LTC4240CGN#PBF Linear Technology, LTC4240CGN#PBF Datasheet - Page 25

• Manufacturer Part Number: LTC4240CGN#PBF
• Description: IC CTLR HOT SWAP CPCI I2C 28SSOP
• Manufacturer: Linear Technology
• Type: Hot-Swap Controllerr

Specifications of LTC4240CGN#PBF

• Applications: CompactPCI™
• Internal Switch(s): No
• Voltage - Supply: 3.3V, 5V, ±12V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP (0.150", 3.95mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIO S I FOR ATIO
Disallowing bulk capacitors on the input power pins
mitigates the inrush current during hot plug. However, it
also tends to create a resonant circuit formed by the
inductance of the backplane power supply trace and the
parasitic capacitance of the plug-in board (mainly due to
the large power FET). Upon board insertion, the ringing of
this circuit will exhibit peak overshoot as high as 2.5 times
the steady state voltage (>30V for 12V).
There are two methods for abating the effects of these high
voltage transients: using zener clamps, and using snubber
U
MEDIUM 5V
MEDIUM 3.3V
MEDIUM 5V
LONG 3.3V
LONG
LONG 5V
U
GND
5V
CONNECTOR
CompactPCI
BACKPLANE
D1, D2: BAV99
(MALE)
R22, 2.74
R21, 1.74
Z3, Z4: 1PMT5.0AT3
*ADDITIONAL DETAILS OMITTED FOR CLARITY
Figure 17. Place Transient Protection Device Close to the LTC4240
0.1 F
Z3
2.7
C7
R23
W
CONNECTOR
CompactPCI
BACKPLANE
*ADDITIONAL DETAILS OMITTED FOR CLARITY
(FEMALE)
Figure 15. 5V Supply Only Application Circuit
BD_SEL#
Figure 16. BD_SEL# Pushbutton Toggle Switch
Z4: 1PMT5.0AT3
3V
GND
IN
22
2.74
CONNECTOR
CompactPCI
BACKPLANE
R22
0.005
(MALE)
R1
3V
5V
U
SENSE
IN
23
CONNECTOR
BACKPLANE
CompactPCI
Z4
(FEMALE)
Si7880DP
10
GATE
Q1
3V
GND
19
R3
10
IN
22
D1
D2
3V
LTC4240*
PUSHBUTTON
3V
OUT
24
GND
SENSE
SWITICH
23
100
10
5V
networks. Snubbers are RC networks whose time
constants are large enough to damp the inductance of the
parasitic resonant circuit. The snubber capacitor should
be 10X to 100X the value of the plug-in board parasitic
capacitance. The value of the series snubber resistor
should be large enough to damp the resulting
R-L-C circuit and is typically between 1 and 50 . These
protection networks should be mounted very close to the
LTC4240 in order to minimize parasitic inductance. This is
shown in Figure 17 for the 3.3V and 5V supplies.
IN
*ADDITIONAL DETAILS OMITTED FOR CLARITY
0.007
21
R2
5V
IN
21
5V
0.007
V(I/O)
LTC4240*
SENSE
R2
5V
20
1.2k
Si7880DP
SENSE
1k
20
Q2
28
10
Si7880DP
R4
10
5V
GATE
OFF/ON
GND
Q2
LTC4240*
OUT
19
6
R4
10
4240 F16
R5
1k
5V
OUT
6
R5
1k
0.047 F
2.7
3V
C1
0.1 F
0.047 F
Z4
1644 F17
OUT
C1
24
4240 F15
5V
AT 5A
3V
AT 7.6A
OUT
OUT
C
L(5VOUT)
5V
OUT
LTC4240
25
4240f