Datasheet

24
LT3431
sn3431 3431fs
Figure 14a. Dual Polarity Output Converter with all Components Under 3mm Height
V
IN
BOOST
GND V
C
SHDN
SYNC
SW
BIAS
F
B
LT3431EFE
C
F
220pF
C
C
10nF
R
C
1.5k
R2
15.4k
R3
4.99k
L2
CDRH6D28-100
10µH
L1
CDRH6D28-100
10µH
C4
10µF
6.3V
0805
X5R
CER
C6
22µF
6.3V
X5R CER
C3
2.2µF
50V
CER
V
OUT1
V
OUT2
†
–5V AT 0.9A*
V
OUT1
5V AT
1.5A*
V
IN
9V TO 16V
36V TRANSIENT
D1
B140A
D3
B140A
C2
0.22µF
D2
MMSD914T1
C5
22µF
6.3V
X5R CER
3431 F14a
†
FOR LOAD CURRENT LESS THAN 25mA,
A PRELOAD OF 200Ω SHOULD BE USED
TO IMPROVE LOAD REGULATION.
*SEE FIGURE 14c FOR V
OUT1
, V
OUT2
LOAD CURRENT RELATIONSHIP
V
OUT2
LOAD CURRENT (mA)
100
95
90
85
80
75
70
65
60
EFFICIENCY ( %)
3431 F14d
0 200
400
600 800 1000
V
OUT1
AT 1A
V
OUT1
AT 1.5A
V
OUT1
AT 500mA
V
IN
= 12V
Figure 14b. V
OUT2
(–5V) Maximum
Allowable Load Current vs V
OUT1
(5V) Load Current
Figure 14c. V
OUT2
(–5V)
Output Voltage vs Load Current
APPLICATIO S I FOR ATIO
WUUU
Figure 14d. Dual Polarity
Output Converter Efficiency
V
OUT1
LOAD CURRENT (mA)
V
OUT2
LOAD CURRENT (mA)
3431F14b
1200
1000
800
600
400
200
0
0
500
1000
1500
2000
V
IN
= 16V
V
IN
= 12V
V
IN
= 9V
V
OUT2
LOAD CURRENT (mA)
0
|V
OUT2
| (V)
200
400
1000
3431 F14c
600
800
5.30
5.25
5.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
4.80
4/75
4.70
V
OUT1
AT 500mA
V
OUT1
AT 1A
V
OUT1
AT 1.5A
V
IN
= 12V