TDA4718A Infineon Technologies, TDA4718A Datasheet - Page 4

• Manufacturer Part Number: TDA4718A
• Manufacturer: Infineon Technologies

Specifications of TDA4718A

• Operating Temperature (max): 85C
• Operating Temperature (min): -25C
• Pin Count: 18
• Mounting: Through Hole
• Package Type: PDIP
• Screening Level: Commercial
• Lead Free Status / Rohs Status: Supplier Unconfirmed

Ramp Generator
The ramp generator is triggered by the VCO and oscillates at the same frequency. The
duration of the falling edge of the ramp generator waveform is to be shorter than the fall
time of the VCO. To control the pulse width at the output, the voltage of the rising edge
of the ramp generator signal is compared with a DC voltage at comparator K2. The slope
of the rising edge of the ramp generator signal is controlled by the current through
This offers the possibility of an additional, superimposed control of the output duty cycle.
This additional control capability, called “feed-forward control”, is utilized to compensate
for known interference such as ripple on the input voltage.
Phase Comparator
If the component is operated without external synchronization, the sync input must be
connected to the sync output for the phase comparator to set the rated voltage at
The VCO then oscillates with rated frequency. In the case of external synchronization,
other components can be synchronized with the sync output. The component can be
frequency-synchronized, but not phase-synchronized, with the sync input. The duty
cycle of the squarewave voltage at the sync input is arbitrary. The best stability as to
small phase and frequency interference deviation is achieved with a duty cycle as
offered by the sync output.
Push-Pull Flipflop
The push-pull flipflop is switched by the falling edge of the VCO. This ensures that only
one output of the two push-pull outputs is enabled at a time.
Comparator K2
The two plus inputs of the comparator are switched such that the lower plus level is
always compared with the level of the minus input. As soon as the voltage of the rising
sawtooth edge exceeds the lower of the two plus levels, both outputs are disabled via
the pulse turn-off flipflop. The period during which the respective, active outputs is low
can be infinitely varied. As the frequency remains constant, this process corresponds to
a change in duty cycle.
Pulse-Turn-OFF Flipflop
The pulse turn-OFF flipflop enables the outputs at the start of each half cycle. If an error
signal from comparator K7 or a turn-off signal from K2 is present, the outputs will
immediately be switched off.
Semiconductor Group
4
TDA 4718 A
C
filter
R
R
.
.