LTC4211IS8 Linear Technology, LTC4211IS8 Datasheet - Page 16

• Manufacturer Part Number: LTC4211IS8
• Description: IC CTRLR HOTSWAP CURR CTRL 8SOIC
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC4211IS8

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: 2.5 V ~ 16.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

OPERATIO
In this fashion, the inrush current is controlled and C
is charged up slowly during the soft-start cycle.
The timing diagram in Figure 6 illustrates the operation of
the LTC4211 in a normal power-up sequence with limited
inrush current as described by Equation 6. At Time Point 5,
the GATE pin voltage begins to ramp indicating that the
power MOSFET is beginning to charge C
Point 5A, the inrush current causes a 50mV voltage drop
across R
ing the inrush current to a fixed level. At Time Point 6, the
GATE pin voltage continues to ramp as C
V
and the internal servo loop disengages. At the end of the
soft-start cycle (Time Point 7), RESET is high and SLOW
COMP is armed.
LTC4211
16
OUT
reaches its final value. The charging current reduces,
SENSE
TIMER
RESET
GATE
I
V
LOAD
V
OUT
ON
CC
and the internal servo loop engages, limit-
1 2
U
CHECK FOR GATE < 0.2V
Figure 6. Normal Power-Up Sequence (With Current Limiting in Second Timing Cycle)
FIRST TIMING CYCLE
PLUG-IN CYCLE
2µA
V
REF
3 4 5
REGULATING AT 50mV/R
CHECK FOR FILTER LOW (<V
CHECK FOR FAULT HIGH (>V
FAST COMPARATOR ARMED
LOAD
LOAD CURRENT IS
SECOND TIMING CYCLE
SOFT-START CYCLE
5A
LOAD
10µA
charges until
. At Time
6
POWER GOOD
V
FB
2µA
> V
SENSE
LOAD
REF
REF
REF
SLOW COMPARATOR ARMED
7 8
+ 50mV)
– 80mV)
FREQUENCY COMPENSATION AT SOFT-START
If the external gate input capacitance (C
600pF, no external gate capacitor is required at GATE to
stabilize the internal current-limiting loop during soft-
start. Otherwise, connect a gate capacitor between the
GATE pin and ground to increase the total gate capacitance
to be equal to or above 600pF. The servo loop that controls
the external MOSFET during current limiting has a unity-
gain frequency of about 105kHz and phase margin of 80°
for external MOSFET gate input capacitances to 2.5nF.
USING AN EXTERNAL GATE CAPACITOR
The LTC4211 automatically limits the inrush current in one
of two ways: by controlling the GATE pin voltage slew rate
GATE
V
OUT
POWER BAD
V
FB
< V
REF
ON GOES LOW
9
10
RESET PULLED LOW DUE TO POWER BAD
200µA
4211 F06
ISS
) is greater than
4211fa