V

Load +

D

V

DD

D +

Av VIN)–VIN–

V

DD

H/C

PWM

Load

Voltage

VDD

VDD

VDD

VDD/2

0

0

0

DRV593

DRV594

www.ti.com

SLOS401C – OCTOBER 2002 – REVISED JULY 2010

APPLICATION INFORMATION

PULSE-WIDTH MODULATION SCHEME FOR DRV593 AND DRV594

The pulse-width modulation scheme implemented in the DRV593 and DRV594 eliminates one-half of the full

output filter previously required for PWM drivers. The DRV593 and DRV594 require only one inductor and

capacitor for the output filter. The H/C outputs determine the direction of the current and do not switch back and

forth. The PWM outputs switch to produce a voltage across the load that is proportional to the input control

voltage.

COOLING MODE

Figure 18 shows the DRV593 and DRV594 in cooling mode. The H/C outputs (pins 14-17) are at ground and the

PWM outputs (pins 24-27) create a voltage across the load that is proportional to the input voltage.

The differential voltage across the load is determined using Equation 1 and the duty cycle using Equation 2. The

differential voltage is defined as the voltage measured after the filter on the PWM output relative to the H/C

output.

(1)

(2)

where D duty cycle of the PWM signal Av Gain of DRV593/594 (DRV593: 2.3 V/V, DRV594: 14.5 V/V) VIN+

Positive input terminal of the DRV593/594 VIN– Negative input terminal of the DRV593/594 VDD Power supply

voltage

For example, a 50% duty cycle, shown in Figure 18, results in 2.5 V across the load for VDD = 5 V.

Figure 18. Cooling Mode

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Product Folder Link(s): DRV593 DRV594