Datasheet
Smart Sync
GND
PTH08T220W
Track
C
I
1
330 mF
+
UDG-07132
V
I
Sync
TurboTrans
+Sense
V
O
-Sense
+
GND
C
O
1
220 mF
PRE
GND
Q
Q
CLK
CLK
D
V
CC
GND
PTH08T240F
Track
C
I
2
220 mF
+
V
I
Sync
TurboTrans
+Sense
R
SET2
V
O
Adj
V
O
-Sense
+
GND
C
O
2
1000 mF
0°
180°
V
O
2
f
CLK
= 2 x f
MOD
SN74LVC2G74
V
I
= 5 V
V
O
1
R
SET1
V
O
Adj
Inhibit/
UVLO
Inhibit/
UVLO
a
PTH08T240F
SLTS277D – DECEMBER 2006 – REVISED MARCH 2009 ...............................................................................................................................................
www.ti.com
Smart Sync is a feature that allows multiple power modules to be synchronized to a common frequency. Driving
the Smart Sync pins with an external oscillator set to the desired frequency, synchronizes all connected modules
to the selected frequency. The synchronization frequency can be higher or lower than the nominal switching
frequency of the modules within the range between 240 kHz and 400 kHz (see Electrical Specifications table for
frequency limits). Synchronizing modules powered from the same bus, eliminates beat frequencies reflected back
to the input supply, and also reduces EMI filtering requirements. Eliminating the low beat frequencies (usually <
10 kHz) allows the EMI filter to be designed to attenuate only the synchronization frequency. Power modules can
also be synchronized out of phase to minimize source current loading and minimize input capacitance
requirements. If unused, connect the Smart Sync pin to GND (pin 3). Figure 29 shows a standard circuit with two
modules syncronized 180 ° out-of-phase using a D flip-flop.
Figure 29. Smart Sync Schematic
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