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LT1249IS8#PBF

P1-P3P4-P6P7-P9P10-P12
LT1249
1
Power Factor Controller
■
Standard 8-Pin Packages
■
High Power Factor Over Wide Load Range
with Line Current Averaging
■
International Operation Without Switches
■
Instantaneous Overvoltage Protection
■
Minimal Line Current Dead Zone
■
Typical 250µA Start-Up Supply Current
■
Rejects Line Switching Noise
■
Synchronization Capability
■
Low Quiescent Current: 9mA
■
Fast 1.5A Peak Current Gate Driver
The 8-pin LT
®
1249 provides active power factor correc-
tion for universal offline power systems with very few
external parts. By using fixed high frequency PWM current
averaging without the need for slope compensation, the
LT1249 achieves far lower line current distortion, with a
smaller magnetic element than systems that use either peak
current detection or zero current switching approach, in
both continuous and discontinuous modes of operation.
The LT1249 uses a multiplier containing a square gain
function from the voltage amplifier to reduce the AC gain
at light output load and thus maintains low line current
distortion and high system stability. The LT1249 also
provides filtering capability to reject line switching noise
which can cause instability when fed into the multiplier.
Line current dead zone is minimized with low bias voltage
at the current input to the multiplier.
The LT1249 provides many protection features including
peak current limiting and overvoltage protection. The
switching frequency is internally set at 100kHz.
While the LT1249 simplifies PFC design with minimal
parts count, the LT1248 provides flexibilities in switching
frequency, overvoltage and current limit.
–
+
–
+
–
+
–
+
–
+
I
M
=
I
A
2
I
B
200µA
2
VA
OUT
7.5V
44µA
22µA
15µA
1V
EA
–
+
32k
I
A
I
B
20µA
250µA MAX
I
M
7.5V
V
REF
+
0.7V
OSC
R
S
Q
6
4
5
32
1
7
8
35pF
I
AC
V
SENSE
M
OUT
R
MOUT
4k
4k
CA
OUT
V
CC
V
CC
16V/10V
CA
MULTIPLIER
RUN
RUN
16V
GND
GTDR
1249 BD
SYNC
M1
g
m
= 1/3k
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
Universal Power Factor Corrected Power Supplies
■
Preregulators up to 1500W
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
BLOCK DIAGRA
W
2
LT1249
ABSOLUTE MAXIMUM RATINGS
W
WW
U
PACKAGE/ORDER INFORMATION
W
U
U
Supply Voltage ....................................................... 27V
GTDR Current Continuous ..................................... 0.5A
GTDR Output Energy (Per Cycle) ............................. 5µJ
I
AC
Input Current ................................................. 20mA
V
SENSE
Input Voltage ............................................ V
MAX
M
OUT
Input Current.............................................. ±5mA
Operating Junction Temperature Range
LT1249C................................................ 0°C to 100°C
LT1249I ........................................... –40°C to 125°C
Thermal Resistance (Junction-to-Ambient)
N8 Package ................................................ 100°C/W
S8 Package................................................. 120°C/W
Storage Temperature Range ..................–65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the operating temperature
range, otherwise specifications are at T
A
= 25°C. Maximum operating voltage (V
MAX
) = 25V, V
CC
= 18V, I
AC
= 100µA, CA
OUT
= 3.5V,
VA
OUT
= 5V, no load on any outputs, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Overall
Supply Current (V
CC
in Undervoltage Lockout) V
CC
= Lockout Voltage – 0.2V ● 0.25 0.45 mA
Supply Current, On 11.5V ≤ V
CC
≤ V
MAX
, CA
OUT
= 1V ● 912 mA
V
CC
Turn-On Threshold ● 15.5 16.5 17.5 V
V
CC
Turn-Off Threshold ● 9.5 10.5 11.5 V
Voltage Amplifier
V
SENSE
Bias Current V
SENSE
= 0V to 7V ● –25 –250 nA
Voltage Amp Gain 70 100 dB
Voltage Amp Unity-Gain Bandwidth 1.5 MHz
Voltage Amp Output High 0 ≤ Source Current ≤ 50µA ● 10 12 V
Voltage Amp Output Low 0 ≤ Sink Current ≤ 5µA ● 0.1 0.4 V
Voltage Amp Source Current ● 130 260 450 µA
Voltage Amp Sink Current Threshold Linear Operation, 2V < VA
OUT
< 10V ● 33 44 57 µA
Voltage Amp Sink Current Hysteresis 2V < VA
OUT
< 10V ● 14 22.5 30 µA
Current Amplifier
Current Amp Offset Voltage ● ±2 ±15 mV
Current Amp Transconductance ∆I
CAOUT
= ±40µA ● 150 320 550 µmho
Current Amp Voltage Gain 2.5V ≤ V
CAOUT
≤ 7.5V 500 1000 V/V
Current Amp Source Current V
MOUT
= 1V, I
M
= 0µA 100 145 220 µA
Current Amp Sink Current V
MOUT
= –0.3V, I
M
= 0µA 67 95 125 µA
Current Amp Output High 7.4 8.1 V
Current Amp Output Low 1.2 2 V
ORDER PART
NUMBER
T
JMAX
= 125°C, θ
JA
= 100°C/W (N8)
T
JMAX
= 125°C, θ
JA
= 120°C/W (S8)
Consult factory for Military grade parts.
LT1249CN8
LT1249IN8
LT1249CS8
LT1249IS8
S8 PART
MARKING
1249
1249I
1
2
3
4
8
7
6
5
TOP VIEW
GND
CA
OUT
M
OUT
I
AC
GTDR
V
CC
V
SENSE
VA
OUT
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE
8-LEAD PDIP
LT1249
3
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Current amplifier is in linear mode with 0V input common mode.
Note 3: Multiplier Gain Constant: K =
Note 4: Maximum GTDR output voltage is internally clamped for higher
V
CC
voltages.
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
FREQUENCY (Hz)
10
GAIN (dB)
100
80
60
40
20
0
–20
100
1k 10k 100k
1249 G01
1M 10M
0
–20
–40
–60
–80
–100
–120
PHASE (DEG)
PHASE
GAIN
Voltage Amplifier Open-Loop
Gain and Phase
FREQUENCY (Hz)
1k
TRANSCONDUCTANCE (µmho)
400
350
300
250
200
150
100
50
0
20
0
–20
–40
–60
–80
–100
–120
–140
100k10k
1249 G02
1M
PHASE (DEG)
10M
g
m
θ
Transconductance of
Current Amplifier
I
M
I
AC
(VA
OUT
– 1.5)
2
PARAMETER CONDITIONS MIN TYP MAX UNITS
Reference
Reference Output Voltage T
A
= 25°C, Measured at V
SENSE
Pin 7.39 7.5 7.6 V
Reference Output Voltage Worst Case All Line, Temperature ● 7.32 7.5 7.68 V
Reference Output Voltage Line Regulation V
LOCKOUT
< V
CC
< V
MAX
● –20 5 20 mV
Multiplier
Multiplier Output Current I
AC
= 100µA, VA
OUT
= 5V 35 µA
Multiplier Output Current Offset R
AC
= 1M from I
AC
to GND ● –0.05 –0.5 µA
Multiplier Max Output Current (I
M(MAX)
)I
AC
= 450µA, VA
OUT
= 7V (Note 2) ● – 375 –250 –150 µA
Multiplier Max Output Voltage (I
M(MAX)
• R
MOUT
)I
AC
= 450µA, VA
OUT
= 7V (Note 2) ● –1.25 –1.1 –0.96 V
Multiplier Gain Constant (Note 3) 0.035 V
–2
I
AC
Input Resistance I
AC
from 50µA to 1mA 15 32 50 kΩ
Oscillator
Oscillator Frequency ● 75 100 125 kHz
Control Pin (CA
OUT
) Threshold Duty Cycle = 0 ● 1.3 1.8 2.3 V
Synchronization Frequency Range Synchronizing Pulse Low ≤ 0.35V on CA
OUT
● 127 160 kHz
Gate Driver
Max GTDR Output Voltage 0mA Load, 18V < V
CC
< V
MAX
(Note 4) ● 12 15 17.5 V
GTDR Output High – 200mA Load, 11.5V ≤ V
CC
≤ 15V ● V
CC
– 3.0 V
GTDR Output Low (Device Unpowered) V
CC
= 0V, 50mA Load (Sinking) ● 0.9 1.5 V
GTDR Output Low (Device Active) 200mA Load (Sinking) ● 0.5 1 V
Peak GTDR Current 10nF from GTDR to GND 1.5 A
GTDR Rise and Fall Time 1nF from GTDR to GND 25 ns
GTDR Max Duty Cycle 90 96 %
ELECTRICAL CHARACTERISTICS
The ● denotes specifications which apply over the operating temperature
range, otherwise specifications are at T
A
= 25°C. Maximum operating voltage (V
MAX
) = 25V, V
CC
= 18V, I
AC
= 100µA, CA
OUT
= 3.5V,
VA
OUT
= 5V, no load on any outputs, unless otherwise noted.
P1-P3P4-P6P7-P9P10-P12

LT1249IS8#PBF

Mfr. #:
Buy LT1249IS8#PBF
Manufacturer:
Analog Devices / Linear Technology
Description:
Power Factor Correction - PFC 8 Pin Pwr Factor Correction Cont
Lifecycle:
New from this manufacturer.
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