LT4220 Datasheet, PDF (1/16 Pages) Linear Technology – Dual Supply Hot Swap Controller

FEATURES
s _{Hot Swap}^TM _{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 _{–5.2V 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 –2.7V to –16.5V 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
V_CC
–12V
V_EE
V_IN⁺
Z1*
R13
10Ω
C4
100nF
R_S⁺
0.005Ω
Q1
SUB85N03-04
R5
10Ω
C1
R6 _10nF
1k
+
CL1
R1
36.5k
R2
4.99k
R4
4.99k
R3
36.5k
V_IN^–
7
16
15
14
C7
R15
TRACK
20k _{12 ON+}
11 _FAULT
8
V_CC
SENSE⁺ GATE⁺ ₁₀
PWRGD
FB^{+ 13 R16, 20k}
R10
R9
36.5k
10nF
C6
TIMER
4.99k
C8
10nF
1µF
9 _GND
6 _ON–
V_EE
LT4220
R12
FB^{– 5}
4.99k
R11
SENSEK SENSE^– GATE^–
C2
36.5k
1
2
3
4 R8 _10nF
C5
1k
1µF
Z2*
R14
10Ω
R_S^–
0.005Ω
C3
100nF
R7
10Ω
+
CL2
* 1SMA13AT3 TRANSIENT
VOLTAGE SUPPRESSOR
Q2
SUB85N03-04
12V
V_OUT⁺
D1
12V
IN4001 ^VIN⁺
12V
V_OUT+
–12V
V_IN–
D2
–12V
IN4001 _VOUT–
–12V
V_OUT^–
4220 TA01
TIME (10ms/DIV)
4220f
1