Linear Technology Analog Devices LT8708, Datasheet

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LT8708
1
Rev 0
For more information www.analog.com
V
BAT2
= 13.5V
I
OUT
= 15A
V
BAT1
(V)
10 12 14 16
94
95
96
97
98
99
100
EFFICIENCY (%)
EFFICIENCY
8708 TA01b
+
–
+
–
CSPOUT
CSNOUT
EXTV
CC
VOUTLOMON
FBOUT
INTV
CC
GATEV
CC
IMON_ON
IMON_OP
ICN
ICP
IMON_INP
IMON_INN
CLKOUT SYNC SS RT
V
C
MODE
CSNIN
TG1 BOOST1 SW1 BG1 CSP CSN
LT8708
GND BG2 SW2 BOOST2 TG2
CSPIN
V
INCHIP
SHDN
FBIN
VINHIMON
SWEN
LDO33
DIR
RVSOFF
126kHz
FWD (3V) RVS (0V)
+ +
D
B1
D
B2
TO
BOOST1
TO
BOOST2
I
LIM
TO DIODE
D
B1
LD033
V
BAT2
8708 TA01a
I
LIM
10V
TO 16V
BATTERY
V
BAT1
10V
TO 16V
BATTERY TO DIODE
D
B2
POWER TRANSFER
DECISION LOGIC
TYPICAL APPLICATION
FEATURES DESCRIPTION
80V Synchronous 4-Switch Buck-Boost DC/DC
Controller with Flexible Bidirectional Capability
The LT
®
8708 is a high performance buck-boost switching
regulator controller that operates from an input voltage
that can be above, below or equal to the output voltage.
Features are included to simplify bidirectional power
conversion in battery/capacitor backup systems and other
applications that may need regulation of V
OUT
, V
IN
, I
OUT
,
and/or I
IN
. Forward and reverse current can be monitored
and limited for the input and output sides of the converter.
All four current limits (forward input, reverse input, forward
output and reverse output) can be set independently using
four resistors on the PCB.
The MODE pin can select between discontinuous conduc-
tion mode (DCM), continuous conduction mode (CCM),
hybrid conduction mode (HCM) and Burst Mode
®
operation.
In combination with the DIR (direction) pin, the chip can be
configured to process power only from V
IN
to V
OUT
or only
from V
OUT
to V
IN
. With a wide 2.8V to 80V input and 1.3V
to 80V output range, the LT8708 is compatible with most
solar, automotive, telecom and battery-powered systems.
12V Bidirectional Dual Battery System with FHCM and RHCM
APPLICATIONS
n
Single Inductor Allows V
IN
Above, Below, or
Equal to V
OUT
n
Six Independent Forms of Regulation
n
V
IN
Current (Forward and Reverse)
n
V
OUT
Current (Forward and Reverse)
n
V
IN
and V
OUT
Voltage
n
Forward and Reverse Discontinuous Conduction
Mode Supported
n
Supports MODE and DIR Pin Changes While Switching
n
V
INCHIP
Range 2.8V (Need EXTV
CC
> 6.4V) to 80V
n
V
OUT
Range: 1.3V to 80V
n
Synchronous Rectification: Up to 99% Efficiency
n
Available in 40-Lead (5mm × 8mm) QFN with High
Voltage Pin Spacing
n
High Voltage Buck-Boost Converters
n
Bidirectional Charging System
n
Automotive 48V Systems
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Efficiency
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