Datasheet

LTC3863
29
3863f
For more information www.linear.com/3863
Figure 11. Design Example, 4.5V to 55V Input, ±5V, 1.8A at 320kHz
Positive 5V Efficiency
Negative 5V Efficiency
Positive 5V Gain/Phase
Negative 5V Gain/Phase
TYPICAL APPLICATIONS
16mΩ
L1
12µH
Q1
D1
CAP
0.47µF
PGND
LTC3863
3863 F11a
SS
ITH
FREQ
SGND
RUN
V
IN
PLLIN/MODE
SENSE
GATE
V
FBN
V
FB
10k
52.3k
187k
C
OUT3
100µF
20V
V
OUT
–5V
1.8A
30.1k
D2: DIODES SBR3U100LP-7
L2: TOKO B1134AS-100M
Q2: FAIRCHILD FDMC5614P
C
OUT4
: TDK C4532X5R0J07M
C
OUT5
: PANASONIC EEE-FK1V221P
C
IN1
: CDE AFK686M63G24T-F
C
IN2
: TDK CGA6M3X7S2A475K
C
OUT1
TDK C4532X7R1C336M
C
OUT3
PANASONIC 20SVP100M
D1: VISHAY SS8PH9-M3/87A
L1: MSS1278-123ML
Q1: VISHAY Si7469DP
V
IN
*
4.5V TO 55V
C
IN1
68µF
63V
C
IN2
4.7µF
100V
×2
15nF
220pF
0.1µF0.1µF
0.1µF
C
OUT1
33µF
16V
×2
12pF
25mΩ
L2
10µH
Q2
D2
CAP
0.47µF
PGND
LTC3864
SS
ITH
FREQ
SGND
RUN
V
IN
PLLIN/MODE
SENSE
GATE
PGOOD
V
FB
15k
52.3k
C
OUT5
220µF
35V
C
OUT4
100µF
6.3V
*V
OUT
FOLLOWS V
IN
WHEN 3.5V < V
IN
< 5.2V
NOTE: LTC3863 CAN BE USED IN PLACE
OF LTC3864 IF V
FBN
IS TIED > 2V
V
OUT
*
5V
1.8A
10nF
220pF
422k
80.6k
LTC6908-1
V
+
SYNC1
GND SYNC2
SET MOD
320kHz
316k
+
+
+
Gain/Phase Measurements Taken with OMICRON Lab Bode 100 Vector Network Analyzer.
LOAD CURRENT (A)
0.002
40
EFFICIENCY (%)
POWER LOSS (W)
50
60
70
80
0.02 0.2 2
3863 F11b
30
20
10
0
90
100
4
5
6
7
8
3
2
1
0
9
10
EFFICIENCY
POWER LOSS
V
IN
= 12V
V
OUT
= 5V
PULSE-SKIPPING MODE
Burst Mode OPERATION
FREQUENCY (kHz)
1
–30
GAIN (dB)
PHASE (DEG)
–10
10
30
50
10 100
3863 F11c
70
–20
0
20
40
60
–45
–15
15
0
45
75
105
–30
PHASE
GAIN
30
60
90
LOAD CURRENT (A)
0.002
40
EFFICIENCY (%)
POWER LOSS (W)
60
90
80
0.02 0.2 2
3863 F11d
20
30
50
70
10
0
4
6
9
8
2
3
5
7
1
0
EFFICIENCY
POWER LOSS
V
IN
= 12V
V
OUT
= –5V
PULSE-SKIPPING MODE
Burst Mode OPERATION
FREQUENCY (kHz)
1
–30
GAIN (dB)
PHASE (DEG)
–20
–10
0
10
20
30
40
50
10 100
3863 F11e
60
–45
–30
–15
0
15
30
45
60
75
90
PHASE
GAIN