TDA16822 Infineon Technologies, TDA16822 Datasheet - Page 11

• Manufacturer Part Number: TDA16822
• Description: IC OFFLINE CTRLR SMPS CM 8DIP
• Manufacturer: Infineon Technologies
• Series: CoolSET®F1r

Specifications of TDA16822

• Output Isolation: Isolated
• Frequency Range: 93 ~ 107kHz
• Voltage - Input: 9.5 ~ 17 V
• Voltage - Output: 650V
• Power (watts): 20W
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: SP000012897; TDA16822X; TDA16822XK

4 Operation Description
Power Management
The undervoltage lockout monitors the external supply
voltage V
V
reference are switched on. Additionally the error-latch
in the protection unit is reset. The internal bandgap
generates a reference voltage V
the internal circuits. When V
threshold V
power down reset discharges the soft-start capacitor
C
the current consumption is only about 100uA.
Improved Current Mode
- PWM-OP
The input of the PWM-OP is applied to the external
sense resistor R
allows
CoolMOS™ source current with very low tolerance of
maximum current threshold. R
current of the CoolMOS™ into a sense voltage. The
sense voltage is amplified with a gain of 3.65. Then the
amplified signal is superimposed on a virtual ramp of
0.8V. Under low load conditions the source current of
the CoolMOS™ is insufficient to built a voltage ramp for
the PWM-Comparator. To guaranted a proper
operation at low load the virtual ramp is the reference
signal for the PWM-Comparator. The output of the
PWM-OP is connected to the positive inputs of the
PWM-Comparator and the Soft-Start-Comparator.
- PWM-Comparator
The PWM-Comparator compares the sensed current
signal of the CoolMOS™ with the feedback signal V
. V
transistor in combination with the internal pullup
resistor R
feedback circuitry. When the amplified current signal of
the CoolMOS™ exceeds the signal V
Comparator switches off the CoolMOS™.
Soft-Start
The Soft-Start is realized by the internal Soft-Start-
Comparator and pullup resistor R
Start-Comparator compares the voltage at pin SoftS at
the negative input with the ramp-signal of the PWM-OP
at the positive input. When the Soft-Start voltage V
Start
Start-Comparator limits the pulse width by reseting the
driver. The Soft-Start also controls the starting phase of
the hiccup mode by the Comparators C2 and C5 in
case of overload or open loop. The Soft-Start voltage is
generated by an external capacitor C
SoftS and the internal pullup resistor R
charging the external capacitor C
Current Limiting
Version 2.0
CCon
Soft-Start
FB
is less than the Feedback voltage V
=14V, the internal bias circuit and the voltage
is created by an external optocoupler or external
at pin SoftS by switching on T
an
CC
FB
CCoff
. When V
individual
and provides the information of the
=9V the circuit is switched off. Then the
Sense
connected to pin ISense. R
CC
adjustment
exceeds the on-threshold
Sense
CC
Soft-Start
REF
falls below the off-
converts the source
Soft-Start
=6.55V to supply
1
. During start up
.
of
Soft-Start
FB
FB
. The Soft-
the PWM-
Soft-Start
maximum
the Soft-
at pin
Sense
Soft-
by
FB
11
There is a cycle by cycle current limiting realised with
the Current-Limiting Comparator. The CoolMOS™
source current is sensed via an external sense resistor
R
internal threshold voltage V
Comparator immediately turns off the gate drive.
- Propagation Delay Compensation
Concerning circuit delay there is an overshoot of the
peak current I
the peak current. A propagation delay compensation is
integrated to bound the tolerance of the current limiting
at +/-5% plus the tolerances of R
This means the propagation delay time between
exceeding the current sense threshold V
CoolMOS™ switch off is compensated within a range
of
E.g. I
delay compensation the current sense threshold is set
to V
propagation delay time of t
I
compensation the overshoot is only about 2%. A
current ramp of dI/dt=0.1A/us leads to an overshoot of
3% in both cases, with and without compensation. For
further information see Figure 4 on page 8.
Oscillator
The oscillator generates a frequency f
resistor, a capacitor and a current source which
determine the frequency are integrated. The charging
and discharging current of the implemented oscillator
capacitor are internally trimmed, in order to achieve a
very high accuracy switching frequency. The ratio of
controlled charge to discharge current is adjusted to
reach a maximum PWM duty cycle D
PWM-Latch
The oscillator clock output applies a set pulse to the
PWM-Latch
conduction. After setting the PWM-Latch can be reset
by the PWM-OP, the Soft-Start-Comparator, the
Current-Limit-Comparator or the Error-Latch of the
Protection Unit. In case of reseting the driver is shut
down directly.
Driver
The driver-stage drives the gate of the CoolMOS™
and is optimized to minimize EMI and to provide high
circuit efficiency. This is done by reducing the switch on
slope when reaching the CoolMOS™ threshold. Thus
the leading switch on spike is minimized. When
CoolMOS™ is switched off, the falling shape of the
driver is slowed down when reaching 2V to prevent an
overshoot below ground. Furthermore the driver circuit
is designed to eliminate cross conduction of the output
stage.
0
pk
Sense
overshoot of 12%. With the propagation delay
csth
dI
pk
. When the voltage V
dt
=1V. A current ramp of dI/dt=0.4A/us and a
=0.5A at f
0
pk
5 .
when
which depends on the ratio of dI/dt of
A
switch
/
=100kHz. Without propagation
s
initiating
Sense
csth-delay
csth
at R
Sense
=180ns leads to an
the Current-Limit-
the
TDA 16822
CoolSET™
Sense
max
.
switch
11 April 2000
=0.72.
exceeds the
= 100kHz. A
CoolMOS™
csth
and