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