TEA-2261 ST Microelectronics, TEA-2261 Datasheet - Page 7

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

SECURITY FUNCTIONS OF THE TEA2261 (see flow-chart below)
- Undervoltage detection. This protection works
- Overvoltage detection. If V
- Current limitation of the power transistor. The
SECURITY FLOW-CHART (TEA2261)
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 and
the external capacitor C
V
power supply is obtained by reducing V
V
V
power supply" paragraph).In this last case, the
circuit is definitively stopped.
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
CC
CC
C2
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
stop except if the voltage across C
is higher than V
(typically 2.55V) (refer to "Restart of the
CC
is lower than V
threshold reached
Normal operating
CC
C discharged
2
S.M.P.S.
V
reached
starting
2
VIM1
CC
First
stop. Restarting of the
max
is charged as long as
N
N
CC
IM1
exceeds V
CC
) is reached, the
stop (typically
Y
Y
2
CC
reaches
CC
below
max
threshold reached
S.M.P.S. stopped
CC
C charged
V
Definitive
discharged
2
stopping
Second
C2
Reset C
N
VIM2
< 2.6V
Y
Y
- Restart of the power supply. After stopping due
2
- Second current limitation threshold (V
to V
the power supply can be obtained by the normal
operating of the "V
quency from V
due to V
finitively 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.
external capacitor C
voltage across the capacitor reaches V
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.
IM2
N
Y
N
, V
C2
CC
CC
threshold reaching, the circuit is de-
Max or V
below approximately 5V to reset the
Pulse by pulse current
CC
limiting C charged
stop to V
V
C2
< 2.6V
2
CC
CC
N
2
stop triggering, restart of
switch" V
TEA2260 - TEA2261
is charged. When the
CC
start . After stopping
C2
Y
is reached, C
CC
switch se-
C2
(typi-
IM2
2
7/9
is
).