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PDF LT1248IS Data sheet ( Hoja de datos )
| Número de pieza | LT1248IS | |
| Descripción | Power Factor Controller | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LT1248IS (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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FEATURES
s High Power Factor Over Wide Load Range
with Line Current Averaging
s International Operation Without Switches
s Instantaneous Overvoltage Protection
s Minimal Line Current Dead Zone
s Typical 250µA Start-Up Supply Current
s Rejects Line Switching Noise
s Synchronization Capability
s Low Quiescent Current: 9mA
s Fast 1.5A Peak Current Gate Driver
U
APPLICATIO S
s Universal Power Factor Corrected Power Supplies
s Preregulators Up To 1500W
LT1248
Power Factor Controller
DESCRIPTIO
The LT®1248 provides active power factor correction for
universal off-line power systems. By using fixed high
frequency PWM current averaging, without the need for
slope compensation, the LT1248 achieves far lower line
current distortion with a smaller magnetic element than
systems that use either peak-current detection or zero
current switching approaches in both continuous and
discontinuous modes of operation.
The LT1248 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 LT1248 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 LT1248 provides many protection features including
peak current limiting and overvoltage protection, and can
be operated at frequencies as high as 300kHz.
, LTC and LT are registered trademarks of Linear Technology Corporation.
BLOCK DIAGRA
VAOUT
7
VREF
9
MOUT ISENSE
54
CAOUT PKLIM
32
VCC
16V TO 10V
+
–
2.6V/
EN/SYNC 2.2V
10
VSENSE
11
–
+
IAC 7.5V
6
OVP 7.9V
8
–
EA
+
+
–
SS 12µA
13
5V
7.5V
VREF
RUN
2.2V +
M1
–
7µA
IA
32k
IB
IM
=
IA2 IB
200µA2
IM
– ONE SHOT
+ 200ns
–
+
–
CA
+
+
–
–
+
0.7V
SYNC
RUN
OSC
R
RQ
S
14
CSET
12
RSET
GND VCC
1 15
1 6V
16
GTDR
1248 BD
1
1 page  
TYPICAL PERFOR A CE CHARACTERISTICS
LT1248
GTDR Rise and Fall Time
400
300
200
100
0
0
FALL TIME
RISE TIME
NOTE: GTDR SLEWS
BETWEEN 1V AND 16V
10 20 30 40
LOAD CAPACITANCE (nF)
50
1248 G08
Start-Up Supply Current vs
Supply Voltage
550
500
450
400
350
300 –55°C
250 25°C
200 125°C
150
100
50
0
02
4 6 8 10 12 14 16 18 20
SUPPLY VOLTAGE (V)
1248 G09
Frequency vs RSET and CSET
500
450 RSET = 10k
RSET = 15k
400 RSET = 20k
350 RSET = 30k
300
250
200
150
100
50
0
200 600 1000 1400 1800 2200
CSET CAPACITANCE (pF)
1248 G10
GTDR Maximum Duty Cycle vs
RSET and CSET
1.00
0.99
0.98
0.97
0.96
0.95
0.94
0.93
0.92
0.91
0.90
200
RSET = 10k
RSET = 15k
RSET = 20k
RSET = 30k
600 1000 1400 1800 2200
CSET CAPACITANCE (pF)
1248 G11
Shutdown Mode Supply Current
and Reference Voltage
1.1
1.0 EN/SYNC ≤ 1.8V
1.1
1.0
0.9 0.9
0.8 0.8
0.7 0.7
0.6 0.6
0.5
SUPPLY CURRENT
–55°C ≤ TJ ≤ 25°C
0.5
0.4
TJ = 125°C
0.4
0.3 0.3
0.2
0.1
0
0
0.2
REFERENCE VOLTAGE
TJ ≤ 125°C
0.1
0
16 32
SUPPLY VOLTAGE (V)
1248 G12
Synchronization and Shutdown
Thresholds at EN/SYNC Pin
–44
–40
–36
SHUTDOWN
THRESHOLD
–32
–28
–24
–20
–16
–12
SYNCHRONIZATION
THRESHOLD
TJ = – 55°C
TJ = 25°C
TJ = 125°C
–8
–4
0
0 1 2 3 4 5 6 7 8 9 10
EN/SYNC VOLTAGE (V)
1248 G13
SS Pin Characteristics
–22
–20
–18
–16
–14
–12
–10
–8
–6
–4
–2
0
0
TJ = –55°C
TJ = 25°C
TJ = 125°C
4
SS VOLTAGE (V)
8
1248 G14
MOUT Pin Characteristics
1.5
1.0 TJ = 125°C
TJ = 25°C
0.5 TJ = –55°C
0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
–3.5
–4.0
–2.4
–1.2 0
1.2
MOUT VOLTAGE (V)
2.4
1248 G15
5
5 Page 
LT1248
TYPICAL APPLICATI
300W, 382V Preregulator
90V
TO
270V
T
6A
EMI
FILTER
+
–
750µH*
MURH860
IRF840
1M
1%
VOUT
+
180µF
0.047µF
RS
0.2Ω
20k
1%
20k
1M
4.7nF
50k
0.47µF
330k
RREF
4k
4k 100pF
0.1µF
1nF
20k
VCC
16V TO 10V
+
–
2.6V/2.2V
10
EN/SYNC
11 VSENSE
–
+
6 IAC
8 OVP
7.5V
7.9V
12µA
SS
13
5V
VAOUT
7
9 VREF
7.5V
VREF
RUN
MOUT 5 4 ISENSE 3
CAOUT
PKLIM
2
–
+
2.2V
+
M1
–
7µA
–
EA
+
IA
IB
IM
=
IA2 IB
200µA2
IM
–
CA
+–
+ 32k
–
+
0.7V–
+
RUN
– ONE SHOT
+ 200ns
OSC
SYNC
VCC = 18V**
+
56µF
35V
1 GND
15 VCC
R
RQ
S
16V
GTDR
16
10Ω
1N5819
†
0.01µF
* 1. COILTRONICS CTX02-12236-1 (TYPE 52 CORE)
AIR MOVEMENT NEEDED AT POWER LEVEL GREATER THAN 250W.
2. COILTRONICS CTX02-12295 (MAGNETICS Kool Mµ® 77930 CORE)
** SEE START-UP AND SUPPLY VOLTAGE SECTION FOR VCC GENERATOR.
† THIS SCHOTTKY DIODE IS TO CLAMP GTDR WHEN MOS SWITCH
TURNS OFF. PARASITIC INDUCTANCE AND GATE CAPACITANCE MAY
TURN ON CHIP SUBSTRATE DIODE AND CAUSE ERRATIC OPERATIONS
IF GTDR IS NOT CLAMPED.
CSET
14
1000pF
RSET
12
15k
1248 TA01
Kool Mµ is a registered trademark of Magnetics, Inc.
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.
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LT1248IS.PDF ] | |
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