L6506
L6506
L6506D
CURRENT CONTROLLER FOR STEPPING MOTORS
DESCRIPTION
The L6506/D is a linear integrated circuit designed to sense and control the current in stepping motors and similar devices. When used in conjunctionwith the L293, L298, L7150, L6114/L6115, the chip set forms a constant current drive for an inductive load and performs all the interfacefunctionfrom the control logic thru the power stage.
Two or more devices may be synchronized using the sync pin. In this mode of operation the oscillator in themaster chip sets the operatingfrequencyin all chips.
DIP18 |
SO 20 |
ORDERING NUMBERS: |
|
L6506 |
L6506D |
BLOCK DIAGRAM (pin's number referred to DIP-18)
June 1997 |
1/8 |
L6506 -L6506D
PIN CONNECTIONS (top view)
DIP 18 |
SO20 |
ABSOLUTE MAXIMUM RATINGS
Symb ol |
Parameter |
Value |
Un it |
VCC |
Supply Voltage |
10 |
V |
Vi |
Input Signals |
7 |
V |
Ptot |
Total Power Dissipation (Tamb = 70°C) for DIP18 |
1 |
W |
|
Total Power Dissipation (Tamb =70ÉC) for SO20 |
0.8 |
W |
Tj |
Junction Temperature |
150 |
°C |
Tstg |
Storage Temperature |
-40 to 150 |
°C |
THERMAL DATA |
|
|
Symbol |
Parameter |
|
DIP18 |
SO20 |
Unit |
Rth j-amb |
Thermal Resistance Junction-ambient |
Max. |
80 |
100 |
°C/W |
ELECTRICAL CHARACTERESTICS (VCC = 5.0V, Tamb = 25°C; unless otherwise noted)
Symbol |
Parameter |
T est Co ndi tio ns |
Min. T yp. Max. Un it |
||
VCC |
Supply Voltage |
|
4.5 |
7 |
V |
ICC |
Quiescent Supply Current |
VCC = 7V |
|
25 |
mA |
COMPARATOR SECTION
Symbol |
Parameter |
T est Co ndi tio ns |
Min. T yp. Max. |
Un it |
|
VIN |
Input Voltage Range |
Vsense Inputs |
±0.3 |
3 |
V |
VIO |
Input Offset Voltage |
VIN = 1.4V |
|
±5.0 |
mV |
IIO |
Input Offset Current |
|
|
±200 |
nA |
IIB |
Input Bias Current |
|
|
1 |
μA |
|
Response time |
VREF = 1.4V VSENS = 0 to 5V |
0.8 |
1.5 |
μs |
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L6506 - L6506D
ELECTRICAL CHARACTERISTICS (continued)
COMPARATOR SECTION PERFORMANCE (Over Operating Temperature Range)
Symbol |
Parameter |
Test Condtions |
Min. |
Typ. |
Max. |
Unit |
VIO |
Input Offset Voltage |
VIN = 1.4V |
|
|
±20 |
mV |
IIO |
Input Offset Curent |
|
|
|
±500 |
nA |
LOGIC SECTION (Over Operating Temperature Range - TTL compatible inputs & outputs)
Symbol |
Parameter |
Test Condtions |
Min. |
Typ. |
Max. |
Unit |
VIH |
Input High Voltage |
|
2 |
|
Vs |
V |
VIL |
Input Low Voltage |
|
|
|
0.8 |
V |
VOH |
Output High Voltage |
VCC = 4.75V |
2 |
3.5 |
|
V |
|
|
IOH = 400μA |
|
|
|
|
VOL |
Ouptut Low Voltage |
VCC = 4.75V |
|
0.25 |
0.4 |
V |
|
|
IOH = 4mA |
|
|
|
|
IOH |
Ouput Source Current - Outputs |
VCC = 4.75V |
2.75 |
|
|
mA |
|
1 - 4 |
|
|
|
|
|
OSCILLATOR
Symbol |
Parameter |
Test Condtions |
Min. |
Typ. |
Max. |
Unit |
fosc |
Frequency Range |
|
5 |
|
70 |
KHz |
VthL |
Lower Threshold Voltage |
|
|
0.33 VCC |
|
V |
VthH |
Higher Threshold Voltage |
|
|
0.66 VCC |
|
V |
Ri |
Internal Discharge Resistor |
|
0.7 |
1 |
1.3 |
kΩ |
CIRCUIT OPERATION
The L6506 is intended for use with dual bridge drivers, such as the L298, quad darlington arrays, such as the L7150, quad DMOS array such as L6114L6115,or discretepower transistorsto drive stepper motorsand other similar loads.The main functionof thedevice is to senseand control the currentin each of the load windings.
A commonon-chiposcillatordrives thedualchopper and sets the operatingfrequencyfor the pulse width modulated drive. The RC network on pin 1 sets the operating frequency which is given by the equation
:
f = |
1 |
for R > 10 K |
0.69 RC |
The oscillator provides pulses to set the two flipflops which in turn cause the outputs to activate the drive. When the current in the load winding reaches the programmed peak value, the voltage across the sense resistor (Rsense) is equal to Vref and the corresponding comparator resets its flip-flop interrupting the drive current untilthe next oscillatorpulse occurs. The peak current in each winding is programmed by selecting the value of the sense resis-
tor and Vref. Since separate inputs are provided for each chopper, each of the loads may be programmed independently allowing the device to be used to implement microstepping of the motor. Lowerthreshold of L6506'soscillator is 1/3VCC. Upper threshold is 2/3 VCC and internal discharge resistor is 1 KΩ ± 30 %.
Ground noise problems in multiple configurations can be avoided by synchronizing the oscillators. This may be done by connecting the sync pins of each of the devices with the oscillator output of the master deviceand connectingthe R/C pin of the unused oscillators to ground.
The equations for the active time of the sync pulse (T2), the inactivetimeof thesync signal(T1)and the dutycycle canbe foundby lookingat thefigure1 and are :
R1 RIN |
|
T2 = 0.69 C1 R1 + RIN |
(1) |
T1 = 0.69 R1 C1 |
(2) |
T2 |
|
DC = T1 + T2 |
(3) |
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