Datasheet

5
LT1959
TYPICAL PERFORMANCE CHARACTERISTICS
UW
Switching Frequency
BOOST Pin Current
Maximum Load Current
at V
OUT
= 3.3V
Maximum Load Current
at V
OUT
= 5V
Switch Voltage DropV
C
Pin Shutdown Threshold
Current Limit Foldback
*See “More Than Just Voltage Feedback” in the Applications Information section.
TEMPERATURE (°C)
–50
550
540
530
520
510
500
490
480
470
460
450
100
1959 G11
–25 0 25 50 75 125
FREQUENCY (kHz)
INPUT VOLTAGE (V)
5
2.6
LOAD CURRENT (A)
2.8
3.2
3.4
3.6
9
13
15
4.4
1959 G13
3.0
711
3.8
4.0
4.2
L= 10µH
L= 5µH
L= 3µH
L= 1.8µH
SWITCH CURRENT (A)
0
0
BOOST PIN CURRENT (mA)
10
20
40
30
60
50
12
3
45
1959 G15
80
70
100
90
DUTY CYCLE = 100%
INPUT VOLTAGE (V)
4
4.0
4.2
4.4
12
1959 G14
3.8
3.6
610814
3.4
3.2
3.0
LOAD CURRENT (A)
L= 10µH
L= 5µH
L= 3µH
L= 1.8µH
OUTPUT VOLTAGE (%)
0
5
6
7
80
1959 G16
4
3
20 40 60 100
2
1
0
OUTPUT CURRENT (A)
FOLDBACK
CHARACTERISTICS
CURRENT
SOURCE
LOAD
RESISTOR
LOAD
MOS LOAD
POSSIBLE UNDESIRED
STABLE POINT FOR
CURRENT SOURCE
LOAD*
JUNCTION TEMPERATURE (°C)
–50
1.4
1.2
1.0
0.8
0.6
0.4
100
1959 G17
–25 0 25 50 75 125
THRESHOLD VOLTAGE (V)
SHUTDOWN
SWITCH CURRENT (A)
0
SWITCH VOLTAGE (mV)
250
200
400
125°C
25°C
350
300
45
1959 G18
150
100
50
0
1
2
3
500
450
–40°C
Frequency Foldback
FEEDBACK PIN VOLTAGE (V)
0
SWITCHING FREQUENCY (kHz) OR CURRENT (µA)
500
400
300
200
100
0
0.2
0.4 0.6 0.8
1959 • G10
1.0 1.2
SWITCHING
FREQUENCY
FEEDBACK
PIN CURRENT