TEA-2261 ST Microelectronics, TEA-2261 Datasheet - Page 6

• Manufacturer Part Number: TEA-2261
• Description: SWITCH MODE POWER SUPPLY CONTROLLER
• Manufacturer: ST Microelectronics

TEA2260 - TEA2261
6/9
SECURITY FUNCTIONS OF THE TEA2260 (see flow-chart below)
- Undervoltage detection. This protection works
- Overvoltage detection. If V
- Current limitation of the power transistor. The
SECURITY FLOW-CHART (TEA2260)
in association with the starting device "V
switch" (see paragraph Starting-mode - standby
mode). If V
7.4V) output pulses are inhibited, in order to avoid
wrong operation of the power supply or bad
power transistor drive.
(typically 15.7V) output pulses are inhibited. Re-
starting of the power supply is obtained by reduc-
ing V
current is measured by a shunt resistor. A double
threshold system is used :
- When the first threshold (V
- Furthermore as long as the first threshold is
conduction of the power transistor is stopped
until the end of the period : a new conduction
signal is needed to obtain conduction again.
reached (it means during several periods), an
external capacitor C
voltage across the capacitor reaches V
CC
below V
CC
is lower than V
CC
stop.
2
is charged. When the
CC
IM1
exceeds V
CC
) is reached, the
threshold reached
Normal operating
C discharged
stop (typically
discharged
2
Reset C
S.M.P.S.
V
reached
starting
CC
VIM1
First
max
N
N
Y
2
C2
CC
(typi-
max
CC
N
Y
Y
- Restart of the power supply. After stopping due
Y
- Second current limitation threshold (V
to V
start of the power supply can be obtained by the
normal operating of the "V
to an integrted counter, if normal restart cannot
be obtained after three trials, the circuit is defini-
tively stopped. In this case it is necessary to
reduce V
circuit. From a practical point of view, it means
that the power supply has to be temporarily dis-
connected from any power source to get the
restart.
cally 2.55V) the output is inhibited. This is called
the "repetitive overload protection". If the over-
load diseappears before V
discharged, so transient overloads are toler-
ated.
When this threshold is reached the output of the
circuit is immediatly inhibited. This protection is
helpfull in case of hard overload for example to
avoid the magnetization of the transformer.
Pulse by pulse current
limiting C charged
threshold reached
S.M.P.S. stopping
V
CC
C2
number = 3
V
N = N + 1
Definitive
stop reached
C2
stopping
Second
, V
Restart
VIM2
< 2.6V
2
CC
N
Y
IM2
N
, V
below approximately 5V to reset the
CC
Max or V
Y
N
CC
CC
C2
stop triggering, re-
switch" but thanks
is reached, C
IM2
2
is
).