Control IC for Switched-Mode Power Supplies
using MOS-Transistor
TDA 4605-3
Bipolar IC
Features
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Fold-back characteristics provides overload protection for
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external components
Burst operation under secondary short-circuit condition
implemented
Protection against open or a short of the control loop
Switch-off if line voltage is too low (undervoltage switch-off)
Line voltage depending compensation of fold-back point
Soft-start for quiet start-up without noise generated by the
transformer
Chip-over temperature protection implemented (thermal
shutdown)
On-chip ringing suppression circuit against parasitic
oscillations of the transformer
AGC-voltage reduction at low load
P-DIP-8-1
Type
TDA 4605-3
Ordering Code
Q67000-A5066
Package
P-DIP-8-1
The IC TDA 4605-3 controls the MOS-power transistor and performs all necessary control and
protection functions in free running flyback converters. Because of the fact that a wide load range
is achieved, this IC is applicable for consumer as well as industrial power supplies.
The serial circuit and primary winding of the flyback transformer are connected in series to the input
voltage. During the switch-on period of the transistor, energy is stored in the transformer. During the
switch-off period the energy is fed to the load via the secondary winding. By varying switch-on time
of the power transistor, the IC controls each portion of energy transferred to the secondary side
such that the output voltage remains nearly independent of load variations. The required control
information is taken from the input voltage during the switch-on period and from a regulation winding
during the switch-off period. A new cycle will start if the transformer has transferred the stored
energy completely into the load.
Semiconductor Group
74
06.94
INFINEON [ INFINEON TECHNOLOGIES AG ]
