TEA1654T NXP Semiconductors, TEA1654T Datasheet - Page 7

• Manufacturer Part Number: TEA1654T
• Manufacturer: NXP Semiconductors

Specifications of TEA1654T

• Operating Temperature (max): 145C
• Operating Temperature (min): -20C
• Pin Count: 14
• Mounting: Surface Mount
• Package Type: SO
• Screening Level: Commercial
• Lead Free Status / Rohs Status: Compliant

Philips Semiconductors
Standby output
The STDBY output pin (V
an external NPN transistor or FET in order to e.g.
switch-off a PFC circuit. The STDBY output is activated by
the internal VCO: as soon as the VCO has reduced the
switching frequency to (almost) the minimum frequency of
24 kHz, the STDBY output will be activated (see Fig.7).
The STDBY output will go low again as soon as the VCO
allows a switching frequency close to the maximum
frequency of 65 kHz.
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.
2003 May 12
handbook, full pagewidth
GreenChip II SMPS control IC
The voltage levels dV
The level at which VCO mode of operation starts or ends can be controlled externally with the VCOadj pin.
V CC(5V)
VCOadj
CTRL
MDB219
1.5 V
1
, dV
5 V
Fig.7 A functional implementation of the standby and cycle skipping circuitry.
V CTRL
2
X2
, dV
STDBY
V x
3
and dV
comparator
current
= 5 V) can be used to drive
V
4
I
are fixed in the IC to typically 50 mV, 18 mV, 40 mV and 15 mV respectively.
OSCILLATOR
DRIVER
DRIVER
I sense
7
Demagnetization recognition is suppressed during the first
time (t
applications where the transformer has a large leakage
inductance and at low output voltages/start-up.
OverVoltage Protection (OVP)
An OVP mode is implemented in the GreenChip series.
For the TEA1654, this works by sensing the auxiliary
voltage via the current flowing into pin DEM during the
secondary stroke. The auxiliary winding voltage is a
well-defined replica of the output voltage. Any voltage
spikes are averaged by an internal filter.
If the output voltage exceeds the OVP trip level, the OVP
circuit switches off the power MOSFET. The controller
then waits until the UVLO level is reached on pin V
When V
recharged to the V
switching again. Subsequently, V
UVLO level, etc.
suppr
CC
). This suppression may be necessary in
drops to UVLO, capacitor C
V STDBY
f max
f min
f osc
skipping
(V)
cycle
5
0
1
0
start
level, however the IC will not start
dV 2
CC
dV 1
dV 3
will drop again to the
Product specification
VCC
dV 4
VCOadj
TEA1654
will be
V x (mV)
V x (mV)
V x (mV)
CC
.