TPL7407L

IN3

IN4

OUT1

OUT2

OUT3

OUT4

IN5

IN6

IN7

GND

OUT5

OUT6

OUT7

COM

IN1

IN2

Phase_C

Phase_B

Phase_D

Motor

Phase_A

VSUP

Optional

CCOM

Motor Control Pulses

(1.8 V to 5 V)

11

TPL7407L

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SLRS066D – JANUARY 2014 – REVISED MARCH 2016

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8.2.2 Unipolar Stepper Motor Driver

Figure 11. Stepper Motor Driver Schematic

8.2.2.1 Design Requirements

Figure 11 shows an implementation of TPL7407L for driving a uniploar stepper motor. The unconnected input

channels can be used for other functions. When an input pin is left open the internal 1 M

Ω pull down resistor

pulls the respective input pin to GND potential. For higher noise immunity use an external short across an

unconnected input and GND pins. The COM pin must be tied to the supply of whichever inductive load is being

driven for the driver to be protected by the free-wheeling diode.

Whenever a Zener diode is used between Vcom and the motor supply, the Vcom pin will slew from the coil

supply to a voltage that is the sum of the Zener voltage and the coil supply when there is a flyback event.

Depending on the coil inductance and resistance, this can be very rapid. Whenever the COM pin experiences a

slew rate greater than 0.5 V/µs, a capacitor must be added to limit the slew to < 0.5 V/µs. See Power Supply

Recommendations for further explanation.

8.2.2.2 Detailed Design Procedure

Refer to Design Requirements.

8.2.2.3 Application Curves

Refer to Thermal Characteristics.