not affect any device functionality. The H-bridge portion still operates normally down to VBB = 8 V with nFAULT

asserted.

8.3.9 Thermal Shutdown (TSD)

Two die-temperature monitors are integrated on the chip. As die temperature increases toward the maximum, a

thermal warning signal is triggered at 160°C. This fault drives the nFAULT low, but does not disable the operation

of the chip. If the die temperature increases further, to approximately 175°C, the full-bridge outputs are disabled

until the internal temperature falls below a hysteresis of 15°C.

8.3.10 Overcurrent Protection

The current flowing through the high-side and low-side drivers is monitored to ensure that the motor lead is not

shorted to supply or ground. If a short is detected, the full-bridge outputs are turned off, flag nFAULT is driven

low, and a 1.2-ms fault timer is started. After this 1.2-ms period, tOCP , the device is then allowed to follow the

input commands and another turnon is attempted (nFAULT becomes high again during this attempt). If there is

still a fault condition, the cycle repeats. If after tOCP expires it is determined the short condition is not present,

normal operation resumes and nFAULT is deasserted.

8.3.11 SENSE

A low-value SENSE resistor is used to set an overcurrent threshold lower than the default maximum value

of 2.8 A and to provide a voltage for VPROPI (DRV8801 Only). This SENSE resistor must be connected

between the SENSE pin and ground. To minimize ground-trace IR drops in sensing the output current level, the

current-sensing resistor should have an independent ground return to the star ground point. This trace should be

as short as possible. For low-value sense resistors, the IR drops in the PCB can be significant, and should be

taken into account.

A direct connection to ground yields a SENSE voltage equal to zero. In that case, maximum current is 2.8 A and

VPROPI outputs 0 V. A resistor connected as explained before, will yield a VPROPI output as detailed in Section

8.3.3. Size the sense resistor such that voltage drop across the sense resistor is less than 500mV under normal

loading conditions. Any voltage equal or larger to 500 mV will signal the device to hi-Z the H-bridge output as

overcurrent trip threshold has been reached. In this case, device will enter recirculation as stipulated by the

MODE input pin. The device automatically retries with a period of t(OCP).

Equation 2 shows the value of the resistor to a particular current setting.

sense

trip

500 mV

R

I

(2)

8.4 Device Functional Modes

8.4.1 Device Operation

The DRV880x supports a low power sleep mode through the nSLEEP pin. In this mode the device shuts down

a majority of the internal circuitry including the internal voltage rails and charge pump. Bringing the nSLEEP pin

HIGH will put the device back into its active state.

During normal operation the DRV880x is designed to operate a single brushed DC motor. The outputs are

connected to each side on the motor coil, allowing for full bidirectional control.

Table 8-1. Control Logic Table(1)

PINS

OPERATION

PHASE

ENABLE

MODE 1

MODE 2

nSLEEP

OUT+

OUT-

1

1

X

X

1

H

L

Forward

0

1

X

X

1

L

H

Reverse

X

0

1

0

1

L

L

Brake (slow decay)

X

0

1

1

1

H

H

Brake (slow decay)

1

0

0

X

1

L

H

Fast-decay synchronous

rectification(2)

www.ti.com

DRV8800, DRV8801

SLVS855K – JULY 2008 – REVISED MARCH 2021

Copyright © 2021 Texas Instruments Incorporated

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