STEP

DIR

RESET

nENBL

nHOME

OUT1

OUT2

OUT3

OUT4

Lookup

Table

(translator)

Counter

SM0

SM1

RESET

CLK

DIR

3.3V

DRV8805

www.ti.com

SLVSAW3A

– JULY 2011 – REVISED JULY 2011

FUNCTIONAL DESCRIPTION

Output Drivers

The DRV8805 contains four protected low-side drivers. Each output has an integrated clamp diode connected to

a common pin, VCLAMP.

VCLAMP can be connected to the main power supply voltage, VM. It can also be connected to a zener or TVS

diode to VM, allowing the switch voltage to exceed the main supply voltage VM. This connection can be

beneficial when driving loads that require very fast current decay, such as unipolar stepper motors.

In all cases, the voltage on the outputs must not be allowed to exceed the maximum output voltage specification.

Indexer Operation

The DRV8805 integrates an indexer to allow motor control with a simple step and direction interface. Logically,

the indexer is shown in Figure 2.

Figure 2. Indexer Operation

Step Modes

The SM0 and SM1 pins select the stepping mode of the translator as shown in Table 2.

Table 2. Step Modes

SM1

SM0

MODE

0

0

2-phase drive (full step)

0

1

1-2 phase drive (half step)

1

0

1-phase excitation (wave drive)

1

1

Reserved

In all modes, during a fault condition, the STEP input will be ignored. See the Protection Circuits section below.

The sequence of the outputs is shown in Table 3 through Table 5.

Copyright

© 2011, Texas Instruments Incorporated

Submit Documentation Feedback

7

Product Folder Link(s): DRV8805