Datasheet

LMD18201
SNVS092D –APRIL 1998–REVISED APRIL 2013 www.ti.com
APPLICATION INFORMATION
TYPES OF PWM SIGNALS
The LMD18201 readily interfaces with different forms of PWM signals. Use of the part with two of the more
popular forms of PWM is described in the following paragraphs.
Simple, locked anti-phase PWM consists of a single, variable duty-cycle signal in which is encoded both
direction and amplitude information (see Figure 9). A 50% duty-cycle PWM signal represents zero drive, since
the net value of voltage (integrated over one period) delivered to the load is zero. For the LMD18201, the PWM
signal drives the direction input (pin 3) and the PWM input (pin 5) is tied to logic high.
Figure 9. Locked Anti-Phase PWM Control
Sign/magnitude PWM consists of separate direction (sign) and amplitude (magnitude) signals (see Figure 10).
The (absolute) magnitude signal is duty-cycle modulated, and the absence of a pulse signal (a continuous logic
low level) represents zero drive. Current delivered to the load is proportional to pulse width. For the LMD18201,
the DIRECTION input (pin 3) is driven by the sign signal and the PWM input (pin 5) is driven by the magnitude
signal.
Figure 10. Sign/Magnitude PWM Control
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