LC5540LF Series
Single-Stage Power Factor Corrected
Off-Line Switching Regulators
Features and Benefits
• Integrated on-width control circuit (it realizes high power
factor by average current control)
• Integrated startup circuit (no external startup
circuit necessary)
• Integrated soft-start circuit (reduces power stress during
start-up on the incorporated power MOSFET and rectifier)
• Integrated bias assist circuit (improves the startup
performance, suppresses V
CC
voltage droop during
operation, allows reduction of VCC capacitor value as well
as use of a ceramic capacitor)
• Integrated Leading Edge Blanking (LEB) circuit
• Integrated maximum on-time limit circuit
• Dual-chip structure, with an avalanche-guaranteed power
MOSFET (allows simplified surge suppressing circuits)
• Protection features:
▫
Overcurrent protection (OCP): pulse-by-pulse
▫
Overvoltage protection (OVP): latched shutdown
▫
Overload protection (OLP): latched shutdown
▫
Thermal shutdown (TSD): latched shutdown
Description
LC5540LF series is a quasi-resonant topology switching
power supply IC, designed for input capacitorless applica-
tions, and making it possible for systems to comply with the
harmonics standard (IEC61000-3-2 class C). It incorporates
separate controller and power MOSFET chips. The control-
ler adapts the average current control method for realizing
high power factors, and the quasi-resonant topology contrib-
utes to high efficiency and low EMI noise. The rich set of
protection features helps to realize low component counts,
and high performance-to-cost power supply.
The LC5540LF devices are intended for isolated designs.
The incorporated MOSFET has a V
DSS
(min) rating from
650 V (LC5546LF and LC5547LF) to 800 V (LC5549LF).
The R
DS(on)
(max) is 1.1
Ω
(LC5547LF) to 1.9
Ω
(LC5546LF). It is capable of a maximum output power
of 80 W on 230 VAC supply to 55 W on universal supply
(LC5547LF) based on the thermal rating. Note that the
maximum output power can be up to 120% to 140% of this
value. However, it may be limited in applications with low
output voltage or short duty cycle.
Packages: 7-pin TO-220F
Not to scale
Applications
LF 3052
LF 3051
LF 3054
• LED lighting fixtures
• LED light bulbs
F1
L1
D1
D2
L2
Typical Application
C11
T1
D8
PC2
C9
D9
D5
U1
LC554xLF
C4
DZ2
Control
Part
PC2
R6
D6
C17
DZ1
C12
U2
R1
R9
PC1
R12
C10
Q1
R13
R11
C13
R17
-
+
C14
R16
R14
R15
R18
C15
R19 R20
C16
LED
VAC
C1
D3
D4
C2
C8
R5
R8 R10
D/ST S/GND VCC OCP FB NC OVP
1
C3
C5
R2
(Rocp)
R3
C6
D7
2
3
4
5
6
7
R7
PC1
C7
R4
LC5540LF-DS
LC5540LF
Series
Single-Stage Power Factor Corrected
Off-Line Switching Regulators
Selection Guide
Part
Number
LC5546LF
LC5547LF
LC5549LF
MOSFET
V
DSS
(min)
(V)
650
800
R
DS(on)
(max)
(Ω)
1.9
1.1
1.7
40
17.5
PWM Operation
Frequency, f
OSC
(typ)
(kHz)
On-Time
t
ON(MAX)
(typ)
(μs)
P
OUT
*
(W)
230 VAC
60
80
60
Universal
40
55
40
*Based on the thermal rating; the allowable maximum output power can be up to 120% to 140% of
this value. However, maximum output power may be limited in such an application with low output
voltage or short duty cycle.
The polarity value for current specifies a sink as "+," and a source as “−,” referencing the IC.
Absolute Maximum Ratings
Unless specifically noted, T
A
is 25°C
Characteristic
Drain Current
1
Symbol
LC5546LF
I
DPeak
LC5547LF
LC5549LF
LC5546LF
Single Pulse Avalanche Energy
2
Input Voltage for Control Part (MIC)
OCP Pin Voltage
FB Pin Voltage
OVP Pin Voltage
E
AS
V
CC
V
OCP
V
FB
V
OVP
LC5546LF
Allowable Power Dissipation of
MOSFET
3
P
D1
LC5547LF
LC5549LF
Without heatsink
T
F
Operating Ambient Temperature
Storage Temperature
Channel Temperature
1
Refer
2
Refer
Notes
Single pulse
I
LPeak
= 2.9 A, V
DD
= 99 V, L = 20 mH
I
LPeak
= 4.4 A, V
DD
= 99 V, L = 20 mH
I
LPeak
= 2.8 A, V
DD
= 99 V, L = 20 mH
Pins
1–2
Rating
9.2
13.0
10.5
99
Unit
A
A
A
mJ
mJ
mJ
V
V
V
V
W
W
W
°C
°C
°C
°C
LC5547LF
LC5549LF
1–2
3–2
4–2
5–2
7–2
233
92
35
−2.0
to 5.0
−0.3
to 7.0
−0.3
to 5.0
20.2
With infinite heatsink
1–2
23.6
1.8
―
―
―
―
−20
to 115
−55
to 115
−55
to 125
150
T
OP
T
stg
T
ch
to MOSFET Safe Operating Area Curve.
to MOSFET Avalanche Energy Derating Coefficient Curve.
3
Refer to MOSFET Temperature versus Power Dissipation Curve.
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
LC5540LF-DS
2
LC5540LF
Series
Single-Stage Power Factor Corrected
Off-Line Switching Regulators
Functional Block Diagram
VCC
③
Contol Part
START UP
TSD
UVLO
Reg
Bias
7
OVP ⑥
① D/ST
Drv
② S/GND
S
RQ
OVP
OCP ④
Bottom
Detection
NC ⑥
OCP
LEB
Feedback
Control
Reg
⑤ FB
OSC
OLP
LC554xF Series Terminal List Table
Number
1
2
3
4
5
6
7
Name
D/ST
S/GND
VCC
OCP
FB
NC
OVP
Function
MOSFET drain terminal and input of the startup current
MOSFET source and GND terminal for the Control Part
Supply voltage input and Overvoltage protection (OVP) signal input
Overcurrent Protection, quasi-resonant signal input terminal, and
Overvoltage Protection (OVP) signal input
Feedback signal input and Overload Protection (OLP) signal input
No connection
Overvoltage Protection (OVP) signal input
Pin-out Diagrams
D/ST
S/GND
1
2
3
4
5
6
7
1
2
D/ST
S/GND
VCC
OCP
FB
NC
OVP
D/ST
S/GND
VCC
OCP
FB
NC
OVP
6
1
2
3
4
5
7
(LF 3051)
VCC
OCP
FB
NC
OVP
(LF 3052)
3
4
5
6
7
(LF 3054)
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
LC5540LF-DS
3
LC5540LF
Series
Single-Stage Power Factor Corrected
Off-Line Switching Regulators
Electrical Characteristics of Control Part (MIC)
Unless specifically noted, T
A
is 25°C, V
CC
= 20 V
Characteristic
Power Supply Startup Operation
Operation Start Voltage
Operation Stop Voltage*
Circuit Current in Operation
Startup Circuit Operation Voltage
Startup Current
Startup Current Threshold Biasing
Voltage*
Normal Operation
PWM Operation Frequency
Maximum On-Time
FB Pin Control Minimum Voltage
Maximum Feedback Current
Leading Edge Blanking Time
Quasi-Resonant Operation Threshold
Voltage-1
Quasi-Resonant Operation Threshold
Voltage-2
Protected Operation
OCP Pin Overcurrent Protection
(OCP) Threshold Voltage
OCP Pin Source Current
OCP Pin Overvoltage Protection
(OVP) Operation Voltage
Overload Protection (OLP) Threshold
Voltage
OVP Pin OVP Threshold Voltage
VCC Pin OVP Threshold Voltage
Thermal Shutdown Activating
Temperature
*V
CC(BIAS)
> V
CC(OFF)
always.
V
OCP
I
OCP
V
BD(OVP)
V
FB(OLP)
V
OVP(OVP)
V
CC(OVP)
T
J(TSD)
4–2
4–2
4–2
5–2
7–2
3–2
―
−0.66
−120
2.2
4.1
1.6
28.5
135
−0.60
−40
2.6
4.5
2.0
31.5
–
−0.54
−10
3.0
4.9
2.4
34.0
–
V
μA
V
V
V
V
°C
f
OSC
t
ON(MAX)
V
FB(MIN)
I
FB(MAX)
t
ON(LEB)
V
BD(TH1)
V
BD(TH2)
1–2
1–2
5–2
5–2
4–2
4–2
4–2
33
14
0.50
–40
−
0.14
0.11
40
17.5
0.85
–25
600
0.24
0.16
47
21
1.20
–10
−
0.34
0.21
kHz
μs
V
μA
ns
V
V
V
CC(ON)
V
CC(OFF)
I
CC(ON)
V
STARTUP
I
CC(STARTUP)
V
CC
= 13 V
V
CC(BIAS)
3–2
3–2
3–2
1–2
3–2
3–2
13.8
8.4
–
18
−8.5
9.5
15.1
9.4
–
21
−4.0
11.0
17.3
10.7
4.7
24
−1.5
12.5
V
V
mA
V
mA
V
Symbol
Test Conditions
Pins
Min.
Typ.
Max.
Unit
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
LC5540LF-DS
4
LC5540LF
Series
Single-Stage Power Factor Corrected
Off-Line Switching Regulators
Electrical Characteristics of MOSFET
Unless specifically noted, T
A
is 25°C
Characteristic
Drain-to-Source Breakdown Voltage
Drain Leakage Current
On-Resistance
Symbol
V
DSS
I
DSS
LC5546LF
R
DS(ON)
LC5547LF
LC5549LF
Switching Time
t
f
LC5546LF
LC5547LF
LC5549LF
LC5546LF
Thermal Resistance*
R
θch-F
LC5547LF
LC5549LF
―
1–2
1–2
Test Conditions
LC5546LF
LC5547LF
LC5549LF
Pins
1–2
Min.
650
800
―
―
―
―
―
―
―
―
Typ.
―
―
―
―
―
―
―
―
―
―
Max.
―
―
300
1.9
1.1
1.7
400
300
3.1
2.2
Unit
V
V
μA
Ω
Ω
Ω
ns
ns
°C/W
°C/W
*The thermal resistance between the channels of the MOSFET and the internal frame.
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
LC5540LF-DS
5
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