copyright AA2020A, aa2820 bilevel step motor driver controller ics 910 e. orangefair lane anaheim, ca 92801 (714) 992-6990 fax (714) 992-0471 april 15, 2002 #l010010 copyright 1995 by anaheim automation. all rights reserved. no part of this publication may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language, in any form or by any means , ele ctronic, mechanical, magnetic, optical, chemical, manual, or otherwise , without the prior written permission of anaheim automation, 910 e. orangefai r lane, anaheim, ca 92801. disclaimer though every effort has been made to supply complete and accurat e information in this m anual, the contents are subject to change without notice or obligati on to inform the buyer. in no event will anaheim automation b e liable for direct, indirect, special, incidental, or consequential damages arising out of the use or inability to use the product or documentation. limited warranty all ana heim automation products are warranted against defects i n workmanship, materials and construction, when used under normal operatin g conditi ons and when used in accordance with specifications. this warranty shall be in effect for a period of twelve months from the date of purchase or ei ghteen months from the date of manufacture, whichever comes first . warranty provisions may be voided if the products are subjected to physical damage or abuse. anaheim a utomation will repair or replace at its option, any of its product s which hav e been found to be defective and are within the warranty period , pr ovided that the item is shipped freight prepaid, with rma (return materia l authorization), to anaheim automation's plant in anaheim, california.
1 2 figure 1: AA2020A dimensions. figure 2: aa2820 dimensions. description specifications the AA2020A and aa2820 are cmos integrated circuits that are ideally suite d for the design of 4-phase unipolar and bipolar step m otor drivers. these ic's can be used to design half-step and full-step bilevel type drivers. the basic function of these ics is to take input (i.e. clock and direction) signal s and turn them into appropriate phase signals that are used to drive outpu t transistors. in most applications, the end user simply adds a few component s alo ng with power transistors for the output stage. this results in low cost , compact, and reliable designs. the aa2020 co mes in a 24-pin plastic dip package. the aa2820 comes in a 28-pin soic package. see dimensions below. parameter symbol limits units min typ. max supply voltage vdd 4.75 5.00 5.25 v input voltage vin 3.5 - 5.00 v operating temperature ta 0 - 70 c (ambient) storage temperature ts 0 - 70 c power dissipation 250 mw supply current 50 ma min. clock pulse width twh, twl 15 usec propagation delay time tpd 3.5 5 sec (clock to output ) oscillator frequency fosc 800 1000 1200 khz rise time tr 1 usec fall time tf 1 usec
(volts) (volts) (volts) 3 4 figure 3: input/output waveform characteristics typical output characteristics figure 4: high voltage output (out5) vs. reset (r13) and out1. bilevel drive the basic function of a step motor driver is to control the motor windin g curren ts. motor performance is determined by how fast the driver ca n increase and decrease the winding currents. a rapid rise i n winding current is achieved by applying a high voltage directly to a motor. this rapid rise o f current is also referred to as the "kick" or operating current. when a desired current level is reached, a low voltage is applied to maintain a suitable holdin g current level. when a motor winding is turned off, a rapid decrease in windin g current is achieved by routing the energy in the collapsing field back to th e power supply through a high voltage path. the high vol tage supply furnishes the energy necessary to maintain mo tor output torque at high step rates thus prov iding high mechanical power output. the low voltage supply provide s much of the current needed at low step rates and all of the holding current. the eff iciency of bilevel drive makes for step motor performance that is fa r superior to that produced by l/r d rives. also, bilevel drivers do not use high frequency switching techniques as chopper drivers do. consequently, they d o not create the emi, rfi, and motor heating problems that a re associated with chopper drivers. aa2020 operation each time the chip receives a clock signal, the phase outputs change state. when a phase output turns on, a high voltage output also turns on . this high voltage output is used to turn on a high-side switch. the high voltage output will stay on until the chip gets a reset signal. in figure 4, out1 turns on whe n the clock input goes low. out5 turns on at the same time. out5 stays o n until the reset input, r13 goes low. the waveforms in figure 4 are for half - step operation. in half-step operation, the phase outputs are on for three cloc k cycles. the high voltage output will turn on the first two of these cycles. if th e reset inp ut never goes low, the high voltage output will stay on. in full-ste p operation, each phase output is on for two clock cycles and the correspondin g high voltage output will turn on at the beginning of each clock cycle.
5 6 AA2020A pin description pin name description 1 vdd power (+5vdc) 2 vdd power (+5vdc) 3 op output polarity - when this input is logic "1 ", positive true phase outputs are selected. when this input is log ic "0", negative true phase outputs are selected . only out1-out4 are affected. out5 and out 6 are always positive true. 4 out 5 high voltage output signal for phase 1 and phase 3. th is output is used to turn on a high-side switch fo r phases 1 and 3. this output goes high every tim e phase 1 or 3 turns on. this output can only be turne d off when r13 goes low. 5 in 2 ccw input (phase 2 input) - pulses applied to thi s inpu t cause the chip to sequence in th e counterclockwise direction. this input is phase 2 in when using phase inputs. 6 out 1 phase 1 output 7 out 3 phase 3 output 8 in 4 half -step/full-step (phase 4 input) - a logic "1" o n this input selects half-step operation when usin g clock inputs. a logic "0" on this inpu t select full-step operatio n. this input is phase 4 in when usin g phase inputs. 9 osc in oscillator input - see section on oscillator. 10 osc out oscillator output - see section on oscillator. 11 preset preset for power up - see section on preset 12 vss 0vdc 13 vdd power (+5vdc) 14 on/off motor on/off -a logic "1" on this input allows th e to function normally. a logic "0" on this inputs turns off all outputs. 15 out 6 high voltage signal for phase 2 and phase 4. thi s output is used to turn on a high-side switch fo r phases 2 and 4. this output goes high every tim e phase 2 or 4 turns on. this output can only be turne d off when r24 goes low. 16 r reset input for phase 1 and phase 3 high voltage - when this input goes low, out5 turns off. 17 r24 reset input for phase 2 and phase 4 high voltage - when this input goes low, out6 turns off. 18 out 4 phase 4 output 19 out 2 phase 2 output 20 in 3 dir ection/ phase 3 input - a logic "1" on this input selects clockwise direction when using clock inputs. a logic "0" on this input selects counterclockwise direction when using clock inputs. this input is phase 3 in when using phase inputs. 21 c/p clock/phase inputs - a logic "1" on this input selects clock inputs. a l ogic "0" on this input selects phase inputs. 22 ip inp ut polarity - a logic "1" on this input selects negati ve going clock inputs or negative true phase inputs. a logic "0" on this input selects positive going clock inputs or positive true phase inputs. 23 in 1 clock in/ phase 1 input - puls es applied to this input cause the chip to sequence in the clockwise directio n when using clock inputs. this input is phase 1 i n when using phase inputs. 24 vss 0vdc
+5v 49.9k 124 10k 0.1uf preset 1n4448 7 8 aa2820 pin description oscillator pin name description 1 vdd power (+5vdc) 2 hv off turns high voltage off when logic "0". this does not t h e oscillator frequency must be set at reset the high voltage outputs. 800k hz to 1.2mhz because of interna l 3 vdd power (+5vdc) timi ng. it is strongly recommended t o 4 op output polarity use the resistor and capacitor value s 5 out 5 high voltage output for phase 1 and phase 3 show n in figure 5. these values wil l 6 in 2 ccw input/ phase 2 input produce an oscillator frequency of abou t 7 out 1 phase 1 output 1 mhz. 8 out 3 phase 3 output 9 in4 half-step/full-step/ phase 4 input 10 osc in oscillator input 11 osc out oscillator output 12 preset preset for power up 13 out56 this output is a logic "1" wh en both out5 and out6 are logic "1" 14 vss 0vdc 15 vdd power (+5vdc) 16 run/stop when this input is a logic "0" all clocking is ignored 17 on/off motor on/off 18 out 6 high voltage output for phase 2 and phase 4 19 r13 reset for phase 1 and phase 3 high voltage 20 r24 reset for phase 2 and phase 4 high voltage 21 out 4 phase 4 output 22 out 2 phase 2 output the preset pin must be held a t 23 in3 direction/ phase 3 input logic "0" upon power up until th e 24 c/p clock/phase mode s upply for the chip reaches +5v. it is 25 ip input polarity recommended to use the prese t 26 in 1 clock in/ phase 1 input circuit shown in figure 6. when th e 27 clock out this output gives a pulse for each pulse on the cloc k pr eset pin is held at logic "0", al l input outputs are off (logic "0"). when th e or for each phase change when using phase inputs pr eset pin goes high, the chi p 28 vss 0vdc comes up in it's preset condition. i n inputs in bold are available only on the aa2820 soic. figure 5: oscillator r and c values. figure 6: preset circuit. half-step mode, phase 1 will be on. i n full-step mode, phase 1 and phase 2 will be on.
9 10 clock input selection the re are three three clocking methods for the AA2020A and aa2820. the c/p input is used to select clock inputs or phase inputs. the ip input i s used to select positive or negative going inputs. see table 1. input clock selection c/p ip + going clock inputs 1 0 - going clock inputs 1 1 positive true phase inputs 0 0 negative true phase inputs 0 1 table 1: clock input selection. clock and direction: pulse s applied to the clock input will cause the motor t o step in the clockwise direction if the direction input is logic "1" . pulse s applied to the clock input will cause the motor to step in th e counterc lockwise direction if the direction input is logic "0". figure 7 shows clock and direction signals which will make 5 steps in the clockwis e direction and 5 steps in the counterclockwise direction. clock and ccw: pulses applied to the clock input cause the motor t o step in the clockwise direction. pulses applied to the ccw input cause th e motor to step in the counterclockwise direction. pulses should not be applie d to both of these inputs at the same time. the input which is not being use d should be held low when using positive going clock in puts, or held high when using negative going clock inputs. figure 7 shows clock and direction signal s which will make 5 steps in the clockwise direction and 5 stepsin th e counterclockwise direction. phase inputs: half-step or full-step sequence phas e inputs may be used to syn chronize multiple axes. only the phase input sequences shown i n fi gure 8 may be used. the phase input sequences in figure 4 produc e clock wise motor movement. the phases may be reversed to obtai n coun terclockwise motor movement. positive or negative true phase input s may be used. figure 8: phase input sequence figure 7: the clock and direction signals are equivalent to the cw and ccw signals
vlv vhv +5v 2 op 3 vdd 1 c/p 21 i/p 22 in 1 23 in 2 5 in 3 20 in 4 8 on/off 14 gnd 12 gnd 24 out 3 7 out 1 6 out 5 4 vdd 13 osc in 9 osc out 10 preset 11 r13 16 r24 17 out 2 19 out 4 18 out 6 15 AA2020A +5v rsense vhv +5v +5v +5v 49.9k 0.1uf 124 10k clock ccw direction hs/fs on/off 220pf 4.22k vlv rsense vdd q1 q2 q3 q4 q5 q6 c1 c2 11 12 half-step/full-step connection diagram the a a2020a and aa2820 can operate a motor in half-step or full-ste p oper ation. in half-step mode, the motor is stepped by alternately energizing one phase, and then two phases of the motor. with a 1.8 degree moto r (200 st eps/rev), half-step mode will provide 400 steps/revolution. table 2 belo w shows the sequence for half-step. phase 1 phase 2 phase 3 phase 4 cc w cw 1 0 0 0 1 1 0 0 0 1 0 0 0 1 1 0 0 0 1 0 0 0 1 1 0 0 0 1 1 0 0 1 table 2: half-step phase sequence 1=on, 0=off in full-step mode, there are always two phases on at a time. the motor i s stepped by turning off a phase and turning on the opposite phase (i.e. - turn phase 1 off and turn phase 3 on). a standard 1.8 degree motor will provide 200 steps/ revolution in full-step mode. the phase sequence for full-step i s shown in figure y2. phase 1 phase 2 phase 3 phase 4 darlington transistors used as high-side switches. the rsense resistors are cc w cw 1 1 0 0 0 1 1 0 0 0 1 1 1 0 0 1 table 3: full-step phase sequence 1=on, 0=off figure 9: typical hookup for unipolar bilevel step motor driver using AA2020A. figur e 9 shows a typical hookup with the AA2020A chip. q1-q4 are np n darlingt on transistors used for the 4 phase outputs. q5 and q6 are pn p use d to sense the current flowing through the motor. when the current i n phase 1 or 3 reaches a level set by the potentiometer, comparator c1 goe s low (logic "0") and resets (turns off) out5. the same thing happens for phas e 2 and 4.
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