SAA1027

Made by Philips Semiconductors.

(Information taken from Data Sheet dated October 1982)

Stepper Motor Drive Circuit

General Description

The SAA1027 is a bipolar integrated circuit intended for driving a four-phase two-stator motor. The circuit consists of a bidirectional four-state counter and a code converter to drive the four outputs in the sequence required for driving a stepper motor.

Features

Quick Reference Data

Supply voltage range VCC 9.5 to 18 V
Supply current, unloaded ICC typ. 4.5 mA
Input voltage, all inputs
HIGH
 VIH min. 7.5 V
LOW
 VIL max. 4.5 V
Input current, all inputs, LOW IIL typ. 30 µA
Output current LOW IOL max. 500 mA
Operating ambient temperature range Tamb -20 to +70 °C

Package outline - 16-lead DIL; plastic (SOT-38A)

Fig. 1 Block diagram. The blocks marked HNIL/CML are high noise immunity input stages, the block marked CTR2 is a bidirectional sychronous 2-bit (4-state) counter and the block marked X/Y is a code converter. C is the count input, M the mode input to select forward or reverse counting and R is the reset input which resets the counter to content zero.

Pinning

1n.c. not connected
2R reset input
3M mode input
4RX external resistor
5VEE1 ground
6Q1 output 1
7n.c. not connected
8Q2 output 2
9Q3 output 3
10n.c. not connected
11Q4 output 4
12VEE2 ground
13VCC2 positive supply
14VCC1 positive supply
15C count input
16n.c. not connected


Functional Description

Count input C (pin 15)
The outputs change state after each L to H signal trasition at the count input.

Mode input M (pin 3)
With the mode input the sequence of output signals, and hence the direction of the stepping motor, can be chosen, as shown in the following table.

Counting
sequence		 M = L M = H
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
0 L H L H L H L H
1 H L L H L H H L
2 H L H L H L H L
3 L H H L H L L H
0 L H L H L H L H

Reset input (pin 2)
A LOW level at the R input resets the counter to zero. The outputs take on the levels shown in the upper and lower line of the table above.

If this facility is not used the R input should be connected to the supply.

External resistor pin RX (pin 4)
The External resistor pin R4 connected to RX sets the base current of the output transistors. Its value has to be chosen in accordance with the required output current (see Fig. 5).

Outputs Q1 to Q4 (pins 6, 8, 9, and 11)
The circuit has open-collector outputs. To prevent damage by an overshooting output voltage the outputs are protected by diodes connected to VCC2, pin 13. High output currents mainly determine the total power dissipation, see Fig. 3.

Ratings

Limiting values in accordance with the absolute Maximum System (IEC 134)
Supply voltage, d.c. VCC1;VCC2max.18 V
Input voltage, all inputs VImax.18 V
Current into pin 4 IRXmax.120 mA
Output current IOLmax.500 mA
Power dissipation Ptotsee Fig.4
Storage temperature range Tstg-40 to +125 °C
Operating ambient temperature range Tamb-20 to +70 °C

Characteristics

VCC = 9.5 to 18 V; VEE = 0 V; Tamb= -20 to +70 °C unless otherwise specified.

parametersymbol min.typ.max.unit
Supply VCC1 and VCC2 (pins 14 and 13)
Supply Current at VCC1 = 12 V;
unloaded; all inputs HIGH; pin 4 open		 ICC24.56.5mA
Inputs C, M and R (pins 15, 3 and 2)
Input voltage:
HIGH
LOW
Input current:
HIGH
LOW		 VIH
VIL

IIH
-IIL		 7.5
-

-
-		-
-

1
30		-
4.5

-
-		V
V

µA
µA
External resistor pin RX (pin 4)
Voltage at RX at VCC = 12 V ± 15%
R4 = 130 ohm ± 5%		 VRX3-4.5V
Outputs Q1 to Q4
Output voltage LOW
at IOL = 350 mA
at IOL = 500 mA
Output current
LOW
HIGH at VQ = 18 V
VOL
VOL

IOL
-IOH		 -
-

-
-		 500
700

-
-		 1000
-

500*
50		 mV
mV

mA
µA

* See figs 3 and 4

Fig.6 Typical application of the SAA1027 as a stepping motor driver.

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Last updated 25th Nov 1997