Linear Technology Analog Devices LT8708-1 Datasheet page 11

PIN FUNCTIONS
BOOST1, BOOST2 (Pin 24, Pin 19): Boosted Floating
Driver Supply. The (+) terminal of the bootstrap capacitor
connects here. The BOOST1 pin swings from a diode volt-
age below GATEV up to V
CC
pin swings from a diode voltage below GATEV
V + GATEV .
OUT CC
TG1, TG2 (Pin 23, Pin 20): Top Gate Drive. Drives the
top N-channel MOSFETs with voltage swings equal to
GATEV superimposed on the switch node voltages.
CC
SW1, SW2 (Pin 22, Pin 21): Switch Nodes. The (–) ter-
minals of the bootstrap capacitors connect here.
RVSOFF (Pin 25): Reverse Conduction Disable Pin. This
is an input/output open-drain pin that requires a pull-up
resistor. Pulling this pin low disables reverse current oper-
ation. Typically, connect this pin to the LT8708's RVSOFF
pin. See the Unidirectional and Bidirectional Conduction
section for more information.
VOUTLOMON (Pin 26): V
Pin. Connect a ±1% resistor divider between V
VOUTLOMON and GND to set an undervoltage level on
V . When V is lower than this level, reverse conduc-
OUT OUT
tion is disabled to prevent drawing current from V
the Applications Information section for more information.
VINHIMON (Pin 27): V
Connect a ±1% resistor divider between V
and GND in order to set an overvoltage level on V
V is higher than this level, reverse conduction is dis-
IN
abled to prevent current flow into V
Information section for more information.
ICP (Pin 28): Positive V
The voltage on this pin determines the positive V
current for LT8708-1 to regulate to. Connect this pin
to LT8708's ICP pin. See the Applications Information
section for more information.
EXTV (Pin 29): External V
CC
exceeds 6.4V (typical), INTV
pin. When EXTV is lower than 6.4V, the INTV
CC
powered from V . It is recommended to use the same
INCHIP
value bypass cap as the master LT8708.
+ GATEV . The BOOST2
IN CC
CC
Low Voltage Monitor
OUT
OUT
High Voltage Monitor Pin.
IN
, VINHIMON
IN
. When
IN
. See the Applications
IN
Current Command Pin.
OUT
Input. When EXTV
CC
will be powered from this
CC
CC
For more information
CSPOUT (Pin 30): The (+) Input to the V
Monitor Amplifier. This pin and the CSNOUT pin measure
the voltage across the sense resistor, R
the V current signals. It is recommended to use the
OUT
up to same value R
SENSE2
pins as the master LT8708. See Applications Information
section for proper use of this pin.
CSNOUT (Pin 31): The (–) Input to the V
Monitor Amplifier. See Applications Information section
for proper use of this pin.
CSNIN (Pin 32): The (–) Input to the V
Amplifier. This pin and the CSPIN pin measure the volt-
age across the sense resistor, R
V current signals. Connect this pin to V
IN
use. See Applications Information section for proper use
of this pin.
CSPIN (Pin 33): The (+) Input to the V
Monitor Amplifier. Connect this pin to V
in use. See Applications Information section for proper
,
OUT
use of this pin.
V (Pin 34): Main Input Supply Pin for the LT8708-1.
INCHIP
. See It must be locally bypassed to ground. It is recommended
to use the same value bypass cap as the master LT8708.
INTV (Pin 35): 6.35V Regulator Output. Must be con-
CC
nected to the GATEV
EXTV when the EXTV
CC
otherwise INTV
pin to ground with a minimum 4.7µF ceramic capacitor.
It is recommended to use the same value bypass cap as
the master LT8708.
SWEN (Pin 36): Switching Regulator Enable Pin. Tie high
OUT
through a resistor to enable the switching. Ground to dis-
able switching. This pin is pulled down during shutdown, a
thermal lockout or when an internal UVLO (Under Voltage
Lockout) is detected. Do not float this pin. Connect this
CC
pin to the LT8708's SWEN pin for synchronized start-up.
See the Start-Up: SWEN Pin section for more details.
will be
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LT8708-1
SENSE2
between the CSPOUT and CSNOUT
Current Monitor
IN
, to provide the
SENSE1
pin. INTV is powered from
CC CC
voltage is higher than 6.4V,
CC
is powered from V
CC INCHIP .
Current
OUT
, to provide
Current
OUT
when not in
IN
Current
IN
when not
IN
Bypass this
Rev 0
11