DRV8880PWPR datasheet(13/50 Pages) TI2

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AOUT

Step Input

BOUT

Full-scale current

RMS current

DRV8880

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SLVSD18C – JUNE 2015 – REVISED AUGUST 2017

Product Folder Links: DRV8880

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(1)

VMCU is not a pin on the DRV8880, but a supply voltage pullup is required for open-drain output nFAULT; nFAULT may be pulled up to

V3P3

7.3 Feature Description

Table 1 lists the recommended values of the external components.

Table 1. External Components

COMPONENT

PIN 1

PIN 2

RECOMMENDED

CVM1

GND

0.1-µF ceramic capacitor rated for VM per VM pin

CVM1

GND

Bulk electrolytic capacitor rated for VM, recommended value is 100

µF, see Bulk Capacitance Sizing

CVCP

VCP

16-V, 0.47-µF ceramic capacitor

CSW

CPH

CPL

0.1-µF X7R capacitor rated for VM

CV3P3

V3P3

GND

6.3-V, 0.47-µF ceramic capacitor

RnFAULT

VMCU

(1)

nFAULT

> 5 k

Ω pullup

RAISEN

AISEN

GND

Sense resistor, see Sense Resistor

RBISEN

BISEN

GND

7.3.1 Stepper Motor Driver Current Ratings

Stepper motor drivers can be classified using three different numbers to describe the output current: peak, rms,

and full-scale.

7.3.1.1 Peak Current Rating

The peak current in a stepper driver is limited by the overcurrent protection trip threshold IOCP. The peak current

describes any transient duration current pulse, for example when charging capacitance, when the overall duty

cycle is very low. In general the minimum value of IOCP specifies the peak current rating of the stepper motor

driver. For the DRV8880, the peak current rating is 2.5 A per bridge.

7.3.1.2 RMS Current Rating

The rms (average) current is determined by the thermal considerations of the IC. The rms current is calculated

based on the RDS(ON), rise and fall time, PWM frequency, device quiescent current, and package thermal

performance in a typical system at 25°C. The real operating rms current may be higher or lower depending on

heatsinking and ambient temperature. For the DRV8880, the rms current rating is 1.4 A per bridge.

7.3.1.3 Full-Scale Current Rating

The full-scale current describes the top of the sinusoid current waveform while microstepping. Since the

sineusoid amplitude is related to the rms current, the full-scale current is also determined by the thermal

considerations of the IC. The full-scale current rating is approximately

√2 × Irms. The full-scale current is set by

VREF, the sense resistor, and Torque DAC when configuring the DRV8880 , see Current Regulation for details.

For the DRV8880, the full-scale current rating is 2.0 A per bridge.

Figure 12. Full-Scale and rms Current

DRV8880PWPR Datasheet(PDF) 13 Page - Texas Instruments

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