L6566ATR STMicroelectronics, L6566ATR Datasheet - Page 39

• Manufacturer Part Number: L6566ATR
• Description: IC CTRLR OVP UVLO 16SOIC
• Manufacturer: STMicroelectronics

Specifications of L6566ATR

• Output Isolation: Isolated
• Frequency Range: 93 ~ 107kHz
• Voltage - Input: 8 ~ 23 V
• Power (watts): 750mW
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 16-SOIC (0.154", 3.90mm Width)
• For Use With: 497-8834 - BOARD DEMO FOR L6563/LL6566A497-6452 - BOARD EVAL FOR L6566B497-6451 - BOARD EVAL FOR L6566B497-6450 - BOARD EVAL FOR L6566B497-6449 - BOARD EVAL FOR L6566A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6296-2

L6566A
While the brownout protection is active the start-up generator keeps on working but, being
there no PWM activity, the Vcc voltage continuously oscillates between the start-up and the
HV generator restart thresholds, as shown in the timing diagram of
The brownout comparator is provided with current hysteresis in addition to voltage
hysteresis: an internal 15 µA current sink is ON as long as the voltage applied on the
AC_OK pin is such that the AC_FAIL signal is high. This approach provides an additional
degree of freedom: it is possible to set the ON threshold and the OFF threshold separately
by properly choosing the resistors of the external divider (see below). With just voltage
hysteresis, instead, fixing one threshold automatically fixes the other one depending on the
built-in hysteresis of the comparator.
With reference to
the ON (Vsen
Equation 13
which, solved for R
Equation 14
It is typically convenient not to use additional dividers connected to high-voltage rails
because this could make it difficult to meet no-load consumption targets envisaged by
energy-saving regulations.
use of the divider already used by the PFC control chip to sense the ac mains voltage with
just the addition of an extra tap.
The small-signal NPN Q and the capacitor C
of the rms mains voltage can be found across C
to be sensed by the AC_OK pin. It is convenient to use a level as high as possible to
minimize the effect of V
the maximum sensed voltage below 7 V to prevent Q’s emitter reverse breakdown; it would
not be destructive because the reverse current would be quite small (the resistors seen by
Figure 26. AC voltage sensing with the L6566A
L6562/A
L6561
L6563
Vsen
ON
R
H
) and OFF (Vsen
3
ON
Figure 25 on page 38
=
R
H
MULT
input voltage
Vsen
H
−
and R
Rectified
. 0
BE
485
ON
changes with temperature. However, it could be necessary to limit
L
Figure 26
, yield:
−
15
R
R
=
Q
. 1
H
L
15
⋅
078
10
OFF
⋅
10
−
6
⋅
Vsen < 7V
) thresholds of the sensed voltage:
shows a simple voltage sensing technique that makes
Vsen
−
Sensed
voltage:
6
C
, the following relationships can be established for
F
AC_OK
+
. 0
OFF
R
485
F
L
make a peak detector, so that the information
16
;
F
. Tap’s position determines the dc voltage
L6566A
Vcc
R
5
L
=
Vsen
R
H
Vsen
OFF
R
H
−
Application information
OFF
. 0
Figure 25 on page 38
. 0
45
45
−
. 0
=
45
. 0
temperature drift
Q
R
For minimum
45
L
39/51
.