Datasheet
Overtemperature Protection (OTP)
Smart Sync
Vi
Track
GND VoAdj
Vo
TT
+Sense
−Sense
Inhibit/
UVLO
GND
D
PRE
Vi
GND VoAdj
Vo
TT
+Sense
−Sense
+
Inhibit/
UVLO
Sync
+
+
Q
CLK
SN74LVC2G74
+
SYNC
R
SET1
f
CLK
= 2 x f
MODULE
V
O1
0°
180°
V
CC
CLR
Q
V
O2
C
O1
C
O2
UDG−06054
C
I1
C
I2
R
SET2
Track
V
I
=5 V
PTH04T240W
PTH04T260W
PTH04T260W , PTH04T261W
www.ti.com
.................................................................................................................................................. SLTS273E – SEPTEMBER 2006 – REVISED JULY 2009
A thermal shutdown mechanism protects the module ’ s internal circuitry against excessively high temperatures. A
rise in the internal temperature may be the result of a drop in airflow, or a high ambient temperature. If the
internal temperature exceeds the OTP threshold, the module ’ s Inhibit control is internally pulled low. This turns
the output off. The output voltage drops as the external output capacitors are discharged by the load circuit. The
recovery is automatic, and begins with a soft-start power up. It occurs when the sensed temperature decreases
by about 10 ° C below the trip point.
The overtemperature protection is a last resort mechanism to prevent thermal stress to the regulator.
Operation at or close to the thermal shutdown temperature is not recommended and reduces the long-term
reliability of the module. Always operate the regulator within the specified safe operating area (SOA) limits for
the worst-case conditions of ambient temperature and airflow.
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 of 240 kHz to 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. These are the benefits of Smart Sync. Power
modules can also be synchronized out of phase to minimize source current loading and minimize input
capacitance requirements. Figure 23 shows a standard circuit with two modules syncronized 180 ° out of phase
using a D flip-flop.
Figure 23. Typical SmartSync Circuit
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