LT8705_15 Datasheet, PDF (30/44 Pages) Linear Technology – 80V VIN and VOUT Synchronous 4-Switch Buck- Boost DC/DC Controller

LT8705
Applications Information
Input/Output Current Monitoring and Limiting
The LT8705 has independent input and output current
monitor circuits that can be used to monitor and/or limit
the respective currents. The current monitor circuits work
as shown in Figures 10 and 11.
As described in the Topside MOSFET Driver Supply sec-
tion, the CSNIN and CSPOUT pins are also connected
to the Boost Capacitor Charge Control block (also see
Figure 1) and can draw current in certain conditions. In
addition, all four of the current sense pins can draw bias
current under normal operating conditions. As such, do
not place resistors in series with any of the CSxIN or
CSxOUT pins.
FROM DC
POWER SUPPLY
LT8705
R_SENSE1
INPUT
CURRENT
CSPIN CSNIN
g_m = 1mΩ
A7
TO REMAINDER
OF SYSTEM
TO BOOST CAPACITOR
CHARGE CONTROL BLOCK
FAULT
CONTROL
1.61V 1.208V
+
EA2
–
IMON_IN
V_C
R_{IMON_IN}
C_{IMON_IN}
8705 F10
Figure 10. Input Current Monitor and Limit
30
FROM
CONTROLLER
V_OUT
TO BOOST CAPACITOR
CHARGE CONTROL BLOCK
R_SENSE2
OUTPUT
CURRENT
CSPOUT CSNOUT
g_m = 1mΩ
A8
TO SYSTEM V_OUT
LT8705
FAULT
CONTROL
1.61V 1.208V
+
EA1
–
IMON_OUT
V_C
R_{IMON_OUT}
C_{IMON_OUT}
8705 F11
Figure 11. Output Current Monitor and Limit
For more information www.linear.com/LT8705
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