SLA7050MLF871 - Allegro MicroSystems, Inc.

Data Sheet

28210.2

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

Combining low-power CMOS logic with high-current, high-voltage

power FET outputs, the SLA7050M translator/driver provides complete

control and drive for a two-phase unipolar stepper motor with internal

fixed off time, pulse-width modulation (PWM) control of the output

current in a power multi-chip module (PMCM™).

The CMOS logic section provides the sequencing logic, direction,

full/half-step control, synchronous/asynchronous PWM operation, and

a “sleep” function. The minimum CLOCK input is an ideal fit for

applications where a complex µP is unavailable or overburdened. TTL

or LSTTL may require the use of appropriate pull-up resistors to ensure

a proper input-logic high. For PWM current control, the maximum

output current is determined by the user’s selection of a reference

voltage and sensing resistor. The NMOS outputs are capable of sinking

up to 1 A and withstanding 46 V in the off state. Ground-clamp and

flyback diodes provide protection against inductive transients. Special

power-up sequencing is not required.

Full-step (2 phase) and half-step operation are externally selectable.

Two-phase drive energizes two adjacent phases in each detent position

(AB-BC-CD-DA). This sequence mode offers an improved torque-

speed product, greater detent torque, and is less susceptable to motor

resonance. Half-step excitation alternates between the one-phase and

two-phase modes (A-AB-B-BC-C-CD D-DA), providing an eight-step

sequence.

The SLA7050M is supplied in an 18-pin single in-line power-tab

package with leads formed for vertical mounting (suffix LF871) or

horizontal mounting (suffix LF872). The tab is at ground potential and

needs no insulation. For high-current or high-frequency applications,

external heat sinking may be required. This device is rated for continu-

ous operation between -20°C and +85°C.

FEATURES

1 A Output Rating

Internal Sequencer for Full or Half-Step Operation

PWM Constant-Current Motor Drive

Cost-Effective, Multi-Chip Solution

100 V, Avalanche-Rated NMOS

Low rDS(on) NMOS Outputs (700 mΩ typical)

Advanced, Improved Body Diodes

Half-Step and Full-Step Unipolar Drive

Inputs Compatible with 3.3 V or 5 V Control Signals

Sleep Mode

Internal Clamp Diodes

Always order by complete part number, e.g., SLA7050MLF871 .

ABSOLUTE MAXIMUM RATINGS

Driver Supply Voltage, VBB ................ 46 V

Load Supply Voltage, VM.................. 46 V

Output Current, IO.......................... 1.0 A*

Logic Supply Voltage, VDD ............... 7.0 V

Logic Input Voltage Range,

VI........................... -0.3 V to VDD+ 0.3 V

Sense Voltage, VS........................ ±2.0 V†

Reference Input Voltage Range,

VREF ................................... -0.3 V to VDD+ 0.3 V

Package Power Dissipation,

PD........................................ See Graph

Junction Temperature, TJ............. +150°C

Operating Temperature Range,

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

Storage Temperature Range,

TS............................... -30°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

junction temperature.

† Internal filtering provides protection against transients

during the first 1 µs of the current-sense pulse.

SLA7050M

Motor

Driver

Sanken Power Devices

from Allegro MicroSystems

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

Motor

Driver

Functional block diagram

Recommended operating conditions

Load Supply Voltage, VBB .................................. 10 to 44 V

Logic Supply Voltage, VDD ............................ 3.0 V to 5.5 V

Reference Input Voltage, VREF...................... 0.1 V to 1.0 V

Tab Temperature (no heat sink), TT...................... <100°C

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

www.allegromicro.com

Motor

Driver

Electrical characteristics: unless otherwise noted at TA = +25°C, VBB = 24 V, VDD = 5.0 V.

Limits

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Output drivers

Driver Supply Volt. Range VBB Operating 10 — 44 V

Drain-Source Breakdown V(BR)DS VBB = 44 V, ID = 1 mA 100 — — V

Output On Resistance rDS(on) IO = 1.0 A — 700 850 mΩ

Body Diode Forward Volt. VFIF = 1.0 A — 0.9 1.2 V

Driver Supply Current IBB —— 15 mA

VREF > 2.0 V (sleep mode) — — 1 0 0 µA

Control logic

Logic Supply Volt. Range VDD Operating 3.0 5.0 5.5 V

Logic Input Voltage VIH 0.75VDD —— V

VIL — — 0.25VDD V

Logic Input Current IIH — ±1.0 — µA

IIL — ±1.0 — µA

Max. Clock Frequency fclk 100* — — kHz

PWM Off Time toff —12 — µs

PWM Min. On Time ton(min) — 5.0 — µs

Ref. Input Voltage Range VREF Operating 0.0 — 1.5 V

Sleep mode 2.0 — — V

Ref. Input Current IREF — ±10 — µA

Sense Voltage VSTrip point — VREF —V

Propagation Delay Time tPLH Clock rising edge to output on — 2.5 — µ s

tPHL Clock rising edge to output off — 2.0 — µs

Logic Supply Current IDD — — 3.0 mA

Typical values are given for circuit design information only.

*Operation at a clock frequency greater than the specified minimum value is possible but not warranted.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

Motor

Driver

Timing chart

Logic input timing

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

www.allegromicro.com

Motor

Driver

Functional description

Device operation. The SLA7050M is a complete

stepper-motor driver with built-in translator for easy

operation with minimal control lines. It is designed to

operate unipolar stepper motors in full-step or half-step

modes. The current in each pair of outputs, all n-channel

MOSFETs, is regulated with internal fixed off-time pulse-

width modulated (PWM) control circuitry.

When a step command signal occurs on the clock input

the translator automatically sequences to the next step.

Clock (step) input. A low-to-high transition on the

clock input sequences the translator and advances the

motor one increment. The hold state is done by stopping

the CLOCK input regardless of the input level

Full/half-step select. This logic-level input sets the

translator step mode. A logic low is two-phase, full step; a

logic high is half step. Changes to this input do not take

effect until the rising edge of the clock input.

CW/CCW (direction) input. This logic-level input sets

the translator step direction. Changes to this input do not

take effect until the rising edge of the clock input.

Internal PWM current control. Each pair of outputs is

controlled by a fixed off-time PWM current-control circuit

that limits the load current to a desired value (ITRIP).

Initially, an output is enabled and current flows through

the motor winding and RS. When the voltage across the

current-sense resistor equals the reference voltage, the

current-sense comparator resets the PWM latch, which

turns off the driver for the fixed off time during which the

load inductance causes the current to recirculate for the off

time period. The driver is then re-enabled and the cycle

repeats.

Synchronous operation mode. This function pre-

vents occasional motor noise during a “hold” state, which

normally results from asynchronous PWM operation of

both motor phases. A logic high at the SYNC input is

synchronous operation; a logic low is asynchronous

operation. The use of synchronous operation during

normal stepping is not recommended because it produces

less motor torque and can cause motor vibration due to

stair-case current.

Sleep mode. Applying a voltage greater than 2 V to the

REF pin disables the outputs and puts the motor in a free

state (coast). This function is used to minimize power

consumption when not in use. It disables much of the

internal circuitry including the output MOSFETs and

regulator. When coming out of sleep mode, wait 100 µs

before issuing a step command to allow the internal

circuitry to stabilize.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

Motor

Driver

Applications information

Layout.

The printed wirting board should use a heavy ground

plane.

For optimum electrical and thermal performance, the

driver should be soldered directly into the board.

The driver supply terminal, VBB, should be decoupled

with an electrolytic capacitor placed as close to the device

as possible.

To avoid problems due to capacitive coupling of the

high dv/dt switching transients, route the high-level, output

traces away from the sensitive, low-level logic traces.

Always drive the logic inputs with a low source impedance

to increase noise immunity.

Grounding. A star ground system located close to the

driver is recommended. The logic supply return and the

driver supply return should be connected together at only a

single point — the star ground.

Logic supply voltage, VDD. Transients at this terminal

should be held to less than 0.5 V to avoid malfunctioning

operation. Both VBB and VDD may be turned on or off

separately.

Logic inputs. Unused logic inputs (CW/CCW, FULL/

HALF, or SYNC) must be connected to either ground or

the logic supply voltage.

Current sensing. To minimize inaccuracies caused by

ground-trace IR drops in sensing the output current level,

the current-sense resistor, RS, should have an independent

ground return to the star ground of the device. This path

should be as short as possible. For low-value sense

resistors, the IR drops in the printed wiring board sense

resistor’s traces can be significant and should be taken into

account. The use of sockets should be avoided as they can

introduce variation in RS due to their contact resistance.

PWM current control. The maximum value of current

limiting (ITRIP) is set by the selection of RS and the voltage

at the REF input with a transconductance function ap-

proximated by:

ITRIP = VREF/RS

The required VREF should not be less than 0.1 V. If it is,

RS should be increased for a proportionate increase in

VREF.

Typical application

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

www.allegromicro.com

Motor

Driver

Applications Information (cont’d)

Continuous Discontinuous

mode mode

Sync. signal generator

Reference voltage. In the Typical Application shown,

resistors R1 and R2 set the reference voltage as:

VREF = (VDD x R2)/(R1 + R2)

The trimming of R2 allows for the resistor tolerances

and REF input current. The sum of R1+R2 should be less

than 50 kΩ to minimize the effect of IREF.

Minimum output current. The SLA7050M uses fixed

off-time PWM current control. Due to internal logic and

switching delays, the actual load current peak will be

slightly higher than the calculated ITRIP value (especially

for low-inductance loads). These delays, plus the mini-

mum recommended VREF, limit the minimum value the

current-control circuitry can regulate. An application with

this device should maintain continuous PWM control in

order to obtain optimum torque out of the motor. The

boundary of the load current (IO(min)) between continuous

and discontinuous operation is:

IO(min) = [(VM + VSD)/Rm] x [(1/etoff/[Rm x Lm]) - 1]

where VM = load supply voltage

VF = body diode forward voltage

Rm = motor winding resistance

toff = PWM off time

Lm = motor winding inductance

To produce zero current in a motor, the REF input

should be pulled above 2 V, turning off all drivers.

Synchronous operation mode. If an external signal

is not available to control the synchronous operation

mode, a simple circuit can keep the SYNC input low while

the CLOCK input is active; the SYNC input will go high

(synchronous operation) when the CLOCK input stays low

(“hold”). The RC time constant determines the sync

trransition timing.

Temperature effects on FET outputs. Analyzing

safe, reliable operation includes a concern for the relation-

ship of NMOS on resistance to junction temperature.

Device package power calculations must include the

increase in on resistance (producing higher on voltages)

caused by increased operating junction temperatures. The

figure provides a normalized on-resistance curve, and all

thermal calculations should consider increases from the Normalized FET on resistance

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

Motor

Driver

Applications Information (cont’d)

Allowable avalanche energy Waveforms during avalanche breakdown

given +25°C limits, which may be caused by internal

heating during normal operation.

These power MOSFET outputs feature an excellent

combination of fast switching, ruggedized device design,

low on resistance, and cost effectiveness.

Avalanche energy capability. There is a surge voltage

expected when the output MOSFET turns off, and this

voltage may exceed the MOSFET breakdown voltage

(V(BR)DS). However, the MOSFETs are avalanche type

and as long as the energy (E(AV)), which is imposed on the

MOSFET by the surge voltage, is less than the maximum

allowable value, it is considered to be within its safe

operating area. Note that the maximum allowable ava-

lanche energy is reduced as a function of temperature.

In application, the avalanche energy (E(AV)) dissipated

by the MOSFET is approximated as

E(AV) = VDS(AV) x 1/2 x ID x t

Output circuit for avalanche energy

calculations

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

www.allegromicro.com

Motor

Driver

Terminal list

Terminal

Pin Name Terminal Description

1 OUTADriver output for phase A

2 N U Not usable

3 OUTA\ Driver output for phase A\

4 GATEAPhase A MOSFET Gate

5VDD Logic power supply

6 SENSEAPhase A current sense

7 CLOCK Step clock input

8 SYNC Synchronous PWM control input

9 REF Current set & “sleep” control

10 GND Supply negative return

11 CW/CCW Forward/reverse logic control input

12 FULL/HALF

Full step/half step logic control input

13 SENSEBPhase B current sense

14 VBB Driver power supply

15 GATEBPhase B MOSFET Gate

16 OUTB\ Driver output for phase B\

17 NU Not usable

18 OUTBDriver output for phase B

The products described herein are manufactured in Japan by

Sanken Electric Co., Ltd. for sale by Allegro MicroSystems, Inc.

Sanken and Allegro reserve the right to make, from time to time,

such departures from the detail specifications as may be required to

permit improvements in the performance, reliability, or

manufacturability of its products. Therefore, the user is cautioned to

verify that the information in this publication is current before placing

any order.

When using the products described herein, the applicability and

suitability of such products for the intended purpose shall be reviewed

at the users responsibility.

Although Sanken undertakes to enhance the quality and reliability of

its products, the occurrence of failure and defect of semiconductor

products at a certain rate is inevitable.

Users of Sanken products are requested to take, at their own risk,

preventative measures including safety design of the equipment or

systems against any possible injury, death, fires or damages to society

due to device failure or malfunction.

Sanken products listed in this publication are designed and intended

for use as components in general-purpose electronic equipment or

apparatus (home appliances, office equipment, telecommunication

equipment, measuring equipment, etc.). Their use in any application

requiring radiation hardness assurance (e.g., aerospace equipment) is

not supported.

When considering the use of Sanken products in applications where

higher reliability is required (transportation equipment and its control

systems or equipment, fire- or burglar-alarm systems, various safety

devices, etc.), contact a Sanken sales representative to discuss and

obtain written confirmation of your specifications.

The use of Sanken products without the written consent of Sanken in

applications where extremely high reliability is required (aerospace

equipment, nuclear power-control stations, life-support systems, etc.) is

strictly prohibited.

The information included herein is believed to be accurate and

reliable. Application and operation examples described in this

publication are given for reference only and Sanken and Allegro

assume no responsibility for any infringement of industrial property

rights, intellectual property rights, or any other rights of Sanken or

Allegro or any third party that may result from its use.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

Motor

Driver

NOTES: 1. Exact body and lead configuration at vendor’s option within limits shown.

2. Lead spacing tolerance is non-cumulative.

3. The shaded area is exposed heat spreader.

3. Recommended mounting hardware torque: 0.490 - 0.822 Nm.

4. Recommended use of metal-oxide-filled, alkyl-degenerated oil-base silicone grease: Dow Corning SC102,

Toshiba YG6260, Shin-Etsu G746, or equivalent.

SLA7050MLF871

Dimensions in inches

(for reference only)

Dimensions in millimeters

(controlling dimensions)

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

www.allegromicro.com

Motor

Driver

NOTES: 1. Exact body and lead configuration at vendor’s option within limits shown.

2. Lead spacing tolerance is non-cumulative.

3. The shaded area is exposed heat spreader.

3. Recommended mounting hardware torque: 0.490 - 0.822 Nm.

4. Recommended use of metal-oxide-filled, alkyl-degenerated oil-base silicone grease: Dow Corning SC102,

Toshiba YG6260, Shin-Etsu G746, or equivalent.

SLA7050MLF872

Dimensions in inches

(for reference only)

Dimensions in millimeters

(controlling dimensions)

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

SLA7050M

UNIPOLAR STEPPER-MOTOR

TRANSLATOR/PWM DRIVER

Motor

Driver

Packing information

20 sticks/tubes in Y direction;

3 layers of sticks/tubes in Z direction = 1080 devices per box.

18 devices per stick/tube.

A rubber stopper is provided at each end of the stick/tube.