TEA2029 STMICROELECTRONICS [STMicroelectronics], TEA2029 Datasheet - Page 34

• Manufacturer Part Number: TEA2029
• Description: APPLICATION NOTE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

TEA2028 - TEA2029 APPLICATION NOTE
Figure 67
V.7.5 - Protection features
As soon as a safety signal (V 1.26V) is applied to
Pin 28, line and supply outputs (Pins 10 and 7) are
both disabled. Capacitor ”C15” begins charging up
until the voltage across it reaches 4V (K
Outputs are again enabled and conduction period
gradually increases as it occurs upon initial start-
up.
The device will be definitively inhibited if the cycle
of events is repeated 3 times.
For the device to restart, the internal 3-bit register
should be reset which requiresthe V
4V (see Figure 68).
Pin 15 charging current : I
Figure 68
Figure 69
34/46
28 s
Pin 15 VOLTAGE (V)
PIN 8
VOLTAGE (V)
PIN 15
VOLTAGE (V)
PIN 7
VOLTAGE
PIN 10 *
VOLTAGE
* Line output (Pin 10) and thyristor cont rol outpu t (Pin 4) for TEA2029C
1.26V
t
1.75
ON
3.3nF
C(AV
1
S
R
3.5
) = - I
1.26
3.5
Q
0
4
LF
D(AV)
CC
Line Inhibition
(Standby Mode)
to fall below
1
= - 3.1 A
10
V
CC
Active area
Soft-start area
).
I
C
Standby
2
Mode
V.7.6 - TV Power supply in standby mode
V.7.6.1 - Regulation by primary controller circuit
This mode of regulation called ”Burst Mode” is
performed only by the primary controller circuit and
is activated in the case of missing control pulses or
in the absence of power supply to TEA2028B.
In this mode, power available through secondary
winding is limited. Refer to TEA2164 Application
Note for further details.
Higher powers can be obtained by using the regu-
lation feature offered by TEA2028B. In this case,
the horizontal output (Pin 10) must be disabled.
V.7.6.2 - Regulation by TEA2028 (see Figure 69)
In this case, all that is required is to disable the line
scanning function thus reducing the overall power
by 90%.
The device power supply regulation loop remains
active, for minimum conduction period to be 1.5ms
the power delivered through secondary must be
higher than 3W.
Line Output Inhibition
Two alternatives are possible :
- Grounding flip-flop Pin 1
- Apply a voltage higher than 3V to Pin 12.
V
L
R1
R2
V
V
12
I
D
+
CC
3
12
6V
3V
Full Inhibition
29 s
TEA2029C
Inverted
1
for
t
t
t
t
10