Datasheet

5
LT1576/LT1576-5
TYPICAL PERFORMANCE CHARACTERISTICS
U
W
Kool Mµ is a registered trademark of Magnetics, Inc.
JUNCTION TEMPERATURE (°C)
–50
240
220
200
180
160
100
1576 G13
–25 0 25 50 75 125
FREQUENCY (kHz)
Switching Frequency
INPUT VOLTAGE (V)
0
CURRENT (A)
1.50
1.25
1.00
0.75
0.50
0.25
0
5101520
1576 G15
25
V
OUT
= 10V
L = 60µH
L = 30µH
L = 15µH
Maximum Load Current
at V
OUT
= 10V
LOAD CURRENT (mA)
1
INPUT VOLTAGE (V)
7
6
5
10
V
OUT
= 5V
100 1000
1576 G14
MINIMUM
STARTING VOLTAGE
MINIMUM
RUNNING VOLTAGE
Minimum Input Voltage
at V
OUT
= 5V
INPUT VOLTAGE (V)
0
CURRENT (A)
1.50
1.25
1.00
0.75
0.50
0.25
0
5101520
1576 G16
25
V
OUT
= 5V
L = 60µH
L = 30µH
L = 15µH
Maximum Load Current
at V
OUT
= 5V
INDUCTANCE (µH)
05
CORE LOSS (W)
CORE LOSS (% OF 5W LOAD)
1.0
0.1
0.01
0.001
10 15 20
20
12
8
4
2
1.2
0.8
0.4
0.2
0.12
0.08
0.04
0.02
25
1576 G18
TYPE 52
POWDERED IRON
Kool Mµ
®
PERMALLOY
µ = 125
V
OUT
= 5V, V
IN
= 10V, I
OUT
= 1A
CORE LOSS IS
INDEPENDENT OF LOAD
CURRENT UNTIL LOAD CURRENT FALLS
LOW ENOUGH FOR CIRCUIT TO GO INTO
DISCONTINUOUS MODE
Inductor Core Loss
INPUT VOLTAGE (V)
0
CURRENT (A)
1.50
1.25
1.00
0.75
0.50
0.25
0
5101520
1576 G17
25
V
OUT
= 3.3V
L = 30µH
L = 15µH
L = 60µH
Maximum Load Current
at V
OUT
= 3.3V
FEEDBACK VOLTAGE (V)
0
SWITCHING FREQUENCY (kHz)
OR CURRENT (µA)
2.0
1576 G12
0.5
1.0
1.5
250
200
150
100
50
0
FEEDBACK PIN CURRENT
SWITCHING FREQUENCY
Shutdown Supply Current
JUNCTION TEMPERATURE (°C)
–50
TRANSCONDUCTANCE (µMho)
100
1576 G11
050
1600
1400
1200
1000
800
600
400
200
0
–25 25 75 125
Error Amplifier Transconductance Frequency Foldback
SHUTDOWN VOLTAGE (V)
0
INPUT SUPPLY CURRENT (µA)
0.4
1576 G10
0.1
0.2
0.3
100
75
50
25
0
V
IN
= 25V
V
IN
= 10V