L6566ATR STMicroelectronics, L6566ATR Datasheet - Page 25

• 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
5.4
Figure 13.
COMP
Figure 12. Addition of an offset to the current sense lowers the burst-mode
Adaptive UVLO
A major problem when optimizing a converter for minimum no-load consumption is that the
voltage generated by the auxiliary winding under these conditions falls considerably as
compared even to a few mA load. This very often causes the supply voltage Vcc of the
control IC to drop and go below the UVLO threshold so that the operation becomes
intermittent, which is undesired. Furthermore, this must be traded off against the need of
generating a voltage not exceeding the maximum allowed by the control IC at full load.
To help the designer overcome this problem, the device, besides reducing its own
consumption during burst-mode operation, also features a proprietary adaptive UVLO
function. It consists of shifting the UVLO threshold downwards at light load, namely when
the voltage at pin COMP falls below a threshold V
Interface"), so as to have more headroom. To prevent any malfunction during transients from
minimum to maximum load the normal (higher) UVLO threshold is re-established when the
voltage at pin COMP exceeds V
Vcc has exceeded the normal UVLO threshold (see
ensures that at full load the MOSFET will be driven with a proper gate-to-source voltage.
Adaptive UVLO block
(*) Vcc
9
V
V
COMPL
COMPO
OFF2
< Vcc
-
+
OFF1
is selected when Q is high
Vcc_PFC
Vcc_PFC
logic
operation threshold
6
R
S
Vcc
Q
OFF1
+
-
Vref
Vcc
L6566A
SW
(*)
OFF2
COMPL
Vcc
10
5
+
-
3
UVLO
L6566A
(see "
7
4
Vcs
o
Chapter 5.8: PFC interface on page 31
= Vref
Vcc_PFC
VCOMP
(pin 6)
(pin 9)
(pin 5)
Vcc
Vcc
V
V
Vcc
Rc
COMPL
COMPO
COMPO
OFF1
OFF2
R + Rc
Q
Figure 13
R
R
internally fixed (see "PFC
Tdelay
). The normal UVLO threshold
Rs
Application information
t
t
t
t
") and
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