DRV8461SPWPR datasheet(15/117 Pages) TI

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7 Detailed Description

7.1 Overview

The DRV8461 is an integrated motor-driver solution for bipolar stepper motors. The device integrates two

N-channel power MOSFET H-bridges, current sense resistors, current regulation circuitry, and a microstepping

indexer. The DRV8461 is capable of supporting wide supply voltage of 4.5 V to 65 V. The device is available

in two packages - a 44-pin HTSSOP (DDW) package; and another 28-pin HTSSOP (PWP) package. The

DRV8461 provides an output current up to 4.8-A peak, 3-A full-scale, or 2.1-A root mean square (rms). The

actual full-scale and rms current depends on the ambient temperature, supply voltage, and PCB thermal design.

To provide scalable voltage and current solutions for the system design, the DRV8461 DDW package is pin-to-

pin compatible with the DRV8462 and DRV8452, and the PWP package is pin-to-pin compatible with DRV8424,

DRV8426, DRV8452 and DRV8434.

The DRV8461 integrates the auto-torque feature to reduce power loss and improve system efficiency by

adjusting output current according to the load torque. The SPI interface provides various options to optimize

the performance of the auto-torque algorithm for specific motor and system use case. The stall detection feature

detects and reports a motor stall condition to the system controller when the motor is obstructed or has reached

an end-of-travel stop. Additionally, the standstill power saving mode reduces power loss when the motor is at

holding position.

The DRV8461 uses an integrated current-sense architecture which eliminates the need for two external power

sense resistors, hence saving significant board space, BOM cost, design efforts and reduces significant power

consumption. This architecture eliminates the power dissipated in the sense resistors by using a current mirror

approach and using the internal power MOSFETs for current sensing. Optional external power sense resistors

can also be connected between the PGND pins and board ground to monitor motor health and for implementing

closed-loop algorithms such as Field Oriented Control. The current regulation set point is adjusted by the voltage

at the VREF pin. For the SPI interface, an 8-bit register allows the controller to scale the output current without

needing to scale the VREF voltage reference; and another 8-bit register allows configuration of the holding

current level for the purpose of reducing power loss at motor standstill.

A STEP/DIR pin interface allows an external controller to manage the direction and step rate of the stepper

motor. The internal microstepping indexer can execute high-accuracy micro-stepping without requiring the

external controller to manage the winding current level. The indexer is capable of full step, half step, and 1/4,1/8,

1/16, 1/32, 1/64, 1/128, and 1/256 microstepping. High microstepping contributes to significant audible noise

reduction and smooth motion. The automatic microstepping mode interpolates the input step frequency to high

resolution, thereby improving current regulation and reducing audible noise while running with a low frequency

step input from the controller. The custom microstepping table allows adjusting the current waveform to the

needs of a particular motor.

Stepper motor drivers need to re-circulate the winding current by implementing several types of decay modes,

such as slow decay, mixed decay and fast decay. The DRV8461 supports smart tune decay modes. The smart

tune is an innovative decay mechanism that automatically adjusts for optimal current regulation performance

agnostic of supply voltage and motor speed variations and aging effects. Smart tune Ripple Control uses a

variable off-time ripple current control scheme to minimize distortion of the motor winding current. Smart tune

Dynamic Decay uses a fixed off-time dynamic fast decay percentage scheme. Along with the smart tune decay

modes, the DRV8461 also features a silent step decay mode for noiseless operation at standstill and low speeds

of rotation.

The device integrates a spread spectrum clocking feature for both the internal digital oscillator and internal

charge pump. This feature minimizes the electromagnetic emissions from the device. A low-power sleep mode is

included which allows the system to save power when not actively driving the motor.

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DRV8461

SLOSE98 – DECEMBER 2022

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DRV8461SPWPR Datasheet(PDF) 15 Page - Texas Instruments

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