LT1270C 데이터 시트보기 (PDF) - Linear Technology
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LT1270C Datasheet PDF : 4 Pages
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LT1270A/LT1270
ELECTRICAL CHARACTERISTICS The q denotes specifications which apply over the full operating tempera-
ture range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = VREF, switch pin open, unless otherwise noted.
SYMBOL
ILIM
∆IIN
∆ISW
f
PARAMETER
Switch Current Limit (LT1270A)
(Note 4)
Supply Current Increase
During Switch-ON Time
Switching Frequency
CONDITIONS
Duty Cycle = 50%, TJ ≤ 100°C
Duty Cycle = 80%, TJ ≤ 100°C
DCMAX
Maximum Switch Duty Cycle
Flyback Sense Delay Time
Shutdown Mode Supply Current
Shutdown Mode Threshold Voltage
3V ≤ VIN ≤ VMAX, VC = 0.05V
3V ≤ VIN ≤ VMAX
MIN
q
10.0
q
7.5
50
q
50
80
100
q
50
TYP
MAX
16.0
14.0
25
40
60
70
70
92
95
1.5
100
400
150
250
300
UNITS
A
A
mA/A
kHz
kHz
%
µs
µA
mV
mV
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: Measured with VC in Hi Clamp, VFB = 0.8V.
Note 3: For duty cycles (DC) between 50% and 80%, minimum guaranteed
switch current is given by ILIM = 6.67 (1.7 – DC) for the LT1270 and ILIM =
8.33 (1.7 – DC) for the LT1270A.
Note 4: Minimum current limit is reduced by 0.5A at 125°C. 100°C test
limits are guaranteed by correlation to 125°C tests.
TYPICAL PERFOR A CE CHARACTERISTICS
Switch Current Limit vs Duty Cycle
24
Switch Saturation Voltage
1.6
TJ = 25°C
18
1.2
–55°C
25°C
12
0.8
125°C
6
0.4
0
0
0
20
40
60
80 100
0
DUTY CYCLE (%)
LT1270 • TA03
U
TYPICAL APPLICATIO S
Boost Converter (5V to 12V)
5V
55µH*
VIN
VSW
LT1270
FB
GND
VC
1k
1µF
MBR1020
12V, 2A
10.7k
1.24k
1000µF
25V
PULSE ENGINEERING #PE-92116
LT1270 • TA05
2
4
6
8
10
SWITCH CURRENT (A)
LT1270 • TA04
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 representation that the
interconnection of circuits as described herein will not infringe on existing patent rights.
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