LTC1642 Datasheet, PDF (1/12 Pages) Linear Technology – Hot Swap Controller

Final Electrical Specifications
LTC1642
Hot Swap Controller
May 1999
FEATURES
s _{Single Channel Positive NFET Driver}
s _{Programmable Undervoltage and Overvoltage}
Protection
s _{Foldback Current Limit}
s _{Adjustable Current Limit Time-Out}
s _{Latch Off or Automatic Retry on Current Fault}
s _{Driver for SCR Crowbar on Overvoltage}
s _{Programmable Reset Timer}
s _{Reference Output with Uncommitted Comparator}
s _{VCC: 2.97V to 16.5V Normal Operation, Protected}
Against Surges to 33V.
s _{16-Pin SSOP Package}
U
APPLICATIO S
s _{Hot Board Insertion}
s _{Electronic Circuit Breaker}
DESCRIPTIO
The LTC^®1642 is a 16-pin Hot Swap^TM controller that
allows a board to be safely inserted and removed from a
live backplane. Using an external N-channel pass transis-
tor, the board supply voltage can be ramped up at a
programmable rate. A high side switch driver controls the
N-channel gate for supply voltages ranging from 2.97V to
16.5V.
The SENSE pin allows foldback limiting of the load current,
with circuit breaker action after a programmable delay
time. The delay allows the part to power-up in current
limit. The CRWBR output can be used to trigger an SCR
for crowbar load protection after a programmable delay if
the input supply exceeds a programmable voltage. The
RESET output can be used to generate a system reset with
programmable delay when the supply voltage falls below
a programmable voltage. The ON pin can be used to cycle
the board power. The LTC1642 is available in the 16-pin
SSOP package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
12V
R1
0.010Ω
5%
Q1
FDR9410A
C7
R5
0.1µF
110k
1%
R2
100Ω
5%
R8
330Ω
5%
LATCH OFF: FLOAT FAULT
AUTOMATIC RETRY: TIE FAULT TO ON
16
V_CC
15
SENSE
14
GATE
5
RESET
10
COMPOUT
7
FB
UNDERVOLTAGE = 10.8V
R6
2.87k
1%
OVERVOLTAGE = 13.2V
RESET TIME = 200ms
CURRENT LIMIT TIME = 20ms
CROWBAR TIME = 90µs
R7
11.3k
1%
D1
1N4148
4
ON
LTC1642
6
FAULT
9
OV
GND
BRK TMR
8
2
C3
0.33µF
1
CRWBR
COMP^{– 12}
COMP^{+ 11}
13
REF
RST TMR
3
C5
C2 ^0.1µF
0.33µF
C1
0.047µF
Q2
2N2222
C6
0.01µF
R9
220Ω
5%
12V
+
AT 2.5A
C_LOAD
R3
107k
1%
POWER-GOOD = 11.4V
Q3
MCR
12DC
R4
13k
1%
1642 TA01
R9 REQUIRED ONLY WITH SENSITIVE GATE SCRs,
NOT NEEDED WITH MCR12
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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