SGS-THOMSON L6506, L6506D Technical data

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

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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
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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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