Linear Technology Analog Devices LT8708, Datasheet

Page: 61 / 64

LT8708
61
Rev 0
For more information www.analog.com
Supercapacitor Backup Supply Using CCM
When V
IN
Is Not Applied, V
LOAD
Is Regulated to
11V
When V
IN
Is Applied, V
OUT
Is Charged to
15V
APPLICATIONS INFORMATION
10k
115k
REGULA
TE
CAP
ACITOR TO 15V
LIMIT CAP
ACITOR
CHARGING
CURRENT TO 1A
25m
Ω
25m
Ω
POWER FLOW
8708 T
A06b
V
IN
12V
D
IN
12V LOADS
29k
162k V
BACKUP
INPUT CURRENT IN EXCESS OF 2A WILL DRA
W FROM
SUPERCAP
ACITORS
V
OUT
1.2k
×
6
C
SC ×
6
CSPOUT CSNOUT
EXT
V
CC
FBOUT
INT
V
CC
GA
TEV
CC
IMON_OP
IMON_INP IMON_ON IMON_INN CLKOUT
SYNC
SS
RT
V
C
MODE
CSNIN
TG1
LT8708
TG2
CSPIN V
INCHIP
SHDN FBIN VINHIMON VOUTLOMON SWEN LDO33 RVSOFF DIR
350kHz
ICN ICP
BOOST1
SW1
BG1
CSP
CSN
GND
BG2
SW2
BOOST2
+
+
V
IN
12V
C
IN1
C
IN2
D
IN
LD033
C
OUT1
1.2k ×
6
C
OUT2
C
SC
×
6
V
OUT
15V
8708 T
A06a
5.6nF
124k
1µ
F
220pF
15k
22nF
6.8nF 17.4k
22nF
26.7k
6.8nF
17.4k
17.4k
D
B1
D
B2
TO
BOOST1
TO
BOOST2
4Ω
4.7
µF
10k
4.7
µF
100
Ω
1µ
F
47n
F
115k
25
mΩ
TO DIODE
D
B1
TO DIODE
D
B2
M4
0.22
µF
2Ω
5m
Ω
10
Ω
1nF 1nF
10
Ω
0.22
µF
M3
M2
L1
2.2
μH
2Ω
M1
TO LOADS
(REGULA
TE TO
11V WHEN IN BACKUP)
25
mΩ
100
Ω
1µ
F
4.7
µF
71.5k
162k
20k
20k
20k
200k
150k
50k 50k
M1
–M4:
INFINEON BSC050NE2LS
C
IN1
, C
OUT2
: 220
μF
, 35V 35HVP220M
C
IN2
, C
OUT1
: 22
µF
, 25V
, TDK C4532X741E226M
C
SC
:
60F
, 2.5V COOPER BUSSMAN HB1840-2R5606-R
D
IN
:
APPROPRIA
TE 2A SCHOT
TKY DIODE OR IDEAL DIODE
SUCH AS L
TC4358, L
TC4412, L
TC4352, ETC.
D
B1
, D
B2
:
CENTRAL SEMI CMMR1U-02-L
TE
L1: 2.2
μH, VISHA
Y IHLP-5050CE-01-2R2-M-01
25m
Ω
25m
Ω
POWER FLOW
8708 T
A06c
V
IN
0V
D
IN
LOADS
29k
200k
29k
162k
V
BACKUP
V
OUT
1.2k ×
6
REGULA
TE
LOADS TO 11V
PREVENT CHARGING LOADS > 13.3V