Datasheet

© 2006 Microchip Technology Inc. Preliminary DS70178C-page 137
dsPIC30F1010/202X
12.34 APPLICATION EXAMPLES:
12.34.1 STANDARD PWM MODE
In standard PWM mode, the PWM output is typically
connected to a single transistor, which charges an
inductor, as shown in Figure 12-22. Buck and Boost
converters typically use standard PWM mode.
FIGURE 12-22: APPLICATIONS OF
STANDARD PWM MODE
12.34.2 APPLICATION OF COMPLEMENTARY
PWM MODE
Complementary mode PWM is often used in circuits
that use two transistors in a bridge configuration where
transformers are not used, as shown in Figure 12-23.
If transformers are used, then some means must be
provided to ensure that no net DC currents flow
through the transformer to prevent core saturation.
FIGURE 12-23: APPLICATIONS OF
COMPLEMENTARY PWM
MODE
Buck Converter
+V
IN
L1
PWM1H
+
VOUT
Boost Converter
+V
IN
PWM1H
L1
VOUT
+
Period
PWM1H
T
ON T OFF
Inductor charges during T ON
T ON versus Period controls power flow
VOUT
L1
+V
IN
PWM1H
PWM1L
Synchronous Buck Converter
+
+
+V IN
PWM1H
PWM1L
C
R
T1
Series Resonant Half Bridge Converter
L
R
VOUT
PWM1L
PWM1H
Dead Time Dead Time Dead Time
Period