LSI LS7561-SD, LS7561-S, LS7560-TS, LS7560-S, LS7560 Datasheet

BRUSHLESS DC MOTOR CONTROLLER

GENERAL DESCRIPTION

The LS7560/LS7561 are CMOS integrated circuits designed to
control three or four phase brushless DC motors in a closed or
open loop configuration. The IC consists of a decoder which
provides proper commutation sequencing, a frequency-to­pulse width converter and error amplifier for closed loop motor
speed control, a PWM comparator and sawtooth oscillator for
external driver power control and a 5.5V reference generator
for supplying power to motor sensors. Also included is Fault
detection and indication, overcurrent sensing, dynamic motor
braking, forward/reverse input, sensor spacing selections and
an enable input control. The overcurrent sense condition will
disable all output drivers when using the LS7560 and only the
bottom drivers when using the LS7561.

The IC operates from 10V to 18V and provides CMOS com­patible outputs for interfacing with external power devices.
Operating below 10V will activate a Fault Indication Output
and disable all Output Drivers.

INPUT/OUTPUT DESCRIPTION: (See Figure 2)
SEQUENCE SELECT Input (Pin 1 )

A High on this input selects 60°/300° and a Low selects 120°/
240° electrical sensor separation. Use of a 300° or 240° motor
will cause opposite direction rotation as compared to a 60° or
120° motor.

F/R Input (Pin 27)
A High on this input selects Forward direction and a Low se­lects Reverse direction. The motor drive outputs are disabled
for 2 clock cycles at the onset of a direction change.

July 2002

7560-030599-1

1

2

3

4

5

6

7

8

9

10

11

12

13

14 15

16

17

18

19

20

21

22

23

24

25

26

27

28

FIGURE 1. PIN CONNECTION DIAGRAM

LS7560

SEQUENCE SELECT

ENABLE

FAULT INDICATOR

RC

TACHOMETER OUT

ERROR AMP (+)

ERROR AMP (-)

OSCILLATOR

ERROR AMP OUT

CURRENT SENSE (+)

CURRENT SENSE (-)

OUT 6

OUT 5

OUT 4

OUT 3

OUT 2

OUT 1

VSS (-V)

VR

TOP DRIVER POLARITY SELECT

PWM CONTROL

BRAKE SELECT

BRAKE

S1

S2

S3

F/R

VDD (+V)

HALL
SENSORS

TOP VIEW

S1, S2, S3 Inputs (Pins 24, 25, 26)

Hall Sensor inputs which are decoded to determine the Motor
Commutation Sequence. An invalid input code disables all motor
outputs. Inputs have Schmitt Trigger buffers for noise immunity.

BRAKE Input (Pin 23)
With the BRAKE SELECT input Low, a High on the BRAKE input
forces the Top Drivers to an OFF condition and the Bottom Drivers
to a PWM ON condition. If the Motor is under Closed Loop control,
the Loop is automatically opened and the error amplifier output is
connected to the Error Amp (-) input. By controlling the voltage at
teh Error Amp (+) input, the PWM duty cycle is controlled during
braking. This manner of braking prevents the Bottom Motor Drivers
from drawing excessive current, a condition which can occur during
normal braking, when the Bottom Drivers are turned ON un­conditionally. With the BRAKE SELECT input High, a High on the
BRAKE input unconditionally causes the Top Drivers to turn OFF
and the Bottom Drivers to turn ON. The BRAKE function has prior­ity over all other functions.

BRAKE SELECT Input (Pin 22)
A Low on this input selects PWM control of braking and a High se­lects unconditional braking.

ENABLE Input (Pin 2)
When the ENABLE input is above VR/2, all Output Drivers are en­abled and when it is below VR/2.2, all Output Drivers are disabled.
This input has a nominal hysteresis of .05VR, where VR is the inter­nally generated Reference Voltage available on Pin 19. Because
the ENABLE input is level sensitive, it can easily be used to control
operation of the IC based on an Analog Fault Condition.

LSI/CSI

LSI Computer Systems, Inc. 1235 Walt Whitman Road, Melville, NY 11747 [phone] FAX [phone]

U

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A3800

FEATURES

• Open loop motor control

• Tachometer output for closed loop motor control

• Error Amplifier and PWM Speed Comparator with full accessibility

• High noise immunity Schmitt Triggers on Sensor inputs

• 5.5V Reference Supply for external sensors

• Cycle-by-cycle current sensing

• Static, or current limited dynamic, motor braking

• Output enable delay on speed direction reversal

• Enable input with fault sensing capability

• Fault Indicator output

• 60°/300° or 120°/240° electrical sensor spacing selection

• Selectable PWM of top and bottom drivers or bottom drivers only

• CMOS compatible motor outputs with drive capability

• Selectable top driver polarity

• Low power dissipation

• +10V to +18V operation (VDD-Vss)

• LS7560, LS7561 (DIP); LS7560-SD, LS7561-SD (Skinny DIP);
LS7560-S, LS7561-S (SOIC); LS7560-TS, LS7561-TS (TSSOP)
See Figure 1

LS7560
LS7561

ERROR AMPLIFIER Inputs (Pins 6, 7 ) Output (Pin 8)

For closed loop control, the TACHOMETER Output is applied
through a resistor to the negative input of the Error Amplifier on
Pin 7. A speed control potentiometer is connected to the positive
input of the Error Amplifier on Pin 6. A parallel RC Network is con­nected between the Output of the Error Amplifier on Pin 8 and Pin

7. The Amplifier, configured this way, enables the variable pulse
width to be converted to a DC voltage which is used to control the
motor speed. The potentiometer is used to set the desired motor
speed. For open loop control, configure the Error Amplifier as a
voltage follower by connecting Pin 7 directly to Pin 8 and do not
connect the TACHOMETER Output signal to the Error Amplifier.

TOP DRIVER POLARITY SELECT Input (Pin 20)
A High on this input selects a High Polarity for the Top Output
Drivers Motor ON condition and a Low selects a Low Polarity.

OUTPUT DRIVERS (Pins 12, 13, 14, 15, 16, 17)
Each Driver Output provides a CMOS compatible signal for driv­ing Buffers/Power Transistors. The Outputs are capable of sink­ing/sourcing 25mA with a 1.5V drop across the IC, at VDD = 12V.

FAULT INDICATOR Output (Pin 3)
Open drain output to provide sinking current for driving an ex­ternal device such as an LED to indicate a malfunction condition.
The output occurs under any of the following conditions:

1) Overcurrent Sense condition

2) ENABLE Input below VR/2.2

3) Invalid Sensor code

4) Chip power supply less than 9V

5) VR Output less than 4.1V

VR Output (Pin 19)

5.5V Reference Voltage Output that can supply 20mA of current
at VDD =12V for powering input Sensors.

VDD (Pin 28)
VDD is Supply Voltage positive terminal.

OSCILLATOR (Pin 9)
An external RC network is connected to this input to set the fre­quency of the Sawtooth Schmitt Trigger Oscillator. The Sawtooth
is applied to the PWM Comparator along with the output of the Er­ror Amplifier. The output of the PWM Comparator is a Pulse
Width Modulated Signal which is used to vary the effective drive
to the motor and, hence, the motor speed.

OVERCURRENT SENSE (Pins 10, 11)
The input to Pin 10 comes from the high side of a fractional ohm
current sensing resistor. The voltage at this input is compared to
an internal 100mV Reference. When the voltage exceeds the
100mV Reference, an Overcurrent Condition exists and the Out­put Drivers are switched OFF until the end of the sawtooth os­cillator ramp-up. When the sawtooth switches low, the Over­current Condition is sampled, and if it no longer exists, the Output
Drivers are switched ON again. Otherwise, the Output Drivers re­main OFF until the end of the next sawtooth. The input to Pin 11
comes from the low side (Gnd) of the current sensing resistor and
connects to the low side of the internal 100mV Reference.

PWM CONTROL Input (Pin 21)
A High on this input causes only the Bottom Drivers to be Pulse
Width Modulated. A Low on this input causes both Top and Bot­tom Drivers to have PWM.

TACHOMETER Output (Pin 5)
The output of the Frequency To Pulse Width Converter is tied to
this pin. The Converter uses the three SENSOR Inputs and ex­ternal RC Network to generate a variable frequency output with a
fixed positive pulse width.

RC Input (Pin 4)
The external RC network connected to this input programs the
positive pulse width of the Frequency to Pulse Width Converter.

VSS (Pin 18)
VSS is Supply Voltage negative terminal.

7560-040198-2

MAXIMUM RATINGS (Voltages referenced to Vss)

SYMBOL VALUE UNIT

Power Supply Voltage VDD 20 V
Voltage at any input VIN Vss - 0.3 to VR V
Operating Temperature TA -25 to +85 °C
Storage Temperature TSTG -65 to +150 °C
Output Drive Sink/Source Current Io 75 mA
VR Output Source Current IR 30 mA

ELECTRICAL CHARACTERISTICS

VDD = 12V, RT = 47kΩ, CT = 0.001µF, RS = 10kΩ, CS= 0.01µF (See Figure 3) TA = 25°C, unless otherwise specified
PARAMETER SYMBOL MIN TYP MAX UNIT

Reference Voltage VR 4.75 5.5 6.25 V
Line Regulation ∆VR - 100 200 mV
VDD = 10V to 18V, IREF =1.0mA
Temperature Stability
TA = 0°C to 70°C ∆VR - +/- 1.0 - %
TA = 0°C to 85°C ∆VR - +/- 1.3 - %

Error Amplifier:

Input Offset Voltage VIO - 5 15 mV
Input Current IIN - 0 10 nA
Input Common Mode Voltage Range VICR (0 to VR) V
Open Loop Voltage Gain (RL=15KΩ) AVOL 70 80 - dB
Common Mode Rejection Ratio CMRR 60 - - dB
Power Supply Rejection Ratio PSRR 60 - - dB

PARAMETER SYMBOL MIN TYP MAX UNIT

Output High State (RL=15kΩ to Ground) VOH VR - - V
Output Low State (RL = 15kΩ to VR) VOL - - 1.0 V
Output Source or Sink Current Io - - 1.0 mA

Oscillator:

Oscillator Frequency FOSC 21 24 27 kHz
Percentage Frequency Change per Volt ∆F OSC ∆V - 0.4 1.0 %/V

(VDD = 10V to 18V) F

Sawtooth High Voltage VOSCP - 3.8 4.5 V
Sawtooth Low Voltage VOSCV 0.7 1.0 - V
Capacitor Discharge Current ID 0.6 1.0 2.5 mA

Logic Inputs:

Input Threshold Voltage VIH 3.0 2.3 - V
(Pins 1, 20, 21, 22, 23, 24, 25, 26, 27) VIL - 1.8 1.4 V

Brake and Sensor (Pins 23, 24, 25, 26)

High State Input Current (VIN = 4V) IIH -36 -27 -20 µA
Low State Input Current (VIL = 0V) IIL -50 -40 -30 µA

Sequence Select, Top Driver Polarity
Select, PWM Control, Brake Select,
and F/R Select (Pins 1, 20, 21, 22, 27)
High State Input Current (VIN = 4V) IIH -16 -12 -8 µA
Low State Input Current (VIL = 0V) IIL -25 -17 -10 µA

ENABLE Input Threshold Voltage (Pin 2) VIH 2.1 2.8 3.2 V
Hysteresis VH 0.2 0.3 0.4 V
ENABLE Input Current IIN - - 10 nA

Overcurrent Sense Comparator:
Input Threshold Voltage VIH 85 100 115 mV
Input Current IIN - - 10 nA

Outputs:

Closed Loop Control Section:
Tachometer Out
Output High Voltage (Isource = 1.5mA) VOH VR - 0.8 VR - 0.5 VR-.3 V
Output Low Voltage (ISINK = 5mA) VOL 0.18 0.27 0.40 V
Pulse Width TW 95 105 115 µs
Capacitor Discharge Current (RC Terminal) ID 1.8 3 7.5 mA

Output Drivers (Pins 12, 13, 14, 15, 16, 17)
Sourcing 25mA VOH 9.5 10.5 11 V
Sourcing 50mA VOH 8 8.8 9.5 V
Sinking 25mA VOL 1.0 1.30 2.0 V
Sinking 50mA VOL 2.75 3.40 4.2 V
Switching Times TR 30 45 60 ns

(CL = 250pF) TF 35 50 65 ns

Switching Times TR 100 150 200 ns

(CL = 1000pF) TF 130 180 230 ns
FAULT Output Voltage (ISINK = 16mA) VFO 47 - - kΩ
FAULT Off-State Leakage IF - 10 - nA

Under Voltage Lockout:

For VDD VUV 7.0 8.5 10 V

Hysteresis VH 0.45 0.65 0.85 V
For VR VUVR 3.5 4.1 4.8 V

Hysteresis VH 0.16 0.3 0.4 V

Power Supply Current

VDD = 10V IDD - 2.0 2.5 mA

VDD = 12V IDD - 3.0 4.0 mA

VDD = 18V IDD - 7.0 11.0 mA

7560-040298-3