Datasheet
LT8705
44
8705fb
For more information www.linear.com/LT8705
LINEAR TECHNOLOGY CORPORATION 2013
LT 0214 REV B • PRINTED IN USA
relaTeD parTs
Typical applicaTion
PART NUMBER DESCRIPTION COMMENTS
LT3791-1 60V High Efficiency (Up to 98%) Synchronous 4-Switch
Buck-Boost DC/DC Controller
4.7V ≤ V
IN
≤ 60V, 1.2V ≤ 60V, Regulates V
OUT
, I
OUT
or I
IN
, TSSOP-38
LTC3789 High Efficiency (Up to 98%) Synchronous 4-Switch
Buck-Boost DC/DC Controller
4V ≤ V
IN
≤ 38V, 0.8V ≤ V
OUT
≤ 38V, SSOP-28, 4mm × 5mm QFN-28
LT3758 High Input Voltage, Boost, Flyback, SEPIC and Inverting
Controller
5.5V ≤ V
IN
≤ 100V, Positive or Negative V
OUT
, 3mm × 3mm DFN-10
or MSOP-10E
LTC3115-1 40V
, 2A Synchronous Buck-Boost DC/DC Converter
2.7V ≤ V
IN
≤ 40V, 2.7V ≤ V
OUT
≤ 40V, 4mm × 5mm DFN-16, TSSOP-20
LTM4609 High Efficiency Buck-Boost DC/DC µModule Regulator
4.5V ≤ V
IN
≤ 36V, 0.8V ≤ V
OUT
≤ 34V, 15mm × 15mm × 2.8mm
12V Output Converter Accepts 4V to 80V Input (5.5V Minimum to Start)
8705 TA03a
CSPOUT
CSNOUT
EXTV
CC
FBOUT
INTV
CC
GATEV
CC
SRVO_FBIN
SRVO_FBOUT
SRVO_IIN
SRVO_IOUT
IMON_IN
IMON_OUT
SYNCCLKOUT
202kHz
V
C
16.5k
CSNIN
TG1 BOOST1
0.22µF 0.22µF
TO DIODE
D
B1
TO DIODE
D
B2
M1
×2
M4
7mΩ
SW1 BG1 CSP CSN
LT8705
GND BG2 SW2 BOOST2
V
OUT
12V
5.0A (V
IN
≥ 5.5V)
4.5A (V
IN
≥ 5.0V)
4.0A (V
IN
≥ 4.5V)
3.5A (V
IN
≥ 4.0V)
V
IN
4V TO 80V
(INCREASED
V
OUT
RIPPLE
FOR V
IN
> 60V)
TG2
CSPIN
V
IN
SHDN
SWEN
LDO33
MODE
FBIN
RT
SS
10nF220pF
215k
38.3k
20k
1µF
1µF
4.7µF
11.3k
C
IN1
: 220µF, 100V
C
IN2
: 4.7µF, 100V, TDK C4532X7S2A475M
C
OUT1A
, C
OUT1B
: 22µF, 25V, TDK C4532X7R1E226M
C
OUT2
: 100µF, 16V, SANYO OS-CON 16SA100M
C
OUT3
: 470µF, 16V
D
B1
, D
B2
: CENTRAL SEMI CMMR1U-02-LTE
L1: 15µH, WURTH 7443631500
M1, M2: FAIRCHILD FDMS86101
M3, M4: FAIRCHILD FDMS7692
*2Ω FROM TG1 TO EACH SEPARATE M1 GATE
102k
C
IN1
C
IN2
×6
C
OUT1A
×2
4Ω
D
B1
D
B2
4.7µF
4.7µF
22nF
TO
BOOST1
100k
4.7µF
2Ω*
+
C
OUT1B
×3
C
OUT2
×2
+
C
OUT3
×3
+
TO
BOOST2
26.1k
M2
15µH
M3
×2
1nF
1nF
4mΩ
10Ω
10Ω
LOAD CURRENT (A)
0
EFFICIENCY (%)
90
95
4
8705 TA03c
85
80
1
2
3
5
100
V
IN
= 60V
V
IN
= 40V
V
IN
= 20V
V
IN
= 12V
V
IN
= 5V
V
OUT
200mV/DIV
V
IN
20V/DIV
10ms/DIVI
LOAD
= 2A
8705 TA03c
Efficiency vs Output Current Input Transient (4V to 80V)
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear.com/LT8705