Independent Control of Main and Auxiliary Supplies
20V Rating for 12V Supply Input Pins
Integrated 0.25Ω AUX Switches
Limits Fault Current in ≤1µs
Force On Test Mode
Adjustable Supply Voltage Power-Up Rate
High Side Drivers for N-Channel MOSFETs
Thermal Shutdown Protection
Available in 38-Lead QFN and 36-Lead SSOP
Packages
The LTC
®
4242 Hot Swap
TM
controller allows safe board
insertion and removal for two independent slots on a PCI
Express backplane. External N-channel transistors control
the 12V and 3.3V supplies while integrated switches control
the 3.3V auxiliary supplies. Both 12V and 3.3V supplies
can be ramped up at an adjustable rate. Dual level circuit
breakers and fast active current limiting protect all supplies
against overcurrent faults.
A supply filter at the V
CC
pin allows the LTC4242 to endure
supply transients. The EN input detects the presence of a
card in the PCI Express slot. The FAULT and AUXFAULT
outputs alert the system of overcurrent conditions on the
main and auxiliary supplies, respectively. PGOOD and
AUXPGOOD outputs indicate proper main and auxiliary
supply outputs.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
APPLICATIO S
■
■
PCI Express-Based PC and Servers
Hot Swap Application for Triple Supply Systems
TYPICAL APPLICATIO
12V
3.3V
PCI Express Application
12V
OUT
3.3V
OUT
12V
IN1
12V
SENSE1
12V
GATE1
12V
OUT1
3V
IN1
V
CC
3V
SENSE1
3V
GATE1
3V
OUT1
AUXOUT1
3.3V
OUT
BD_PRST1
ENn
5V/DIV
AUXOUTn
5V/DIV
3.3V
AUXIN1
AUXON1
ON1
FAULT1
AUXFAULT1
PGOOD1
PGOOD2
AUXFAULT2
FAULT2
ON2
AUXON2
AUXIN2
12V
IN2
12V
SENSE2
12V
GATE2
12V
OUT2
3V
IN2
PCI EXPRESS
HOT PLUG
CONTROLLER
LTC4242G
FON1
EN1
GND
EN2
FON2
PCIe
PLUG-IN
CONNECTOR CARD
12V
OUTn
5V/DIV
3V
OUTn
5V/DIV
BD_PRST2
AUXOUT2
3V
OUT2
3V
SENSE2
3V
GATE2
3.3V
OUT
PGOODn
5V/DIV
3.3V
3.3V
12V
PCIe
PLUG-IN
CONNECTOR CARD
3.3V
OUT
12V
OUT
4242 TA01a
U
Normal Power-Up Sequence
10ms/DIV
4242 F04
U
U
4242f
1
LTC4242
ABSOLUTE
AXI U RATI GS
Supply Voltages
V
CC
........................................................... –0.3V to 7V
12V
INn
.................................................... –0.3V to 20V
3V
INn
...................................................... –0.3V to 10V
AUXINn .................................................. –0.3V to 10V
Input Voltages
ONn, AUXONn, FONn ............................... –0.3V to 7V
ENn .......................................................... –0.3V to 7V
Output Voltages
FAULTn, PGOODn, AUXFAULTn,
AUXPGOODn ........................................... –0.3V to 7V
Analog Voltages
12V
SENSEn
.............................................. –0.3V to 20V
PACKAGE/ORDER I FOR ATIO
TOP VIEW
EN1
FON1
ON1
AUXON1
3V
OUT1
3V
GATE1
3V
SENSE1
3V
IN1
AUXIN1
1
2
3
4
5
6
7
8
9
36 FAULT1
35 AUXFAULT1
34 PGOOD1
33 12V
IN1
32 12V
SENSE1
31 12V
GATE1
30 12V
OUT1
29 AUXOUT1
28 GND
27 AUXOUT2
26 12V
OUT2
25 12V
GATE2
24 12V
SENSE2
23 12V
IN2
22 PGOOD2
21 AUXFAULT2
20 FAULT2
19 EN2
38 37 36 35 34 33 32
AUXON1 1
3V
OUT1
2
3V
GATE1
3
3V
SENSE1
4
3V
IN1
5
AUXIN1 6
V
CC
7
AUXIN2 8
3VIN2 9
3V
SENSE2
10
3V
GATE2
11
3V
OUT2
12
13 14 15 16 17 18 19
AUXFAULT2
AUXON2
FAULT2
PGOOD2
FON2
ON2
EN2
39
31 12V
IN1
30 12V
SENSE1
29 12V
GATE1
28 12V
OUT1
27 AUXOUT1
26 GND
25 AUXOUT2
24 12V
OUT2
23 12V
GATE2
22 12V
SENSE2
21 12V
IN2
20 AUXPGOOD2
V
CC
10
AUXIN2 11
3V
IN2
12
3V
SENSE2
13
3V
GATE2
14
3V
OUT2
15
AUXON2 16
ON2 17
FON2 18
G PACKAGE
36-LEAD PLASTIC SSOP
UHF PACKAGE
38-LEAD (5mm
×
7mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 95°C/W
T
JMAX
= 125°C,
θ
JA
= 34°C/W
EXPOSED PAD (PIN 39) IS GND, PCB ELECTRICAL CONNECTION OPTIONAL
ORDER PART NUMBER
LTC4242CG
LTC4242IG
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
ORDER PART NUMBER
LTC4242CUHF
LTC4242IUHF
UHF PART MARKING*
4242
4242
*The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges.
4242f
2
AUXPGOOD1
AUXFAULT1
PGOOD1
FAULT1
FON1
ON1
EN1
U
U
W
W W
U
W
(Note 1)
12V
GATEn
................................................ –0.3V to 25V
12V
OUTn
(Note 3) .. 12V
GATEn
– 5V to 12V
GATEn
+ 0.3V
AUXOUTn, 3V
SENSEn
.............................. –0.3V to 10V
3V
GATEn
.................................................. –0.3V to 14V
3V
OUTn
(Note 3) ....... 3V
GATEn
– 5V to 3V
GATEn
+ 0.3V
Operating Temperature Range
LTC4242C ................................................ 0°C to 70°C
LTC4242I ............................................. –40°C to 85°C
Storage Temperature Range
SSOP ................................................. –65°C to 150°C
QFN .................................................... –65°C to 125°C
stm32/stm8
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