LT8705
TYPICAL APPLICATIONS
L1
22µH
M1
V
48V
5A
OUT
M4
×2
V
IN
36V TO 80V
+
C
IN2
C
+
C
OUT2
C
OUT1
IN1
M3
M2
4.7µF
4.7µF
220µF
220µF
×2
×4
×6
×2
×2
TO
DIODE D
TO
DIODE D
B1
B2
1nF
1nF
10Ω
10Ω
0.22µF
0.22µF
9mΩ
2Ω**
2Ω*
392k
TG1 BOOST1 SW1 BG1 CSP
CSNIN
CSPIN
CSN
GND BG2 SW2 BOOST2 TG2
CSPOUT
CSNOUT
V
IN
EXTV
CC
SHDN
SWEN
LDO33
MODE
FBIN
RT
FBOUT
100k
INTV
10k
CC
CC
GATEV
4.7µF
4.7µF
LT8705
SRVO_FBIN
SRVO_FBOUT
SRVO_IIN
4Ω
71.5k
SS
SRVO_IOUT
IMON_IN
D
D
B2
B1
4.7µF
TO
TO
IMON_OUT
V
BOOST1 BOOST2
CLKOUT
202kHz
SYNC
C
20k
215k
56.2k
4.7µF
1µF
220pF
3.3nF
8705 F14a
C
, C
: 220µF, 100V
*2Ω FROM TG1 TO EACH SEPERATE M1 GATE
**2Ω FROM BG2 TO EACH SEPERATE M3 GATE
IN1 OUT2
C
, C
: 4.7µF, 100V, TDK C453X7S2A475M
IN2 OUT1
, D : CENTRAL SEMI CMMR1U-02-LTE
D
B1 B2
L1: 22µH, WÜRTH 74435572200 OR COILCRAFT SER2918H-223
M1, M3: FAIRCHILD FDMS86104
M2, M4: FAIRCHILD FDMS86101
Efficiency vs Output Current
Efficiency vs Output Current
(Buck Region)
(Boost Region)
100
100
90
V
V
= 36V
V
V
= 72V
IN
OUT
CCM
IN
OUT
CCM
90
= 48V
= 48V
80
70
60
80
70
60
50
40
50
40
30
20
10
0
30
20
10
0
COILCRAFT SER2918H-223
WURTH 74435572200
COILCRAFT SER2918H-223
WURTH 74435572200
10
1000
LOAD CURRENT (mA)
10000
10
1000
LOAD CURRENT (mA)
10000
100
100
8705 F14b
8705 F14c
Note: See the front page and the Typical Performance Characteristics section for more curves from this application
circuit using the Coilcraft inductor. The smaller Würth inductor is also suitable in place of the Coilcraft inductor with
some loss in efficiency.
Figure 14. Telecom Voltage Stabilizer
8705p
40
For more information www.linear.com/8705
Linear [ Linear ]
