quadrature inputs, the
LM628 internal position register is incremented or decre-
mented accordingly. This provides four times the resolution
over the number of lines provided by the encoder. See
Figure 9. Each of the encoder signal inputs is synchronized
with the LM628 clock.
The optional index pulse output provided by some encoders
assumes the logic-low state once per revolution. If the
LM628 is so programmed by the user, it will record the
absolute motor position in a dedicated register (the index
register) at the time when all three encoder inputs are logic
low.
If the encoder does not provide an index output, the LM628
index input can also be used to record the home position of
the motor. In this case, typically, the motor will close a switch
which is arranged to cause a logic-low level at the index
input, and the LM628 will record motor position in the index
register and alert (interrupt) the host processor. Permanently
grounding the index input will cause the LM628 to malfunc-
tion.
DD
): Power supply voltage
00921910
16