TEA1504 查看數據表（PDF） - Philips Electronics
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TEA1504 Datasheet PDF : 20 Pages
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Philips Semiconductors
GreenChip™ SMPS control IC
Preliminary specification
TEA1504
The start-up current source also helps to implement the
safe-restart or ‘hiccup’ mode required during system fault
conditions: output short-circuit, output open-circuit, and
overvoltage. Under these fault conditions, the IC inhibits
the normal operation of the system and stops delivering
output power. If the output is short-circuited, Caux is no
longer supplied by the auxiliary winding and its voltage
drops to the UVLO level. If the output open-circuits, the
output voltage rises to the Overvoltage Protection (OVP)
level. The IC detects this state and stops switching the
power MOSFET, which stops re-supplying current to Caux
whose voltage starts to drop. Once the voltage on Caux
drops to the UVLO level, the start-up current source
re-activates and charges Caux to the start-up level, and the
system begins the safe-restart mode cycle, similar to the
normal start-up cycle.
Figure 5 shows the relevant waveforms during safe-restart
mode. To achieve a low ‘hiccup’ duty cycle, the current
charging Caux during the safe-restart mode is lower than it
is during normal start-up (see Irestart(Vaux) and Istart(Vaux)H in
Chapter “Characteristics”). This reduces the risk, during
an output short-circuit condition, of any physical damage
being caused to output secondary winding devices, and of
any breach of safety. The start-up current source is also
important for implementing burst mode standby, explained
in Section “Burst mode standby” (see Irestart(Vaux) in
Chapter “Characteristics”).
handbook, full pagewidth
Vmains
Vo
Co
RDEM
OOB 14
1 Vi
DEM 13
2 HVS
n.c. 12
3 n.c.
GND 11 TEA1504 4 DRIVER
n.c. 10
5 Isense
CTRL 9
6 Vaux
REF 8
DS
7
CCTRL RREF
Caux
power
MOSFET
Rsense
(1)
auxiliary
winding
MGS571
(1) Secondary earthing points are isolated from their primary earthing points.
Fig.3 Typical flyback application.
1999 Dec 07
5
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