A3998SETTR-T Datasheet A3998SETTR-T | P1-P3

Description

Designed to provide the motor driver and power supply

requirements for printers and office automation equipment.

This integrated power IC incorporates two high current,

high performance, full bridge outputs, capable of 1.5 A at

50 V. Additionally two power supply rails are provided for

microprocessor or DSP supplies. A switching buck regulator

steps the supply down to a low voltage output that is adjustable

from 3.3 to 5 V. This voltage can be used to supply external 5 V

rails, it also feeds back into the part and supplies the integrated

linear regulator which is adjustable from 1 to 2.5 V.

The A3998 serial port provides flexible configuration for

the dual full bridge motor driver. Two full bridges can be

programmed to control one stepper motor or two DC motors.

Both bridges have integrated fixed off-time PWM control with

programmable decay mode selection.

The A3998 is supplied in a low profile, 32-contact QFN,

5 × 5 mm, 0.90 mm nominal height, with exposed thermal pad

(suffix ET). The package is lead (Pb) free with 100% matte-tin

leadframe plating.

A3998-DS

Features and Benefits

• 3.3/5 V switching regulator

• 1 to 2.5 V configurable linear regulator output

• Dual DMOS full bridge: drive two DC motors or

a single stepper motor

• ±1.5 A, 50 V output rating per bridge

• 4-bit microstepping capability

• Serial port control

• Configurable mixed, fast, and slow current decay

• Synchronous rectification for low power dissipation

• Internal UVLO and thermal shutdown circuitry

• Crossover-current protection

• OCP protection

Dual DMOS Full Bridge Motor Driver

With Serial Port Control and Dual Regulators

Package: 32-contact QFN (suffix ET)

Approximate size

A3998

Functional Block Diagram

Switcher PWM Control

Charge Pump

System

Control

Full Bridge

Gate Supply

SENSE1

OUT1A

OUT1B

VBB

CP1

CP2

VCP

0. 1 F

42 V

Full Bridge

Serial

Port

Controller

VBB

FB1

SW1

DATA

CLKSTB

OUT2A

OUT2B

SENSE2

ENB2

ENB1

VREF

CLK

VIN

FB2

CSN

LDO

3. 3 to 5 V

CLKGND

VBB

Monitor

PMON

FB1

SLEEPn

GND

VOUT2

VOUT1VOUT1

1 to 2. 5 V

500 m A

COUT2

10 F

VREG

GND

GD/VOUT2

VREG

To VREG

0.1 F

0.22 F

D/A

Buffer

Control

Logic

PWM Control

Full Bridge 2

PWM Control

Full Bridge 1

D/A

VBB

RST

VBB

FRST100 ms

POR

COUT1

220 F

CL2

RS1

RS2

220 F

0. 22 F

CPAD

Dual DMOS Full Bridge Motor Driver

With Serial Port Control and Dual Regulators

A3998

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Absolute Maximum Ratings*

Characteristic Symbol Notes Rating Unit

Load Supply Voltage V

50 V

Output Current I

OUT

Motor, DC 1.5 A

Pulsed, t

< 1 s6A

Sense Voltage V

SENSE

DC 0.52 V

< 1 s 2.5 V

SW1 Pin Voltage V

–1 to 50 V

Logic Pins Voltage Range V

–0.3 to 5.5 V

VIN Pin Voltage V

–0.3 to 6 V

FB Pins Voltage Range V

–0.3 to 5.5 V

VREF Pin Voltage Range V

REF

–0.3 to 5.5 V

PMON, RST Pins Voltage Range V

RST

–0.3 to 5.5 V

VREG Pin Voltage Range V

REG

–0.3 to 8 V

Operating Ambient Temperature T

S temperature range –20 to 85 ºC

Maximum Junction Temperature T

(max) 150 ºC

Storage Temperature T

stg

–55 to 150 ºC

Selection Guide

Part Number Packing*

A3998SETTR-T 1500 pieces per 7-in. reel

*Contact Allegro

™

for additional packing options

Thermal Characteristics may require derating at maximum conditions, see application information

Characteristic Symbol Test Conditions* Value Unit

Package Thermal Resistance

JA

4-layer PCB based on JEDEC standard 30 ºC/W

Estimated, on 2-layer PCB with 1 in.

of copper area each side 55 ºC/W

*Additional thermal information available on the Allegro website

Table of Contents

Specifications 2

Pin-out Diagram and Terminal List 2

Thermal Characteristics

Terminal List 3

Electrical Characteristics 4

Functional Description 7

Voltage Regulators 7

Switching Regulator 7

Linear Regulator 8

Serial Port 8

Serial Port Writing 8

Configuration Register 9

Motor Driver 9

Full Bridge Output Current Regulation 9

Fixed Off-Time 9

PWM Control Mode 9

Phase Control 10

Enable Logic 10

Fast Decay Time 10

PWM Blank Timer 10

Synchronous Rectification 10

Protection 11

Power-On Reset 11

Application Information 16

PCB Layout 16

Switcher 16

Motor Driver 16

Thermal Considerations 16

Switching Regulator Component Selection 16

Package Outline Drawing 19

Dual DMOS Full Bridge Motor Driver

With Serial Port Control and Dual Regulators

A3998

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Pin-out Diagram

Terminal List Table

Number Name Function Number Name Function

1,13,32 GND Ground 18 SW1 DC to DC switch output

2 FRST Control logic input 19 CP1 Charge pump capacitor terminal

3 SLEEPN Control logic input, active low 20 CP2 Charge pump capacitor terminal

4 CLK Control logic input 21 VCP Reservoir capacitor terminal

5 DATA Control logic input 22 NC No connect

6 STB Control logic input 23 VREG Gate supply

7 ENB1 Control logic input 24 CSN Current Sense/Reg select

8 ENB2 Control logic input 25 VIN Logic supply/ LDO supply

9 OUT2B DMOS full bridge 2, output B 26 GD/VOUT2 Gate drive output / VOUT2

10, 16 VBB Motor and switcher supply voltage 27 FB2 Feedback for VOUT2

11 OUT2A DMOS full bridge 2, output A 28 FB1 Feedback for VOUT1

12 SENSE2 Sense resistor terminal, bridge 2 29 VREF Analog input

14 SENSE1 Sense resistor terminal, bridge 1 30 RSTN Reset flag output

15 OUT1A DMOS full bridge 1, output A 31 PMON Power monitor flag output

17 OUT1B DMOS full bridge 1, output B – PAD Exposed thermal pad

PAD

GND

PMON

RSTN

VREF

FB1

FB2

GD/VOUT2

VIN

OUT2B

VBB

OUT2A

SENSE2

GND

SENSE1

OUT1A

VBB

CSN

VREG

VCP

CP2

CP1

SW1

OUT1B

GND

FRST

SLEEPN

CLK

DATA

STB

ENB1

ENB2

P1-P3 P4-P6 P7-P9 P10-P12 P13-P15 P16-P18 P19-P20

A3998SETTR-T

Mfr. #:

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IC MTR DRVR BIPOLAR 3-5.5V 32QFN

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A3998SETTR-T