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PG001M
PARALLEL-TO-SERIAL DATA CONVERTER
The PG001M CMOS IC converts parallel-data signals from a lowcost, 8-bit microprocessor or microcontroller into a serial-data format compatible with the SLA7042M and SLA7044M power multi-chip modules to drive unipolar PWM, high-current stepper motors. The converter provides for five basic modes of operation: 1) normal, two-phase, full step (100% torque vector), 2) two-phase 'boosted' torque (141% torque vector), 3) half-step, constant torque operation (using a 2-1-2 output switching), 4) quarter-stepping utilizing ratioed currents for constant torque, and 5) microstepping (1/8th steps) for quiet, smooth, resonance-free motor performance. The PG001M is supplied in a low-cost 16-pin dual in-line plastic package. It is rated for continuous operation over the temperature range of -20C to +85C.
Data Sheet 26112
RESET CLOCK IN CCW/CW NOT USABLE NOT USABLE MODE SELECT. .1 MODE . SELECT. 2 GROUND
1 2
V DD
16 15
CONTROL SUPPLY VECTOR CONTROL CLOCK OUT STROBE NO CONNECT. SERIAL DATA A SERIAL DATA B MONITOR
PARALLEL-TO-SERIAL
3 4 5 6 7 8
CONTROL LOGIC
14
CONVERTER
13 12 11 10 9
Dwg. PK-009
ABSOLUTE MAXIMUM RATINGS Supply Voltage, VDD .................... 7.0 V Input Voltage Range, VI ................ -0.5 V to VDD + 0.5 V Input Current, II ....................... 10 mA Output Voltage Range, VO ............... -0.5 V to VDD + 0.5 V Output Current, IO ................... 15 mA Operating Temperature Range, TA .......................... -20C to +85C Storage Temperature Range, TS ........................ -40C to +150C
CAUTION: CMOS devices have input static protection but are susceptible to damage if exposed to extremely high static electrical charges.
FEATURES
s Intended For Use With SLA7042M or SLA7044M Microstepping, Unipolar PWM, High-Current Motor Drivers s Supports Five Stepper-Motor Operating Modes s P-Compatible Inputs
Always order by complete part number, PG001M .
TM
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
FUNCTIONAL BLOCK DIAGRAM
CONTROL SUPPLY
MODE SELECT
2
7
SET MODE SELECTOR
V DD
16
MODE SELECT 1 6
PARALLEL-TO-SERIAL
CONVERTER
LOGIC
VECTOR 15 CONTROL MONITOR
9
SEQUENCING
a b c PHASE
10 SERIAL DATA 11 SERIAL DATA
B
A NO (INTERNAL) 12 CONNECTION
13 STROBE 14 CLOCK
NOT USABLE
5 4
OUT
CCW/CW CLOCK IN
3 2 1 8
UP-DOWN COUNTER OSC.
RESET
GROUND
Dwg. FK-009A
TRUTH TABLE
PG001M Motor Excitation Full Step Inputs VC H L Half Step 1/4 Step 1/8 Step X X X MS1 L L H L H MS2 L L L H H 0 0% - - s s s SLA7042/44M Output Sequence & PWM Current 1 20% - - - - s 2 3 4 5 6 7 Motor Torque 141% 100% 100% 100% 100%
40% 55.5% 71.4% 83% - - - s s - - - - s - s s s s - - - - s
91% 100% - - - s s s - s s s
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright (c) 1998, Allegro MicroSystems, Inc.
TM
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
ELECTRICAL CHARACTERISTICS at TA = +25C, VDD = 5 V (unless otherwise noted).
Characteristic Supply Voltage Output Voltage Input Current Input Voltage Symbol VDD VOH VOL IIH IIL VIH VIL Vhys fosc td(CIH-COH) td(CIL-SL) tr tf tckH tckL ci IDD
4.5 s 0.5 s
Test Conditions Operating IO = -3 mA IO = 3 mA VI = 5 V VI = 0 V
Min. 4.5 4.5 - - - 3.5 0 - -
Limits Typ. Max. - 5.5 4.6 0.3 - - - - 1.0 1.5 50 430 20 20 - - 5.0 350 - 0.4 1.0 -1.0 5.0 1.5 - - 100 550 - - - - 10 450
Units V V V A A V V V MHz ns ns ns ns s s pF A
Internal Oscillator Freq. Delay Time Output Switching Time CLOCKIN Pulse Width Input Capacitance Supply Current
CLKIN to CLKOUT rising edges CLKIN to STROBE falling edges CL = 15 pF, 10% to 90% CL = 15 pF, 90% to 10%
- - - - 4.5 0.5
VDD = 5.5 V
- -
CLOCK IN
100 ns
100 ns
RESET
PG001M Input Signals Timing
MODE SELECT CCW/CW
100 ns
VECTOR CONTROL
Dwg. WK-005
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
PHASE
CLOCKOUT
STROBE SERIAL DATA A FULL STEP 100% 1/8 STEP 100% 1/4 STEP 91% 3/8 STEP 83% 1/2 STEP 71.4% 5/8 STEP 55.5% 3/4 STEP 40% 7/8 STEP 20% FULL STEP 0% SERIAL DATA B
X
LSB
1
1
MSB
1
0%
X
0
0
0
X
1
1
1
20%
X
1
0
0
X
0
1
1
40%
X
0
1
0
X
1
0
1
55.5%
X
1
1
0
X
0
0
1
71.4%
X
0
0
1
X
1
1
0
83%
X
1
0
1
X
0
1
0
91%
X
0
1
1
X
1
0
0
100%
X
1
1
1
X
0
0
0
100%
X
1
1
1
FULL STEP
(141% TORQUE)
X
1
1
1
100%
X
1
1
1
100%
Dwg. WK-007
CLOCK, STROBE, and SERIAL DATA Outputs for Microstepping
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
TM
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
PG001M DESCRIPTION AND OPERATION
The PG001M is a CMOS step-motor control IC that converts parallel-input signals from a microprocessor (P, or microcontroller, C) to the serial-input data format required for control of an SLA7042M or SLA7044M microstepping, unipolar PWM, high-current motor driver. This control IC offers five basic modes of motor operation: 1) normal 2-phase, full-step (100% torque vector); 2) 2-phase, full-step 'boosted' torque (141% vector); 3) 1/2-step, constant torque operation (i.e., 2-1-2 switching); 4) 1/4-step operation with current-ratioed constant torque; and 5) smooth microstepping operation (1/8th step) for resonance-free motor performance (constant torque with eight output current ratios). Three inputs (VC, MS1, and MS2) control these five operational modes (as shown in figure 1); this enables designers to change the drive method during movement to realize optimal performance. Initially, at start-up, the high-torque mode can provide 141% torque (the resulting vector of both motor windings at 100% current). This enhances rapid acceleration (and deceleration). Switching to quarter-stepping or microstepping (after initial, startup acceleration) offers smooth, resonance-free operation during the ramp-up interval. The transition to quarter- or microstepping should occur before the increasing step rate approaches the motor resonance frequency (usually 100 to 200 Hz). The modes of operation and current-control truth table are listed on page 2; and there are two full-step, 2-phase (2-2) operating modes. The VECTOR CONTROL input (VC) can only be changed when MONITOR (MO, a readback pin) is LOW and the PG001M is operating in the full-step mode. Starting (or stopping) the step motor with VC HIGH delivers the highest torque (141%) from the motor, and is the extension of two outputs ON at 71.4%. This 'half-step' rotor position corresponds to the state when MO is LOW, and switching the control inputs to another operating mode is allowed. The PG001M accepts logic signals from the P and converts these into the proper serial-data format required to control the serial-data input lines of the SLA7042M or SLA7044M microstepping power modules. The five
A AB AB
B
B
AB A ONE-PHASE, FULL-STEP MODE
(WITHOUT PG001M)
AB
TWO-PHASE, FULL-STEP MODE
(MS1 = L, MS2 = L, VC = L)
AB
AB AB
A AB
B
B
AB AB AB
AB
TWO-PHASE, FULL-STEP MODE MAXIMUM TORQUE (141%)
(MS1 = L, MS2 = L, VC = H)
A 1/2-STEP MODE CONSTANT TORQUE
(MS1 = H, MS2 = L, VC = X)
A AB AB AB
A AB
B
B
B
B
AB A 1/4-STEP MODE
AB
AB A 1/8-STEP MODE
AB
(MS1 = L, MS2 = H, VC = X)
(MS1 = H, MS2 = H, VC = X)
Dwg. OP-005
NOTE - Mode change only allowed at half-step positions (refer to upper right figure).
Figure 1 -- Current/Displacement Vectors control inputs determine the various modes of operation. The CLOCKOUT, SERIAL DATAA, SERIAL DATAB, and STROBE to the SLA7042/44M are synchronized to the CLOCKIN of the PG001M; and the CLOCKIN frequency is eight times the step rate (more to follow on the signal/ timing relationships). The internal logic and oscillator combine to convert the parallel input signals to 'bursts' of serial data from the
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
CLOCKOUT, SERIAL DATAA, SERIAL DATAB, and STROBE. In the full-step modes the clock, data, and strobe pulses are 1/8 the input clock rate; while half-step operation produces 'bursts' at 1/4 the input clock rate. Further, quarter-step mode signals correspond to 1/2 the input clock frequency; while during microstepping the signal 'bursts' equal the input clock rate. Hence, the step rate is always 1/8th the input clock frequency, regardless of the operating mode. Obviously, the clock rate increases while accelerating, becomes constant during slewing, and decreases as the step motor and load are decelerating. Microstepping Operation Figures 1 and 2 illustrate the incremental eight step divisions provided while microstepping. The 3-bit sequence from 0 through 8 provides smooth, constant-torque operation that is delivered to the motor/load by the SLA7042M or SLA7044M power multi-chip modules. The circle in figure 1 and the arc in figure 2 represent the constant-torque vectors. Slight discrepancies are evident when examining the vector 'arrows'. The disparity is insignificant, and will not affect smooth, resonance-free motion. However, it may affect realizing accurate and precise intermediate positioning. Subdividing steps into
A 100 91 MAXIMUM FULL-STEP
eight distinct, exact positions is often very challenging. Clearly, variation in the phase currents affects rotor displacement, and is a very crucial factor in resolving accurate, intermediate step divisions. Another critical factor to realizing precise, repeatable step subdivisions pertains to the selection and evaluation of the step motor. The better motors exhibit uniformly spaced positioning characteristics. However, torque vs displacement characteristics vary (often greatly). Usually, precise step subdivisions require motors designed for microstepping. An 'Integrated' Microstepping Design The combination of CMOS controller IC and microstepping power module is depicted in figure 3. The P provides the needed logic signals that reset the counter, control rotor direction, determine the operating mode, and change the current/torque vector (during full-step, 2-phase operation). The sequencing logic provides a 'readback' signal (the MO output) that switches LOW at the half-step position when the microcontroller can shift control modes and not incur oscillation/vibration problems. The mode change is allowed at the 45 vector, half-step position shown in figure 2. In addition to the 45 AB vector, three other halfstep vectors occur during stepping: AB at 135, AB at 225, and AB at 315 (figure 1). These current vectors correspond to the half-step positions in four quadrants, and four 2-phase, full steps of rotation. The Parallel-to-Serial Conversion Perhaps the greatest system advantage for designers is the simplification of software. Controlling and operating the SLA7042/44M power multi-chip modules directly would require programming the system P to provide and update serial data to both the A and B inputs, and signals to the clock and strobe inputs that control the A and B sections of the driver. Although designs utilizing the CMOS control IC require seven I/O lines, the software program will be simpler and shorter. The system P provides logic signals that control RESET, CCW/CW (direction), MODE SELECT1, MODE SELECT2, VECTOR CONTROL, and read the MONITOR return. Only the CLOCK input is a 'dynamic', constantly switching signal from the system control I/O.
TORQUE (141%)
10
1/8 ST
83
EP
0%
P
C
STE
O N ST
1/4
P
AN
71.4
ST E
T TO
CURRENT IN PER CENT
3/8
R Q
EP
U
ST
E
55.5
1/
2
5/8
40
ST
EP
3/4
STE
P
20
7/8 ST
EP
B 20 A
FULL STEP B 40 55.5 71.4 CURRENT IN PER CENT 83 91 100
Dwg. GK-020
Figure 2 -- Current/Displacement Vectors
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
TM
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
+5 V
V BB
A CONTROL SUPPLY A B CLOCK
A
B OUT
B
CLOCK IN CCW/CW
V DD
REF/ENABLE A B
SLA7042M or SLA7044M
GND B R SA R SB
A B
MODE SELECT1
PG001M
STROBE
A B
P
MODE SELECT2 RESET VECTOR CONTROL
SERIAL DATA SERIAL DATA
A B
MONITOR GND
GND A
Dwg. EK-014A
Figure 3 -- Typical 'Integrated' Microstepping System Depicted in figure 4 are the 'front-end' I/O signals (from RESET to VECTOR CONTROL), converted signals from the controller IC to the microstepping power module (CLOCKOUT, SERIAL DATAA, SERIAL DATAB, and STROBE), plus the MONITOR (readback) to the microcontroller. Finally, the power multi-chip module current ratios are illustrated (OUTA and OUTB). As shown, initially the counter is reset, and then the motor is operating in quarter-step mode; then MS2 is switched while MO is LOW. The two steps following are full-step (100% torque vector). The final (fourth quadrant) portion of figure 4 is the maximum (141%) torque mode, after VECTOR CONTROL has been switched from LOW to HIGH. Three of the five operational modes are shown, and none require the P to continually update the clock, serial-data input, or strobe to the SLA7042/44M module. The microstepping operation is illustrated in figure 5. Initially the counter is reset, and with both MODE SELECTs HIGH the controller is furnishing clock, serial data, and strobe logic signals for 1/8th step increments. After the RESET pulse, the first (two) full-steps in the microstepping sequence, MS1 is switched LOW and the control IC shifts into the 1/4-step mode. It becomes very apparent that any microstepping directly from a P to the SLA7042/44M module 'burdens' the P, complicates the software, and might entail a 'dedicated' microcontroller in many motion-control systems. The PG001M controller IC precludes loading a P with direct serial-data signals to the power multi-chip module. Because the step motor is updated at eight times the step rate, this CMOS IC both simplifies software and eliminates loading a system microprocessor with 'housekeeping' control of step motors. As illustrated in figures 4 and 5, the controller IC eliminates the requirement to program the system for the various modes of operation and the continual updating of the serial-data signals to the power multi-chip module. NOTE -- In figures 4 and 5, the clock frequency is constant during the few steps of operation that are shown and half-step operation is not included.
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
RESET
CLOCK IN
CCW/CW
MODE SELECT1 1/4-STEP MODE FULL-STEP MODE MODE SELECT 2 FULL-STEP MODE MAXIMUM TORQUE (141%)
VECTOR CONTROL
CLOCK OUT
71.4 40 0 40 71.4 71.4 71.4 100
SERIAL DATA A
71.4 91 100 91 71.4 71.4 71.4 100
SERIAL DATAB
STROBE
MONITOR
PER CENT OUT
71.4
40
0
-40
-71.4
-71.4
71.4
100
A FIRST QUADRANT SECOND QUADRANT THIRD QUADRANT FOURTH QUADRANT FIRST QUADRANT
PER CENT OUT
71.4
91
100
91
71.4
-71.4
-71.4
100
B
Dwg. WK-006
Figure 4 -- Quarter-Step, Full-Step, and High-Torque Full-Step
Because the parallel-to-serial conversion requires six 'static' logic signals plus a 'dynamic' (clock) input, the addition of latches between the P and five of the controller IC inputs permits use on a bus. Latching the five signals to CCW/CW, MS1, MS2 , RESET, and VC frees these five I/O lines for other operations by the microcontroller. Even at extremely high step rates (>5 kHz), updating the PG001M input data requires an infinitesimal percentage of the P's I/O and control operations.
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
TM
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
RESET
CLOCK IN
CCW/CW
MODE SELECT1
1/8-STEP MODE 1/4-STEP MODE
MODE SELECT 2
VECTOR CONTROL
CLOCK OUT
71.4 55.5 40 20 0 20 40 55.5 71.4 83 91 100 100 100 91 83 71.4 40 0 40 71.4 91 100 91 71.4
SERIAL DATA
A
71.4 83 91 100 100 100 91 83 71.4 55.5 40 20 0 20 40 55.5 71.4 91 100 91 71.4 40 0 40 71.4
SERIAL DATAB
STROBE
MONITOR
PER CENT OUT
71.4
55.5
40
20
0
-20
-40
-55.5
-71.4
-83
-91
-100
-100
-100
-91
-83
-71.4
-40
0
40
71.4
91
100
91
71.4
A
FIRST QUADRANT PER CENT OUT
71.4 83 91 100 100 100 91
SECOND QUADRANT
83 71.4 55.5 40 20 0 -20 -40
THIRD QUADRANT
-55.5 -71.4 -91 -100 -91
FOURTH QUADRANT
-71.4 -40 0 40
FIRST QUADRANT
71.4
B
Dwg. WK-006-1
Figure 5 -- Microstepping (1/8th-Step) and Quarter-Step Modes
One technique to free P I/O lines for shared functions is depicted in figure 6. The I/O lines required (without latches) are then transformed into three 'dedicated' logic inputs; a STROBE is added, and CLOCK and MONITOR retained. CLOCK, RESET, MODE SELECT1, MODE SELECT2, and VECTOR CONTROL now connect to a bus.
The clock input frequency limit is derived from the figure on page 3. The minimum period for the clock pulse HIGH is 4.5 s, plus a minimum LOW interval of 0.5 s; this limits the upper clock frequency to 200 kHz. Updating the operating mode of the controller IC requires only one clock period (5 s), and the five I/O lines on the bus remain unchanged until a signal is required to change the operating mode, reverse direction, vary torque, etc.
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
V CC +5 V
CLOCK IN V CCW/CW CC MODE SELECT1
V DD CLOCK
LATCHES (5)
MODE SELECT2 RESET VECTOR CONTROL
PG001M
STROBE
P
SERIAL DATA A SERIAL DATA B
STROBE GND MONITOR GND
Dwg. EK-014-1
Figure 6 -- A Latched Input-Bus Configuration
At start-up, reseting the counter adds only another clock interval (per figures 4 and 5). During high-speed slewing, the P is only occupied with sending clock signals and monitoring the readback (MO). Hence, of a 200 s interval, with a slewing rate of 5 kHz, only 5 s is required to provide the clock input. At slower, more typical step rates, 5 s becomes an insignificant burden on the P controlling the stepping motor. Other techniques to decrease and unburden the essential P I/O lines and control logic are viable. Utilizing an 8-bit shift register (serial-to-parallel conversion) between the P and the controller IC further reduces the I/O lines, and HCMOS logic provides serial-data entry at 20 MHz (vs <200 kHz). Such a design could further decrease the interval required to update the step-motor operation and reduce the I/O lines on the bus.
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
TM
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
Dimensions in Inches
(controlling dimensions)
16 9 0.014 0.008
0.430 0.280 0.240
MAX
0.300
BSC
1 0.070 0.045
0.100 0.775 0.735
BSC
8 0.005
MIN
0.210
MAX
0.015
MIN
0.150 0.115 0.022 0.014
Dwg. MA-001-16A in
Dimensions in Millimeters
(for reference only)
16 9 0.355 0.204
10.92 7.11 6.10
MAX
7.62
BSC
1 1.77 1.15
2.54 19.68 18.67
BSC
8 0.13
MIN
5.33
MAX
0.39
MIN
3.81 2.93 0.558 0.356
Dwg. MA-001-16A mm
NOTES:1. Lead thickness is measured at seating plane or below. 2. Lead spacing tolerance is non-cumulative. 3. Exact body and lead configuration at vendor's option within limits shown.
PG001M PARALLEL-TO-SERIAL DATA CONVERTER
The products described here are manufactured in Japan by Sanken Electric Co., Ltd. for sale by Allegro MicroSystems, Inc. Sanken Electric Co., Ltd. and Allegro MicroSystems, Inc. reserve the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the design of their products. The information included herein is believed to be accurate and reliable. However, Sanken Electric Co., Ltd. and Allegro MicroSystems, Inc. assume no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use.
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
TM

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