L6699D STMicroelectronics, L6699D Datasheet - Page 30

• Manufacturer Part Number: L6699D
• Description: AC/DC Switching Converters Enhanced High Volt Res CTRL 600V
• Manufacturer: STMicroelectronics
• Type: High Voltage Controllersr

Specifications of L6699D

• Product Category: AC/DC Switching Converters
• Output Voltage: 13.3 V
• Input / Supply Voltage (max): 8.85 V
• Input / Supply Voltage (min): 16 V
• Switching Frequency: 235 kHz
• Supply Current: 3 mA
• Operating Temperature Range: - 25 C to + 125 C
• Mounting Style: SMD/SMT
• Package / Case: SO-16
• Number Of Outputs: 1
• Output Current: 800 mA

Line sensing function
10
30/38
Line sensing function
This function basically stops the IC as the input voltage to the converter falls below the
specified range and lets it restart as the voltage goes back within the range. The sensed
voltage can be either the rectified and filtered mains voltage, in which case the function acts
as a brownout protection, or, in systems with a PFC pre-regulator front-end, the output
voltage of the PFC stage, in which case the function serves as a power-on and power-off
sequencing.
L6699 shutdown upon input undervoltage is accomplished by means of an internal
comparator, as shown in the block diagram of
available at pin 7 (LINE). The comparator is internally referenced to 1.22 V and disables the
IC if the voltage applied at the LINE pin is below the internal reference. Under these
conditions the soft-start is discharged, the PFC_STOP pin is open and the consumption of
the IC is reduced. PWM operation is re-enabled as the voltage on the pin is above the
reference. The comparator is provided with current hysteresis instead of a more usual
voltage hysteresis: an internal 13 µA current sink is ON as long as the voltage applied at the
LINE pin is below the reference and is OFF if the voltage is above the reference.
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 voltage hysteresis, on the other hand, fixing one threshold
automatically fixes the other one depending on the built-in hysteresis of the comparator.
With reference to
(Vin
Equation 12
which, solved for R
Equation 13
ON
) and OFF (Vin
Vin
Figure 22
ON
R
H
R
H
and R
-
H
OFF
. 1
=
25
) thresholds of the input voltage:
Vin
L
, the following relationships can be established for the ON
, yields:
13
=
ON
Doc ID 022835 Rev 2
13
·
-
10
Vin
·
10
6
OFF
-
6
+
. 1
R
;
25
L
Figure 22
R
L
;
=
R
Vin
H
, whose non-inverting input is
Vin
OFF
R
OFF
H
. 1
-
. 1
25
-
25
. 1
25
=
. 1
R
25
L
L6699