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9.2 Typical Applications

9.2.1 Three-Phase Brushless-DC Motor Control

In this application, the DRV8317 is used to drive a brushless-DC motor using PWMs from an external

microcontroller.

9.2.1.1 Detailed Design Procedure

Table 9-1 lists the example input parameters for the system design.

Table 9-1. Design Parameters

DESIGN PARAMETERS

REFERENCE

EXAMPLE VALUE

Supply voltage

VVM

12 V

Motor RMS current

IRMS

2 A

Motor peak current

IPEAK

3 A

PWM Frequency

fPWM

50 kHz

Slew Rate Setting

200 V/µs

VIN_AVDD supply voltage

VVIN_AVDD

12 V

CSA reference voltage

VCSA_REF

3.0 V

System ambient temperature

–20°C to +50°C

9.2.1.1.1 Motor Voltage

Brushless-DC motors are typically rated for a certain voltage (for example, 5V or 12V). The DRV8317 allows for

a range of possible operating voltages from 4.5-V to 20-V.

9.2.1.2 Driver Propagation Delay and Dead Time

The propagation delay is defined as the time taken for changing input logic edges INHx and INLx (whichever

changes first, if MCU dead time is added) to change the half-bridge output voltage (OUTx). Driver propagation

delay (tPD) and dead time (tdead) are specified with a typical and maximum value, but not with a minimum value.

This is because the propagation delay can be smaller than typical depending on the direction of current at

the OUTx pin during synchronous switching. Driver propagation delay and dead time can be more than typical

values due to slower internal turn-on of the high-side or low-side internal MOSFETs to avoid parasitic dV/dt

coupling.

For more information and examples of how propagation delay and dead time differs for input PWM and output

configurations, refer to Delay and Dead Time in Integrated MOSFET Drivers .

The dead time from the external microcontroller’s (MCU) PWM inputs (INHx, INLx) can be used as an extra

precaution in addition to the DRV8317 internal shoot-through (cross conduction) protection. If the MCU dead

time is less than the DRV8317 driver dead time, actual output (OUTx voltage) dead time will be decided by

the DRV8317 dead time (tDEAD). If the MCU dead time is larger than the driver dead time, actual output (OUTx

voltage) dead time will be decided by the MCU dead time.

A summary of the DRV8317 delay times with respect to synchronous inputs INHx and INLx, OUTx current

direction, and MCU dead time are listed in Table 9-2.

Table 9-2. Summary of Delay Times in DRV8317 Depending on Logic Inputs and Output Current Direction

OUTx Current

Direction

INHx

INLx

Propagation Delay

(tPD)

Dead Time (tDEAD) Inserted MCU Dead Time (tDEAD(MCU))

tDEAD(MCU) ≤ tDEAD

tDEAD(MCU) > tDEAD

Out of OUTx

Rising

Falling

≤ tPD (max)

≤ tDEAD (max)

Output dead time ≤ tDEAD

(max)

Output dead time = tDEAD(MCU)

Falling

Rising

≤ tPD (typ.)

≤ tDEAD (typ.)

Output dead time ≤ tDEAD

(typ.)

Output dead time < tDEAD(MCU)

DRV8317

SLVSGT3 – DECEMBER 2022

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