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LT4220 Datasheet, PDF (1/16 Pages) Linear Technology – Dual Supply Hot Swap Controller | |||
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FEATURES
s Hot SwapTM Controller for Positive
and Negative Supplies
s Supply Tracking Mode
s ±2.7V to ±16.5V Operation
s Analog Current Limit with Foldback
s Allows Safe Board Insertion and Removal
from a Live Backplane
s Open-Collector Power Good Comparators
s Automatic Retry or Latchoff After a Current Fault
s Dual Undervoltage Lockout Comparator Inputs
s Current Fault Indication
U
APPLICATIO S
s Live Board Insertion
s RAID Systems
s â5.2V ECL Supplies
s Industrial Controls
s Split Supply Systems
LT4220
Dual Supply
Hot Swap Controller
DESCRIPTIO
The LT®4220 16-pin dual voltage Hot Swap controller
allows a board to be safely inserted and removed from a
live backplane. The device operates with any combination
of 2.7V to 16.5V and â2.7V to â16.5V supplies. Using two
external N-channel pass transistors, the board supply
voltages can be ramped up at an adjustable rate. A select-
able tracking mode allows dual supply tracking control for
ramping the positive and negative supplies together.
The LT4220 features foldback current limit and latches off
both gates if either supply remains in current limit longer
than an adjustable time period. The IC can be configured
for automatic restart after a delay set by the same timer.
A power good signal indicates when the output voltages
monitored by the two FB comparators are within tolerance,
and the gate drive signals are at their full on voltage.
The LT4220 is available in a 16-lead narrow SSOP
package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
±12V 10A Hot Swap Controller
12V
VCC
â12V
VEE
VIN+
Z1*
R13
10â¦
C4
100nF
RS+
0.005â¦
Q1
SUB85N03-04
R5
10â¦
C1
R6 10nF
1k
+
CL1
R1
36.5k
R2
4.99k
R4
4.99k
R3
36.5k
VINâ
7
16
15
14
C7
R15
TRACK
20k 12 ON+
11 FAULT
8
VCC
SENSE+ GATE+ 10
PWRGD
FB+ 13 R16, 20k
R10
R9
36.5k
10nF
C6
TIMER
4.99k
C8
10nF
1µF
9 GND
6 ONâ
VEE
LT4220
R12
FBâ 5
4.99k
R11
SENSEK SENSEâ GATEâ
C2
36.5k
1
2
3
4 R8 10nF
C5
1k
1µF
Z2*
R14
10â¦
RSâ
0.005â¦
C3
100nF
R7
10â¦
+
CL2
* 1SMA13AT3 TRANSIENT
VOLTAGE SUPPRESSOR
Q2
SUB85N03-04
12V
VOUT+
D1
12V
IN4001 VIN+
12V
VOUT+
â12V
VINâ
D2
â12V
IN4001 VOUTâ
â12V
VOUTâ
4220 TA01
TIME (10ms/DIV)
4220f
1
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