2919
DUAL FULL-BRIDGE
MOTOR DRIVER

DUAL FULL-BRIDGE

PWM MOTOR DRIVER

A2919SB

PWM 2

PWM 1

GROUND

PHASE

REF 2

REF 1

PHASE

OUT

SENSE

OUT

SENSE

OUT

LOAD
SUPPLY

LOGIC
SUPPLY

Dwg. PP-005

Data Sheet

29319.21

ABSOLUTE MAXIMUM RATINGS

at T

150

Motor Supply Voltage, V

................... 45 V

Output Current, I

OUT

(Peak, t

s) ........................

1.0 A

(Continuous) ..........................

750 mA

Logic Supply Voltage, V

................... 7.0 V

Logic Input Voltage Range,

............................... -0.3 V to +7.0 V

Output Emitter Voltage, V

.................. 1.5 V

Package Power Dissipation,

....................................... See Graph

Operating Temperature Range,

................................. -20

C to +85

Storage Temperature Range,

............................... -55

C to +150

Output current rating may be limited by duty cycle,
ambient temperature, and heat sinking. Under any
set of conditions, do not exceed the specified peak
current rating or a junction temperature of +150

The A2919SB and A2919SLB motor drivers are designed to drive

both windings of a bipolar stepper motor or bidirectionally control two
dc motors. Both bridges are capable of sustaining 45 V and include
internal pulse-width modulation (PWM) control of the output current to
750 mA. The outputs have been optimized for a low output-saturation
voltage drop (less than 1.8 V total source plus sink at 500 mA).

For PWM current control, the maximum output current is deter-

mined by the user's selection of a reference voltage and sensing
resistor. Two logic-level inputs select output current limits of 0%, 41%,
67%, or 100% of the maximum level. A PHASE input to each bridge
determines load current direction.

The bridges include both ground clamp and flyback diodes for

protection against inductive transients. Internally generated delays
prevent cross-over currents when switching current direction. Special
power-up sequencing is not required. Thermal protection circuitry
disables the outputs if the chip temperature exceeds safe operating
limits.

The A2919SB is supplied in a 24-pin dual in-line plastic batwing

package with a copper lead-frame and heat sinkable tabs for improved
power dissipation capabilities. The A2919SLB is supplied in a 24-lead
surface-mountable SOIC. Their batwing construction provides for
maximum package power dissipation in the smallest possible construc-
tion. The A2919SB/SLB are available for operation from -40

C to

+85

C. To order, change the suffix from 'S' to 'E'. These devices

are also available on special order for operation to +125

C. For

applications not requiring quarter-step operation, but desire lower
detent or running current, the similar UDN2916B/EB/LB may be pre-
ferred.

FEATURES

750 mA Continuous Output Current

45 V Output Sustaining Voltage

Internal Clamp Diodes

Internal PWM Current Control

Low Output Saturation Voltage

Internal Thermal Shutdown Circuitry

Half- or Quarter-Step Operation of Bipolar Stepper Motors

Always order by complete part number:

Part Number

Package

A2919SB

24-Pin DIP

C/W

6.0

C/W

A2919SLB

24-Lead SOIC

C/W

6.0

C/W

2919

2919
DUAL FULL-BRIDGE
MOTOR DRIVER

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

A2919SLB

PWM CURRENT-CONTROL CIRCUITRY

GROUND

PHASE

REF 2

REF 1

PHASE

OUT

SENSE

OUT

SENSE

OUT

LOAD SUPPLY

LOGIC SUPPLY

PWM 2

PWM 1

Dwg. PP-047

100

125

150

ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS

TEMPERATURE IN

Dwg. GP-049A

R = 6.0

C/W

SUFFIX 'B', R = 40

C/W

SUFFIX 'LB', R = 55

C/W

TRUTH TABLE

PHASE

OUT

REF

Dwg. EP-007-3

SENSE

ONE

SHOT

SOURCE
DISABLE

OUT A

OUTB

'B' PACKAGE,
CHANNEL 1
PIN NUMBERS
SHOWN.

60 k

120 k

42 k

W
Copyright © 1994 Allegro MicroSystems, Inc.

2919
DUAL FULL-BRIDGE
MOTOR DRIVER

ELECTRICAL CHARACTERISTICS at T

= +25

C, T

150

C, V

= 45 V, V

= 4.75 V to 5.25 V,

REF

= 5.0 V (unless otherwise noted).

(at trip point)

Limits

Characteristic

Symbol

Test Conditions

Min.

Typ.

Max.

Units

Output Drivers (OUT

or OUT

)

Motor Supply Range

Operating

Output Leakage Current

CEX

OUT

= V

< 1.0

OUT

= 0

<-1.0

-50

Output Sustaining Voltage

CE(sus)

OUT

750 mA, L = 3.0 mH

45 + V

Output Saturation Voltage

CE(SAT)

Sink Driver, I

OUT

= +500 mA

0.4

0.6

Sink Driver, I

OUT

= +750 mA

1.0

1.2

Source Driver, I

OUT

= -500 mA

1.0

1.2

Source Driver, I

OUT

= -750 mA

1.3

1.5

Clamp Diode Leakage Current

45 V

< 1.0

Clamp Diode Forward Voltage

= 750 mA

1.6

2.0

Driver Supply Current

BB(ON)

Both Bridges ON, No Load

BB(OFF)

Both Bridges OFF

5.0

Control Logic

Input Voltage

IN(1)

All inputs

2.4

IN(0)

All inputs

0.8

Input Current

IN(1)

= 2.4 V

<1.0

= 0.8 V

- 3.0

-200

Reference Voltage Range

REF

1.0

7.5

Current Limit Threshold

REF

/ V

SENSE

= I

= 0.8 V, V

REF

= 1.0 V to 7.5 V

9.5

10.5

= 2.4 V, I

= 0.8 V,

13.5

16.5

REF

= 1.5 V to 7.5 V

= 0.8 V, I

= 2.4 V,

20.7

24.4

28.0

REF

= 1.5 V to 7.5 V

Thermal Shutdown Temperature

170

Total Logic Supply Current

CC(ON)

= I

= 0.8 V, No Load

CC(OFF)

= I

= 2.4 V, No Load

Total Reference Current

REF1

+ I

REF2

REF1

= V

REF2

= 7.5 V, I

= I

= 2.4 V

140

185

250

2919
DUAL FULL-BRIDGE
MOTOR DRIVER

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000

APPLICATIONS INFORMATION

PWM CURRENT CONTROL

The A2919SB/SLB dual bridges are

designed to drive both windings of a bipolar
stepper motor. Output current is sensed and
controlled independently in each bridge by
an external sense resistor (R

), internal

comparator, and monostable multivibrator.

When the bridge is turned ON, current

increases in the motor winding and flows
through the external sense resistor until the
sense voltage (V

) reaches the level set at

the comparator's input:

TRIP

= V

REF

/10 R

The comparator then triggers the

monostable, which turns OFF the source
driver of the bridge. The actual load current
peak will be slightly higher than the trip point
(especially for low-inductance loads) be-
cause of the internal logic and switching
delays. This delay (t

) is typically 2

s. After

turn-off, the motor current decays, circulating
through the ground-clamp diode and sink
transistor. The source driver's OFF time
(and therefore the magnitude of the current
decrease) is determined by the monostable's
external RC timing components, where
t

off

= R

within the range of 20 k

100 k

and 100 pF to 1000 pF.

When the source driver is re-enabled,

the winding current (the sense voltage) is
again allowed to rise to the comparator's
threshold. This cycle repeats itself, maintain-
ing the average motor winding current at the
desired level.

Loads with high distributed capacitances

may cause current spikes capable of tripping
the comparator, resulting in erroneous
current control. An external R

time delay

should be used to delay the action of the
comparator. Depending on load type, many
applications will not require these external
components (SENSE connected to E).

PWM OUTPUT CURRENT WAVE FORM

LOAD CURRENT PATHS

Dwg. WM-003-1A

PHASE

OUT

off

TRIP

Dwg. EP-006-1

R S

BRIDGE ON
SOURCE OFF
ALL OFF

2919
DUAL FULL-BRIDGE
MOTOR DRIVER

LOGIC CONTROL OF OUTPUT CURRENT

Two logic level inputs (l

and I

) allow digital selection

of the motor winding current at 100%, 67%, 41%, or 0% of
the maximum level per the table. The 0% output current
condition turns OFF all drivers in the bridge and can be
used as an OUTPUT ENABLE function.

CURRENT-CONTROL TRUTH TABLE

Output Current

REF

/10 R

= 100% I

TRIP

REF

/15 R

= 67% I

TRIP

REF

/24.4 R

= 41% I

TRIP

These logic level inputs greatly enhance the implem-

entation of

P-controlled drive formats.

During half-step operations, l

and l

allow the

P to

control the motor at a constant torque between all posi-
tions in an eight-step sequence. This is accomplished by
digitally selecting 100% drive current when only one phase
is ON and 67% drive current when two phases are ON.
Logic highs on both l

and l

turn OFF all drivers to allow

rapid current decay.

During quarter-step operation, I

and I

allow the

P to

control the motor position in a sixteen-step sequence.
This is accomplished by digitally selecting drive current as
shown in the table (for one quadrant of operation). Logic
highs on both I

and I

turn OFF all drivers to allow rapid

current decay.

The logic control inputs can also be used to select a

reduced current level (and reduced power dissipation) for
`hold' conditions and/or increased current (and available
torque) for start-up conditions.

QUARTER-STEPPING CURRENT CONTROL

Phase 1

Phase 2

Current Level

100%

41%

67%

41%

100%

GENERAL

The PHASE input to each bridge determines the

direction motor winding current flows. An internally
generated deadtime (approximately 2

s) prevents cross-

over currents that can occur when switching the PHASE
input.

All four drivers in the bridge output can be turned OFF

between steps (l

= l

2.4 V) resulting in a fast current

decay through the internal output clamp and flyback
diodes. The fast current decay is desirable in half-step and
high-speed applications. The PHASE, l

, and I

inputs

float high.

Varying the reference voltage (V

REF

) provides continu-

ous control of the peak load current for micro-stepping
applications.

Thermal protection circuitry turns OFF all drivers when

the junction temperature reaches +170

C. It is only

intended to protect the device from failures due to exces-
sive junction temperature and should not imply that output
short circuits are permitted. The output drivers are re-
enabled when the junction temperature cools to +145

The A2919SB/SLB output drivers are optimized for

low output saturation voltages--less than 1.8 V total
(source plus sink) at 500 mA. Under normal operating
conditions, when combined with the excellent thermal
properties of the batwing package design, this allows
continuous operation of both bridges simultaneously at
500 mA.

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