tea1533t NXP Semiconductors, tea1533t Datasheet - Page 7

• Manufacturer Part Number: tea1533t
• Description: Greenchiptmii Smps Control Ic
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Demagnetization
The system will be in discontinuous conduction mode all
the time. The oscillator will not start a new primary stroke
until the secondary stroke has ended.
Demagnetization features a cycle-by-cycle output
short-circuit protection by immediately lowering the
frequency (longer off-time), thereby reducing the power
level.
Demagnetization recognition is suppressed during the first
t
applications where the transformer has a large leakage
inductance, at low output voltages and at start-up.
If pin DEM is open-circuit or not connected, a fault
condition is assumed and the converter will stop operating
immediately. Operation will recommence as soon as the
fault condition is removed.
If pin DEM is shorted to ground, again a fault condition is
assumed and the converter will stop operating after the
first stroke. The converter will subsequently enter the safe
restart mode. This situation will persist until the
short-circuit is removed.
2002 Aug 23
suppr
handbook, full pagewidth
GreenChip
The voltage levels dV
time. This suppression may be necessary in
CTRL
1.5 V
TM
150 mV
V CTRL
1
V x
and dV
X2
II SMPS control IC
2
comparator
are fixed in the IC to 50 mV (typical) and 18 mV (typical) respectively.
current
V
I
OSCILLATOR
DRIVER
Fig.7 The cycle skipping circuitry.
I sense
DRIVER
7
Minimum and maximum ‘on-time’
The minimum ‘on-time’ of the SMPS is determined by the
Leading Edge Blanking (LEB) time. The IC limits the
‘on-time’ to 50 s. When the system desires an ‘on-time’
longer than 50 s, a fault condition is assumed (e.g.
removed C
the safe restart mode.
i
in Fig.11), the IC will stop switching and enter
f max
f min
f osc
skipping
cycle
1
0
TEA1533T; TEA1533AT
dV 2
dV 1
Product specification
150
V x (mV)
MGU510
V x (mV)