TEA1654T NXP Semiconductors, TEA1654T Datasheet - Page 9

• 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
As soon as the oscillator voltage is high again and the
secondary stroke has ended, the circuit waits for the
lowest drain voltage before starting a new primary stroke.
This method is called valley detection. Figure 8 shows the
drain voltage together with the valley signal, the signal
indicating the secondary stroke and the oscillator signal.
In an optimum design, the reflected secondary voltage on
the primary side will force the drain voltage to zero. Thus,
zero voltage switching is very possible, preventing large
capacitive switching losses
allowing high frequency operation, which results in small
and cost effective inductors.
OverCurrent Protection (OCP)
The cycle-by-cycle peak drain current limit circuit uses the
external source resistor to measure the current accurately.
This allows optimum size determination of the transformer
core (cost issue). The circuit is activated after the leading
edge blanking time t
the ‘sense’ voltage to an internal level.
OverPower Protection (OPP)
During the primary stroke, the rectified mains input voltage
is measured by sensing the current drawn from pin DEM.
This current is dependent on the mains voltage, according
to the following formula:
where:
The current information is used to adjust the peak drain
current, which is measured via pin I
compensation is such that an almost mains independent
maximum output power can be realized.
The OPP curve is given in Fig.9.
2003 May 12
GreenChip II SMPS control IC
N
=
N
----------- -
N
aux
p
leb
. The OCP protection circuit limits
I
DEM
P
=
-------------- -
R
V
1
-- -
2
DEM
aux
sense
C V
. The internal
N V
--------------------------
R
2
DEM
mains
f
, and
9
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, and the IC
will stop switching and enter the safe restart mode.
Short winding protection
After the leading edge blanking time, the short winding
protection circuit is also activated. If the ‘sense’ voltage
exceeds the short winding protection voltage V
converter will stop switching. Once V
UVLO level, capacitor C
supply will restart again. This cycle will be repeated until
the short-circuit is removed (safe restart mode).
The short winding protection will also protect in case of a
secondary diode short-circuit.
handbook, halfpage
MCE406
100 A
(typ)
Fig.9 OPP correction curve.
I DEM
VCC
will be recharged and the
24 A
(typ)
Product specification
CC
drops below the
0.52 V
(typ)
0.3 V
(typ)
V sense(max)
TEA1654
swp
, the