LTC4261 Datasheet, PDF (1/32 Pages) Linear Technology – Negative Voltage Hot Swap Controllers with ADC and I2C Monitoring

LTC4261/LTC4261-2
Negative Voltage
Hot Swap Controllers with
ADC and I²C Monitoring
FEATURES
DESCRIPTION
■ _{Allows Safe Insertion into Live –48V Backplanes}
■ _{10-Bit ADC Monitors Current and Voltages}
■ _I²_{C/SMBus Interface or Single-Wire Broadcast Mode}
■ _{Floating Topology Allows Very High Voltage}
Operation
■ _{Independently Adjustable Inrush and Overcurrent}
Limits
■ _{Controlled Soft-Start Inrush}
■ _{Adjustable UV/OV Thresholds and Hysteresis}
■ _{Sequenced Power Good Outputs with Delays}
■ _{Adjustable Power Good Input Timeout}
■ _{Programmable Latchoff or Auto-Retry After Faults}
■ _{Alerts Host After Faults}
■ _{Available in 28-Lead Narrow SSOP and 24-Lead}
(4mm × 5mm) QFN Packages
APPLICATIONS
■ _{AdvancedTCA Systems}
■ _{Telecom Infrastructure}
■ _{–48V Distributed Power Systems}
■ _{Power Monitors}
The LTC^®4261/LTC4261-2 negative voltage Hot Swap^TM
controllers allow a board to be safely inserted and removed
from a live backplane. Using an external N-channel pass
transistor, the board supply voltage can be ramped at an
adjustable rate. The devices feature independently adjust-
able inrush current and overcurrent limits to minimize
stresses on the pass transistor during start-up, input
step and output short conditions. The LTC4261 defaults
to latch-off while the LTC4261-2 defaults to auto-retry on
overcurrent faults.
An I²C interface and onboard 10-bit ADC allow monitoring
of board current, voltage and fault status. A single-wire
broadcast mode is available to simplify the interface by
eliminating two optoisolators.
The controllers have additional features to interrupt the
host when a fault has occurred, notify when output power
is good, detect insertion of a board and turn off the pass
transistor if an external supply monitor fails to indicate
power good within a timeout period.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation. Patents pending.
All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
–48V/200W Hot Swap Controller with I²C and ADC
–48V RTN
453k
1%
4× 1k IN SERIES
1/4W EACH
UV = 38.5V
UV RELEASE
AT 43V
OV = 72.3V
OV RELEASE
AT 71V
16.9k
1%
11.8k
1%
1µF
–48V INPUT
UVL
V_IN
PGI
UVH
ALERT
ADIN2
OV
INTV_CC
ON
LTC4261CGN
SDAO
SDAI
SCL
ADIN
PGIO
V_IN+ ⁺
LOAD
SS
TMR EN V_EE SENSE GATE DRAIN RAMP ^PG
ON
V_IN–
220nF
47nF
10Ω
1M 1k
10nF
0.1µF 47nF
0.008Ω
1%
100V
5% _VOUT
Q1
IRF1310NS
42612 TA01
–48V INPUT
50V/DIV
330µF
100V
V_OUT
50V/DIV
SENSE
0.5A/DIV
PG
50V/DIV
Start-Up Behavior
10ms/DIV
42612 TA01b
42612fb
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