3962
DUAL FULL-BRIDGE
PWM MOTOR DRIVER

DISCONTINUED PRODUCT

FOR REFERENCE ONL

-- See A3964SLB

DUAL FULL-BRIDGE PWM MOTOR DRIVER

Always order by complete part number: A3962SLB .

ABSOLUTE MAXIMUM RATINGS

Load Supply Voltage, V

. . . . . . . . . 30 V

Output Current, I

OUT

. . . . . . . . . .

800 mA*

Logic Supply Voltage, V

. . . . . . . . . 7.0 V

Logic Input Voltage Range,

. . . . . . . . . . . -0.3 V to V

+ 0.3 V

Sense Voltage, V

SENSE

. . . . . . . . . . . . 1.0 V

Reference Output Current,

REF OUT

. . . . . . . . . . . . . . . . . . . 1.0 mA

Package Power Dissipation,

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

Operating Temperature Range,

. . . . . . . . . . . . . . . . -20°C to +85°C

Junction Temperature, T

. . . . . . . +150°C

Storage Temperature Range,

. . . . . . . . . . . . . . . -55°C to +150°C

* Output current rating may be limited by duty

cycle, ambient temperature, and heat sinking.
Under any set of conditions, do not exceed the
specified current rating or a junction tempera
ture of 150°C.

Fault conditions that produce excessive junction

temperature will activate the device's thermal
shutdown circuitry. These conditions can be
tolerated but should be avoided.

Data Sheet

29319.27

Designed for pulse-width modulated (PWM) current control of

bipolar stepper motors, the A3962SLB is capable of continuous output
currents to

800 mA and operating voltages to 30 V. Internal fixed

off-time PWM current-control circuitry can be used to regulate the
maximum load current to a desired value. An internal precision voltage
reference is provided to improve motor peak-current control accuracy.
The peak load current limit is set by the user's selection of an external
resistor divider and current-sensing resistors.

The fixed off-time pulse duration is set by user-selected external

RC timing networks. The capacitor in the RC timing network also
determines a user-selectable blanking window that prevents false
triggering of the PWM current control circuitry during switching transi-
tions. This eliminates the need for two external RC filter networks on
the current-sensing comparator inputs.

For each bridge the PHASE input controls load current polarity by

selecting the appropriate source and sink driver pair. For each bridge
the ENABLE input, when held high, disables the output drivers. Spe-
cial power-up sequencing is not required. Internal circuit protection
includes thermal shutdown with hysteresis, transient-suppression
diodes, and crossover-current protection.

The A3962SLB is supplied in a 20-lead plastic SOIC with copper

heat sink tabs. The power tab is at ground potential and needs no
electrical isolation.

FEATURES

800 mA Continuous Output Current Rating

30 V Output Voltage Rating

Internal PWM Current Control, Saturated Sink Drivers

Internally Generated Precision 2.5 V Reference

Internal Transient-Suppression Diodes

Internal Thermal-Shutdown Circuitry

Crossover-Current Protection, UVLO Protection

Automotive Capable

3962

PWM 1

PWM 2

GROUND

PHASE

REF(OUT)

REF(IN)

PHASE

OUT

SENSE

OUT

SENSE

OUT

LOAD

SUPPLY

LOGIC
SUPPLY

Dwg. PP-047-1

ENABLE

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

3962
DUAL FULL-BRIDGE
PWM MOTOR DRIVER

FUNCTIONAL BLOCK DIAGRAM AND TYPICAL

BIPOLAR STEPPER MOTOR APPLICATION

TRUTH TABLE

ENABLE

PHASE

OUT

Off

X = Irrelevant

100

125

150

2.5

1.5

1.0

0.5

TEMPERATURE in

2.0

R = 6

C/W

R = 60

C/W

ALLOWABLE PACKAGE POWER DISSIPATION in WATTS

Dwg. GP-019-1

MOTOR SUPPLY

OUT

ENABLE 1

PHASE 1

CONTROL LOGIC
AND LEVEL SHIFT

OUT

ENABLE 2

PHASE 2

OUT

SENSE

GND

REF

OUT

REF

SENSE

BLANKING

TIME AND

SOURCE

DRIVER T

CONTROL

OFF

UVLO

AND

TSD

CONTROL LOGIC
AND LEVEL SHIFT

BLANKING

TIME AND

SOURCE

DRIVER T

CONTROL

OFF

VOLTAGE

REFERENCE

LOGIC SUPPLY

3962
DUAL FULL-BRIDGE
PWM MOTOR DRIVER

Load Supply Voltage Range

Operating, I

OUT

800 mA, L = 3 mH

5.0

Output Sustaining Voltage

CE(sus)

OUT

800 mA, L = 3 mH

30 +V

Output Leakage Current

CEX

OUT

= V

<1.0

OUT

= 0 V

<1.0

-50

Output Saturation Voltage

CE(SAT)

Source Driver, I

OUT

= -500 mA

1.0

1.2

Source Driver, I

OUT

= -750 mA

1.1

1.5

Source Driver, I

OUT

= -800 mA

1.7

Sink Driver, I

OUT

= +500 mA

0.3

0.6

Sink Driver, I

OUT

= +750 mA

0.5

1.2

Sink Driver, I

OUT

= +800 mA

1.5

Clamp Diode Forward Voltage

= 500 mA

1.1

1.4

(Sink or Source)

= 750 mA

1.3

1.6

= 800 mA

1.7

Motor Supply Current

BB(ON)

ENABLE

= 0.8 V

5.0

7.0

(No Load)

BB(OFF)

ENABLE

= 2.4 V

5.0

7.0

ELECTRICAL CHARACTERISTICS at T

= +25

C, V

= 30 V, V

= 4.75 V to 5.25 V, V

SENSE

= 0

V, 30 k

& 1000 pF RC to Ground (unless noted otherwise)

Limits

Characteristic

Symbol

Test Conditions

Min.

Typ.

Max.

Units

Output Drivers

Continued next page...

Logic Supply Voltage Range

Operating

4.75

5.25

Logic Input Voltage

IN(1)

2.4

IN(0)

0.8

Logic Input Current

IN(1)

= 2.4 V

<1.0

IN(0)

= 0.8 V

<-2.0

-200

Control Logic

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

3962
DUAL FULL-BRIDGE
PWM MOTOR DRIVER

Reference Output Voltage

REF OUT

= 5.0 V, I

REF OUT

= 90 to 900

2.45

2.50

2.55

Reference Output Current

REF OUT

3 k

= R

+ R

15 k

150

900

Ref. Input Offset Current

REF IN

= 1 V

-2.5

1.0

Comparator Input Offset Volt.

REF

= 0 V

-6.0

6.0

Comparator Input Volt. Range

REF

Operating

-0.3

1.0

PWM RC Fixed Off-time

OFF RC

= 1000 pF, R

= 30 k

PWM Propagation Delay Time

PWM

Comparator Trip to Source OFF

1.2

2.0

PWM Minimum On Time

ON (min)

= 1000 pF

5%, R

15 k

, V

= 5 V

2.5

3.6

Propagation Delay Times

OUT

800 mA, 50% to 90%:

ENABLE ON to Source ON

3.2

ENABLE OFF to Source OFF

1.2

ENABLE ON to Sink ON

3.2

ENABLE OFF to Sink OFF

0.7

PHASE Change to Sink ON

3.2

PHASE Change to Source ON

3.2

PHASE Change to Sink OFF

0.7

PHASE Change to Source OFF

1.2

Thermal Shutdown Temp.

165

Thermal Shutdown Hysteresis

UVLO Disable Threshold

2.5

2.7

2.9

UVLO Hysteresis

0.7

0.9

1.1

Logic Supply Current

CC(ON)

ENABLE1

= V

ENABLE2

= 0.8 V

CC(OFF)

ENABLE1

= V

ENABLE2

= 2.4 V

Logic Supply Current

CC(ON)

ENABLE 1

ENABLE 2

= 0.8 V

0.18

mA/

Temperature Coefficient

Limits

Characteristic

Symbol

Test Conditions

Min.

Typ.

Max.

Units

ELECTRICAL CHARACTERISTICS at T

= +25

C, V

= 30 V, V

= 4.75 V to 5.25 V, V

SENSE

= 0

V, 30 k

& 1000 pF RC to Ground (unless noted otherwise) (cont.)

Control Logic (Continued)

NOTES: 1. Typical Data is for design information only.

2. Negative current is defined as coming out of (sourcing) the specified device terminal.

3962
DUAL FULL-BRIDGE
PWM MOTOR DRIVER

FUNCTIONAL DESCRIPTION

Internal PWM Current Control. The A3962SLB contains
a fixed off-time pulse-width modulated (PWM) current-
control circuit that can be used to limit the load current to
a desired value. The peak value of the current limiting
(I

TRIP

) is set by the selection of an external current-sensing

resistor (R

) and reference input voltage (V

REF IN

). The

internal circuitry compares the voltage across the external
sense resistor to the voltage on the reference input
terminal (V

REF IN

) resulting in a transconductance function

approximated by:

The reference input voltage is typically set with a

resistor divider from V

REF OUT

. To ensure proper operation

of the voltage reference, the resistor divider (R

= R

)

should have an impedance of 3 k

to 15 k

. Within this

range, a low impedance will minimize the effect of the REF
IN input offset current.

The current-control circuitry limits the load current

as follows: when the load current reaches I

TRIP

, the

comparator resets a latch that turns off the selected source
driver. The load inductance causes the current to recircu-
late through the sink driver and flyback diode.

For each bridge, the user selects an external resistor

) and capacitor (C

) to determine the time period

OFF

= R

) during which the source driver remains

disabled (see "RC Fixed Off-time" below). The range of
recommended values for C

and R

are 1000 pF to

1500 pF and 15 k

to 100 k

respectively. For optimal

load current regulation, C

is normally set to 1000 pF

(see "Load Current Regulation" below). At the end of the
RC interval, the source driver is enabled allowing the load
current to increase again. The PWM cycle repeats,
maintaining the peak load current at the desired value.

RC Blanking. In addition to determining the fixed off-time
of the PWM control circuit, the C

component sets the

comparator blanking time. This function blanks the output
of the comparator when the outputs are switched by the

internal current-control circuitry (or by the PHASE or
ENABLE inputs). The comparator output is blanked to
prevent false over-current detections due to reverse-
recovery currents of the clamp diodes, and/or switching
transients related to distributed capacitance in the load.

During internal PWM operation, at the end of the t

OFF

time, the comparator's output is blanked and C

begins to

be charged from approximately 1.1 volts by an internal
current source of approximately 1 mA. The comparator
output remains blanked until the voltage on C

reaches

approximately 3.0 volts.

When a transition of the PHASE input occurs, C

is discharged to near ground during the crossover delay
time (the crossover delay time is present to prevent
simultaneous conduction of the source and sink drivers).
After the crossover delay, C

is charged by an internal

current source of approximately 1 mA. The comparator
output remains blanked until the voltage on C

reaches

approximately 3.0 volts.

When the device is disabled, via the ENABLE input,

is discharged to near ground. When the device is

re-enabled, C

is charged by an internal current source of

approximately 1 mA. The comparator output remains
blanked until the voltage on C

reaches approximately

3.0 volts.

The minimum recommended value for C

1000 pF. This value ensures that the blanking time is
sufficient to avoid false trips of the comparator under
normal operating conditions. For optimal regulation of the
load current, the above value for C

is recommended and

the value of R

can be sized to determine t

OFF

. For more

information regarding load current regulation, see below.

Load Current Regulation. Because the device operates
in a slow decay mode (2-quadrant PWM mode), there is
a limit to the lowest level that the PWM current control
circuitry can regulate load current. The limitation is due
to the minimum PWM duty cycle, which is a function of the
user-selected value of t

OFF

and the minimum on-time pulse

ON(min)

max that occurs each time the PWM latch is reset.

If the motor is not rotating, as in the case of a stepper
motor in hold/detent mode, a brush dc motor when stalled
or at startup, the worst case value of current regulation can
be approximated by:

REF IN

TRIP

[(V

- V

SAT(SOURCE+SINK)

) t

ON(min)

max] (1.05 (V

SAT(SINK)

+ V

) t

OFF

)

1.05 (t

ON(min)

max + t

OFF

) R

LOAD

AVG

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