Datasheet

LT1933
5
1933fe
TYPICAL PERFORMANCE CHARACTERISTICS
Frequency Foldback Soft-Start SHDN Pin Current
Typical Minimum Input Voltage Typical Minimum Input Voltage Switch Current Limit
Operating Waveforms
Operating Waveforms,
Discontinuous Mode
FB PIN VOLTAGE (V)
0.0
SWITCHING FREQUENCY (kHz)
700
600
300
100
400
500
200
0
0.5
1933 G10
1.0 1.5
T
A
= 25°C
SHDN PIN VOLTAGE (V)
0
SWITCH CURRENT LIMIT (A)
1.4
1.2
0.6
0.2
0.8
1.0
0.4
0
1
1933 G11
234
T
A
= 25°C
DC = 30%
0
SHDN PIN CURRENT (µA)
200
150
50
100
0
4
1933 G12
81216
SHDN PIN VOLTAGE (V)
T
A
= 25°C
LOAD CURRENT (mA)
5
INPUT VOLTAGE (V)
6
7
8
1933 G13
4
V
OUT
= 5V
T
A
= 25°C
L = 33
µH
TO START
TO RUN
1 10 100
LOAD CURRENT (mA)
4.5
INPUT VOLTAGE (V)
5.0
5.5
6.0
1933 G14
3.0
3.5
4.0
V
OUT
= 3.3V
T
A
= 25°C
L = 22
µH
TO START
TO RUN
1 10 100
TEMPERATURE (°C)
–50
SWITCH CURRENT LIMIT (A)
1.4
1.2
1.0
0.6
0
0.2
0.8
0.4
–25 0 25
1933 G15
50 75 100 150125
V
IN
= 12V, V
OUT
= 3.3V, I
OUT
= 400mA,
L = 22
µH, C
OUT
= 22µF
1933 G16
V
OUT
10mV/DIV
I
L
200mA/DIV
V
OUT1
1.8V
V
OUT2
1.2V
V
SW
10V/DIV
V
IN
= 12V, V
OUT
= 3.3V, I
OUT
= 20mA,
L = 22
µH, C
OUT
= 22µF
1933 G17
V
OUT
10mV/DIV
I
L
200mA/DIV
V
OUT1
1.8V
V
OUT2
1.2V
V
SW
10V/DIV
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