LT1249CS8#PBF Linear Technology, LT1249CS8#PBF Datasheet

IC PFC CTRLR AVERAGE CURR 8SOIC

LT1249CS8#PBF

Manufacturer Part Number
LT1249CS8#PBF
Description
IC PFC CTRLR AVERAGE CURR 8SOIC
Manufacturer
Linear Technology
Datasheet

Specifications of LT1249CS8#PBF

Mode
Average Current
Frequency - Switching
100kHz
Current - Startup
250µA
Voltage - Supply
15.5 V ~ 27 V
Operating Temperature
0°C ~ 100°C
Mounting Type
Surface Mount
Package / Case
8-SOIC (3.9mm Width)
Lead Free Status / RoHS Status
Lead free / RoHS Compliant

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Quantity
Price
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Quantity:
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Company:
Part Number:
LT1249CS8#PBF
Manufacturer:
Linear Technology
Quantity:
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Company:
Part Number:
LT1249CS8#PBF
Manufacturer:
LINEAR/凌特
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FEATURES
BLOCK DIAGRA
APPLICATIO S
, LTC and LT are registered trademarks of Linear Technology Corporation.
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 250 A Start-Up Supply Current
Rejects Line Switching Noise
Synchronization Capability
Low Quiescent Current: 9mA
Fast 1.5A Peak Current Gate Driver
Universal Power Factor Corrected Power Supplies
Preregulators up to 1500W
V
SENSE
I
AC
6
4
7.5V
+
EA
U
VA
W
5
OUT
44 A
22 A
I
I
B
A
32k
1V
+
MULTIPLIER
I
M1
M
=
200 A
I
A
2
I
B
2
15 A
I
M
M
OUT
3
R
4k
250 A MAX
4k
g
MOUT
m
+
CA
= 1/3k
DESCRIPTIO
The 8-pin LT
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.
CA
OUT
2
16V/10V
+
Power Factor Controller
V
+
CC
0.7V
+
SYNC
+
®
1249 provides active power factor correc-
OSC
RUN
U
35pF
GND
1
R
S
20 A
Q
V
7.5V
REF
RUN
16V
LT1249
V
CC
7
GTDR
1249 BD
8
1

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LT1249CS8#PBF Summary of contents

Page 1

... Typical 250 A Start-Up Supply Current Rejects Line Switching Noise Synchronization Capability Low Quiescent Current: 9mA Fast 1.5A Peak Current Gate Driver U APPLICATIO S Universal Power Factor Corrected Power Supplies Preregulators up to 1500W , LTC and LT are registered trademarks of Linear Technology Corporation. W BLOCK DIAGRA VA OUT 5 + 7.5V V ...

Page 2

LT1249 ABSOLUTE MAXIMUM Supply Voltage ....................................................... 27V GTDR Current Continuous ..................................... 0.5A GTDR Output Energy (Per Cycle) ............................. Input Current ................................................. 20mA AC V Input Voltage ............................................ V SENSE M Input Current.............................................. 5mA OUT ...

Page 3

ELECTRICAL CHARACTERISTICS range, otherwise specifications are 5V, no load on any outputs, unless otherwise noted. OUT PARAMETER Reference Reference Output Voltage Reference Output Voltage Worst Case Reference Output Voltage Line Regulation Multiplier Multiplier Output Current Multiplier ...

Page 4

LT1249 W U TYPICAL PERFORMANCE CHARACTERISTICS Reference Voltage vs Temperature 7.536 7.524 7.512 7.500 7.488 7.476 7.464 7.452 7.440 7.428 –75 –50 – JUNCTION TEMPERATURE ( C) Supply Current vs Supply Voltage – ...

Page 5

W U TYPICAL PERFORMANCE CHARACTERISTICS Synchronization Threshold at CA OUT 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 –50 – 125 100 TEMPERATURE ( C) 1249 G11 Voltage Amp Sink Current Limits (Threshold) ...

Page 6

LT1249 PIN FUNCTIONS V (Pin 6): This is the inverting input to the voltage SENSE amplifier. V (Pin 7): This is the supply of the chip. The LT1249 has CC a very fast gate driver required to ...

Page 7

U U APPLICATIONS INFORMATION Line Current Limiting Maximum voltage across R is internally limited to MOUT 1.1V. Therefore, line current limit is 1.1V divided by the sense resistor R . With a 0.2 sense resistor R S current limit is ...

Page 8

LT1249 U U APPLICATIONS INFORMATION The Figure 3 circuit therefore has 382V on V overvoltage level = (V + 44V), or 426V. With OUT hysteresis, V then has to drop 22V to 404V before OUT feedback recovers ...

Page 9

U U APPLICATIONS INFORMATION V = (2)(0.78A)(7 11.5V. If less ripple is desired, P-P higher capacitance should be used. The selection of the output capacitor should also be based on the operating ripple current through the capacitor. The ...

Page 10

LT1249 U U APPLICATIONS INFORMATION voltages above 8V and the 12V limit is only for surge conditions. In normal operation, the voltage into M exceed 1.1V, but under surge conditions, the voltage could temporarily go higher. To date, no field ...

Page 11

... FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...

Page 12

... Complete Solution for Universal Off-Line Switching Power Supplies MURH860 V OUT + 1M 180 F 20k 10 † GND 7.5V V REF RUN + – – RUN OSC SYNC 16V 20 A 35pF sn1249 1249fbs LT/TP 0799 2K REV B • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1994 GTDR 8 ** 1N5819 1249 TA01 ...

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