LT1507 Просмотр технического описания (PDF) - Linear Technology
Номер в каталоге
Компоненты Описание
производитель
LT1507 Datasheet PDF : 20 Pages
| |||
TYPICAL PERFORMANCE CHARACTERISTICS
Current Limit Foldback
2.5
FOLDBACK
2.0
*POSSIBLE
CHARACTERISTICS
UNDESIRED
STABLE POINT
FOR CURRENT
CURRENT
1.5
SOURCE LOAD
SOURCE LOAD
1.0
0.5
MOS LOAD
RESISTOR LOAD
0
0
20
40
60
80 100
OUTPUT VOLTAGE (%)
LT1507 • TPC13
*SEE "MORE THAN JUST VOLTAGE FEEDBACK"
IN APPLICATIONS INFORMATION SECTION
Maximum Load Current
at VOUT = 3.3V
1.50
VOUT = 3.3V
1.25
L = 10µH
1.00
L = 5µH
0.75
L = 3µH
0.50
L = 2µH
0.25
0
4
6
8
10
12
14
INPUT VOLTAGE (V)
LT1507 • TPC14
Boost Pin Current
12
TJ = 25°C
10
8
6
4
2
0
0 0.25 0.50 0.75 1.00 1.25
SWITCH CURRENT (A)
LT1507 • TPC16
Kool Mµ is a registered trademark of Magnetics, Incorporated.
Metglas is a registered trademark of AlliedSignal Incorporated.
Inductor Core Loss for 3.3V Output
1.0
VOUT = 3.3V
VIN = 5V
IOUT = 1A
0.1
TYPE 52 POWDERED IRON
Kool Mµ®
0.01
PERMALLOY
µ = 125
Metglas®
0.001
1
2
4
6
INDUCTANCE (µH)
8 10
LT1507 • TPC17
CORE LOSS IS INDEPENDENT OF LOAD CURRENT
UNTIL LOAD CURRENT FALLS LOW ENOUGH
FOR CIRCUIT TO GO INTO DISCONTINUOUS MODE
LT1507
Maximum Load Current
at VOUT = 5V
1.50
L = 20µH
1.25
L = 10µH
1.00
L = 5µH
0.75
0.50
0.25
0
0
3
6
9
12
15
INPUT VOLTAGE (V)
LT1507 • TPC15
Switch Voltage Drop
0.8
TJ = 25°C
0.6
0.4
0.2
0
0 0.25 0.50 0.75 1.00 1.25 1.50
SWITCH CURRENT (A)
LT1507 • TPC18
PIN FUNCTIONS
BOOST (Pin 1): The BOOST pin is used to provide a drive
voltage, higher than the input voltage, to the internal
bipolar NPN power switch. Without this added voltage the
typical switch voltage loss would be about 1.5V. The
additional boost voltage allows the switch to saturate and
voltage loss approximates that of a 0.3Ω FET structure,
but with a much smaller die area. Efficiency improves from
70% for conventional bipolar designs to greater than 85%
for these new parts.
VIN (Pin 2): Input Pin. The LT1507 is designed to operate
with an input voltage between 4.5V and 15V. Under certain
conditions, input voltage may be reduced down to 4V.
Actual minimum operating voltage will always be higher
than the output voltage. It may be limited by switch
5
Share Link: 