Datasheet

LTC3878
5
3878fa
Typical perForMance characTerisTics
Frequency vs Load Current Load Regulation FCM I
TH
Voltage vs Load Current
Current Sense Voltage
vs I
TH
Voltage
On-Time vs I
ON
Current Current Limit Foldback
Maximum V
DS
Current Sense
Threshold vs V
RNG
Voltage
Maximum V
DS
Current Sense
Threshold vs RUN/SS Voltage
Feedback Reference Voltage vs
Temperature
LOAD CURRENT (A)
0
I
TH
VOLTAGE (V)
1.7
2.1
2.5
20
3878 G12
1.3
0.9
1.5
1.9
2.3
1.1
0.7
0.5
5
10
15
25
CONTINUOUS MODE
DISCONTINUOUS MODE
V
IN
= 15V
V
OUT
= 1.2V
FIGURE 7 CIRCUIT
I
ON
CURRENT (µA)
1
10
ON-TIME (ns)
100
1000
10000
10 100
3878 G14
FIGURE 7 CIRCUIT
V
FB
(V)
0
80
100
140
0.6
3878 G15
60
40
0.2 0.4 0.8
20
0
120
MAXIMUM CURRENT SENSE THRESHOLD (mV)
V
RNG
= 1V
FIGURE 7 CIRCUIT
V
RNG
VOLTAGE (V)
0.2
0
MAXIMUM CURRENT SENSE THRESOLD (mV)
50
150
200
250
0.6
1.0
1.2 2.0
3878 G16
100
0.4 0.8
1.4
1.6
1.8
300
RUN/SS VOLTAGE (V)
1.5
140
120
100
80
60
40
20
0
3878 G17
2.0
2.5 3.0
MAXIMUM CURRENT SENSE THRESHOLD (mV)
TEMPERATURE (°C)
–50
FEEDBACK REFERENCE VOLTAGE (V)
0.800
0.802
0.804
110
3878 G18
0.798
0.796
0.792
–10
30
70
–30
10
50
90
0.794
0.808
0.806
I
LOAD
(A)
0
FREQUENCY (kHz)
250
330
410
2 4 6 8
3878 G10
170
90
210
290
370
130
50
10
10 12
14
CONTINUOUS MODE
DISCONTINUOUS MODE
V
IN
= 15V
V
OUT
= 1.2V
FIGURE 7 CIRCUIT
LOAD CURRENT (A)
0
$V
OUT
(%)
–0.10
–0.08
–0.06
3878 G11
–0.12
–0.14
–0.16
5 10
–0.04
–0.02
0
15
V
IN
= 15V
V
OUT
= 1.2V
FIGURE 7 CIRCUIT
I
TH
VOLTAGE (V)
0
–150
CURRENT SENSE THRESHOLD (mV)
–100
0
50
100
1
2
2.5
300
3878 G13
–50
0.5 1.5
150
200
250
V
RNG
= 0.2V
V
RNG
= 0.5V
V
RNG
= 1.0V
V
RNG
= 1.5V
V
RNG
= 2.0V