Datasheet

LT3462/LT3462A
3462af
6
TYPICAL APPLICATIO S
U
Li
+
to –8V Supply
–12V Efficiency
LOAD CURRENT (mA)
0
EFFICIENCY (%)
80
75
70
65
60
55
50
3462 TA02b
1052015 25 3530
T
A
= 25°C
V
IN
= 3.3V
3.3V to –12V with Soft-Start Circuit
V
IN
3.3V
L1
47µH
L2
47µH
R1
267k
R2
27.4k
C3
2.2µF
C
S1
100nF
22nF
C4
15pF
C1
4.7µF
C2
1µF
V
OUT
–12V
30mA
V
IN
SW
FB
SDREF
GND
LT3462
C1: TAIYO YUDEN X5R JMK212BJ475MG
C2: TAIYO YUDEN X5R EMK212BJ105MG
C3: TAIYO YUDEN EMK316BJ225
L1, L2: MURATA LQH32CN470
3462 TA02a
OFF
M1
D
V
IN
2.7V
TO 4.2V
L1A
22µH
L1B
22µH
R1
267k
R2
42.2k
C3
4.7µF
C4
15pF
C1
4.7µF
C2
1µF
V
OUT
–8V
V
IN
SW
FB
SDREF
GND
LT3462
C1: TAIYO YUDEN X5R JMK212BJ475MG
C2: TAIYO YUDEN X5R EMK212BJ105MG
C3: TAIYO YUDEN LMK316BJ475
L1: SUMIDA CLS62-220 OR 2X MURATA LQH32CN330
3462 TA03a
D
LOAD CURRENT (mA)
0
EFFICIENCY (%)
3462 TA03b
20
3010 40
50
80
75
70
65
60
55
50
T
A
= 25°C
V
IN
= 3.3V
–8V Efficiency
2ms/DIV
I
IN
100mA/DIV
OFF
V
OUT
10V/DIV
3462 TA02c
V
OUT
Reaches –12V in 750µs; Input
Current Peaks at 300mA without C
S1
V
OUT
Reaches –12V in 7.5ms; Input
Current Peaks at 125mA with C
S1
= 100nF
2ms/DIV
I
IN
50mA/DIV
OFF
V
OUT
10V/DIV
3462 TA02d