TDA16832G INFINEON [Infineon Technologies AG], TDA16832G Datasheet - Page 6

• Manufacturer Part Number: TDA16832G
• Description: Off-line SMPS Controller with 600 V Sense CoolMOS on Board
• Manufacturer: INFINEON [Infineon Technologies AG]

Circuit Description
The TDA 16831-4 is a current mode pulse
width modulator with integrated sense
CoolMOS
requirements of minimum external control
circuitry for a flyback application.
Current mode control means that the
current through the MOS transistor is
compared with a reference signal derived
from the output voltage of the flyback
application. The result of that comparison
determines the on time of the MOS
transistor.
To minimize external circuitry the sense
resistor which gives information about
MOS current is integrated. The oscillator
resistor and capacitor which determine the
switching frequency are integrated, too.
Special efforts have
compensate temperature dependency and
to minimize tolerances of this resistor.
The circuit in detail: (see Figure 3)
Start Up Circuit (uvlo)
Uvlo is monitoring the external supply
voltage
threshold
bias circuit and the soft start circuit are
switched on. When
off-threshold
switched off. During start up the current
consumption is about 30 A.
Bandgap (bg)
The bandgap generates an internal very
accurate reference voltage of 5.5 V to
supply the internal circuits.
Current Source (bias)
The bias circuit provides the internal
circuits with constant current.
Data Sheet
V
CC
V
. When
CCH
transistor.
V
CCL
= 12 V, the bandgap, the
V
V
= 9 V the circuit is
CC
CC
is exceeding the on
is falling below the
It
been made to
fulfills
the
6
Oscillator (osc)
The oscillator is generating a frequency
twice
f
current source which determine the
frequency are integrated. The charging
and
implemented
internally trimmed, in order to achieve a
very
Temperature
frequency is very low ( see page 19).
Divider Flip Flop (tff)
Tff is a flip flop which divides the oscillator
frequency by one half to create the
switching frequency. The maximum duty
cycle is set to Dmax = 0.5.
Current Sense Amplifier (pwmop)
The positive input of the pwmop is applied
to the internal sense resistor. With the
internal sense resistor (
current coming from the CoolMOS is
converted into a sense voltage. The sense
voltage is amplified with a gain of 32 dB.
The amplified sense voltage is connected
to the negative input of the pwm
comparator. Each time when the CoolMOS
transistor is switched on, a current spike is
superposed to the true current information.
To eliminate this current spike the sense
voltage is smoothed via an internal resistor
capacitor network with a time constant of
T
blanking and only a small spike is left. To
reduce this small spike the current sense
amplifier is creating a virtual ramp at the
output. This is done by a second resistor
capacitor network with
op-offset of 0.8 V which is seen at the
output of the amplifier. When gate drive is
switch
d1
= 100 ns. This is the first leading edge
= 100 kHz. Resistor, capacitor and
accurate
discharging
the
coefficient
oscillator
switching
switching
T
current
R
d2
sense
= 100 ns and an
TDA 16831-4
capacitor
of
) the sensed
frequency.
1999-12-10
frequency
switching
of
the
is