L6563A STMicroelectronics, L6563A Datasheet - Page 16

• Manufacturer Part Number: L6563A
• Description: IC PFC CTRLR TRANSITION 14SOIC
• Manufacturer: STMicroelectronics

Specifications of L6563A

• Mode: Discontinuous (Transition)
• Current - Startup: 50µA
• Voltage - Supply: 10.3 V ~ 22 V
• Operating Temperature: -25°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Maximum Operating Temperature: + 150 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 25 C
• For Use With: 497-9082 - EVAL BOARD L6563 (200W)497-8850 - BOARD EVAL FOR L6563/STW55NM60N497-8834 - BOARD DEMO FOR L6563/LL6566A497-8429 - BOARD ADAPTER L6599/STP12NM50N497-5854 - DEMO BOARD FOR L6563497-5496 - EVAL BOARD FOR L6599497-5493 - EVAL BOARD FOR L6563
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Application information
6
6.1
16/39
Application information
Overvoltage protection
Normally, the voltage control loop keeps the output voltage V
close to its nominal value, set by the ratio of the resistors R1 and R2 of the output divider.
Neglecting the ripple components, under steady state conditions the current through R1
equals that through R2. Considering that the non-inverting input of the error amplifier is
internally biased at 2.5V, the voltage at pin INV will be 2.5V as well, then:
Equation 1
If the output voltage experiences an abrupt change ∆Vo the voltage at pin INV is kept at 2.5V
by the local feedback of the error amplifier, a network connected between pins INV and
COMP that introduces a long time constant. Then the current through R2 remains equal to
2.5/R2 but that through R1 becomes:
Equation 2
The difference current ∆I
and enter the error amplifier (pin COMP). This current is monitored inside the IC and when it
reaches about 18 µA the output voltage of the multiplier is forced to decrease, thus reducing
the energy drawn from the mains. If the current exceeds 20 µA, the OVP is triggered
(Dynamic OVP), and the external power transistor is switched off until the current falls
approximately below 5 µA. However, if the overvoltage persists (e.g. in case the load is
completely disconnected), the error amplifier will eventually saturate low hence triggering an
internal comparator (Static OVP) that will keep the external power switch turned off until the
output voltage comes back close to the regulated value. The output overvoltage that is able
to trigger the OVP function is then:
Equation 3
R1
= I’
R1
I
- I’
R2
R1
I'
=
R1
∆V
= ∆V
I
R1
O
=
= R1 · 20 · 10
V
--------------------------------------- -
=
O
O
/R1 will flow through the compensation network
2.5
------- -
R2
–
2.5
R1
=
+
V
--------------------- -
∆
O
V
-6
R1
–
O
2.5
O
of the PFC pre-regulator
L6563 - L6563A