1
DEMO MANUAL DC116
HOT SWAP CONTROLLER
LTC1421 Hot Swap Controller
Controls Three Supplies
Demonstration circuit DC116 is a protected, triple-output
Hot Swap
TM
controller. This circuit is designed to allow a
PC board to be safely inserted into and removed from a live
backplane without disturbing the system power or damag-
ing the connector pins due to high inrush currents. A
programmable electronic circuit breaker protects against
shorts.
Also included on the demo board are LEDs that indicate
whether the circuit breaker has tripped, a power failure has
occurred or the switches are turned off. A push-button
switch is provided for users to generate a system reset and
cycle the outputs. Dip switches allow the trip levels of the
output voltage monitoring circuitry to be changed.
The complete demo includes two separate boards,
DC116A and DC116B. The DC116B is used to simulate the
system backplane with three supply inputs. All the inputs
are bypassed with large capacitors. The DC116A is the
daughter board to be inserted into and removed from the
system power bus. The LTC
®
1421 and all other compo-
nents are placed on this board. A staggered-pin connector
is used to ensure proper connection sequencing.
The applications for DC116 include any system with a data
bus and multiple power supplies that needs to be inserted
into or removed from a live system backplane.
DESCRIPTIO
U
DC116B
System Backplane
DC116A
Hot Swap Controller
BOARD PHOTOS
, LTC and LT are registered trademarks of Linear Technology Corporation.
Hot Swap is a trademark of Linear Technology Corporation.
DC116A PHOTO DC116B PHOTO
2
DEMO MANUAL DC116
HOT SWAP CONTROLLER
SYMBOL PARAMETER CONDITIONS VALUE
V
CC
, V
DD
Input Supply Voltage Positive Supply 3V to 12.6V
V
EE
Input Supply Voltage Negative Supply –3V to –12.6V
I
LIM
Maximum Output Current V
CC2
10A
V
DD2
2A
PERFOR A CE SU ARY
UWWW
TYPICAL PERFORMANCE CHARACTERISTICS
UW
0V
5V/DIV
V
DD2
V
CC2
V
EE2
Figure 1. Live Insertion into the System Backplane
dc116 TPC01
Figure 2. Live Removal from the System Backplane
dc116 TPC01
0V
5V/DIV
V
DD2
V
EE2
V
CC2
PACKAGE DIAGRA
W
LTC1421CSW
1
2
3
4
5
6
7
8
9
10
11
12
TOP VIEW
SW PACKAGE
24-LEAD PLASTIC SO WIDE
24
23
22
21
20
19
18
17
16
15
14
13
CON1
CON2
POR
FAULT
DISABLE
PWRGD
RESET
REF
CPON
RAMP
FB
GND
AUXV
CC
V
CCLO
SETLO
GATELO
V
OUTLO
V
CCHI
SETHI
GATEHI
V
OUTHI
COMPOUT
COMP
–
COMP
+
3
DEMO MANUAL DC116
HOT SWAP CONTROLLER
SCHE ATIC DIAGRA
WW
DC116A
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
J101
A1 B1
B2
B3
B4
B5
B6
B7
B8
C1
C2
C3
C4
C5
C6
C7
C8
A2
A3
A4
A5
A6
A7
A8
AA1
AA2
AA3
AA4
AA5
AA6
AA7
AA8
MILLIPACS
HM1G41FBR000H6
BOLD LINES INDICATE
HIGH CURRENT PATHS
VCC1
VDD1
VEE1
VEE2
VDD2
VDD2
VCC2
VCC2 VDD2 VEE2
R1
0.005Ω
SETLO
GATELO
OUTLO
TP3
SETHI
C7
0.1µF
C1
0.1µF
C2
0.047µF
TP12
TP8
TP16
TP15
S2
RESET
RESET
TP1
VCC1
TP9
TP10
TP11
RESET
COMPOUT
REF
TP14
DC116 SDa
R22
7.5k
1%
TP7
TP6
TP5
+
+
R21
20k
1%
R6
10k
5% R7
19.6k
1%
R9
20k
1%
R10
7.15k
1%
R8
2.55k
1%
R11
205k
1%
R19
470Ω
R12
23.2k
1%
C9, 0.1µF
+
R18
470Ω
R20
470Ω
R4
20k
R14
1.5k C6
0.1µF
R3
0.025ΩR23
0Ω
R5
16k
Q2
Si4410DY
SILICONIX
Q3
Si4410DY
SILICONIX
Q1
MTB50N06E
R16
1.5k
R17
1.5k
R15
1.5k
C4
1000µF
25V
C5
2200µF
16V
C3
1000µF
25V
R13, 470Ω
D6
RED
D8
AMBER
D1
RED TP13
TP2
TP4
D4
RED
D2
RED
D3
GRN
D7
GRN
COMP–
COMP+
D5
GRN
U1
LTC1421CSW
24
23
22
21
20
19
18
17
16
15
14
13
1
2
3
4
5
6
7
8
9
10
11
12
CON1
CON2
POR
FAULT
DISABLE
PWRGD
RESET
REF
CPON
RAMP
FB
GND
AUXVCC
VCCLO
SETLO
GATELO
VOUTLO
VCCHI
SETHI
GATEHI
VOUTHI
COMPOUT
COMP–
COMP+
S1
S8
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
C8
1µF
4
DEMO MANUAL DC116
HOT SWAP CONTROLLER
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
58
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
TP6
GROUND P101
A1 B1
B2
B3
B4
B5
B6
B7
B8
C1
C2
C3
C4
C5
C6
C7
C8
A2
A3
A4
A5
A6
A7
A8
AA1
AA2
AA3
AA4
AA5
AA6
AA7
AA8
MILLIPACS
HM1V41HPR000H6
BOLD LINES INDICATE
HIGH CURRENT PATHS
VEE
VCC
VDD
TP7
TP8
TP2
TP4
DATA
AUX TP5
TP10
DISABLE
FAULT
POR
DC116bSDb
R1
10k
TP9
C1
470µF
25V
VCC
+
C2
470µF
25V
+
TP3 R2
10k
VCC TP1
SCHE ATIC DIAGRA
WW
DC116B
5
DEMO MANUAL DC116
HOT SWAP CONTROLLER
PARTS LIST
DC116A
REFERENCE
DESIGNATOR QUANTITY PART NUMBER DESCRIPTION VENDOR TELEPHONE
C1, C6, C7, C9 4 12065C104KAT2 0.1µF 50V 10% X7R Capacitor AVX (803) 946-0362
C2 1 12065C473KAT2 0.047µF 50V 10% X7R Capacitor AVX (803) 946-0362
C3, C4 2 25MV102CZ 1000µF 25V Aluminum Capacitor Sanyo (619) 661-6835
C5 1 16MV222CZ 2200µF 16V Aluminum Capacitor Sanyo (619) 661-6835
C8 1 6Y5U105Z025AL 1µF 25V 10% Y5U Capacitor Murata (814) 237-1431
D1, D2, D4, D6 4 5600F1 Red LED Chicago Miniature Lamp (201) 489-8989
D3, D5, D7 3 5600F5 Green LED Chicago Miniature Lamp (201) 489-8989
D8 1 5600F7 Yellow LED Chicago Miniature Lamp (201) 489-8989
J101 1 HM1G41FBR000H6 Millipacs Female Connector FCI (717) 767-8005
Q1 1 MTB50N06E N-Channel MOSFET, 50A, 60V Motorola (602) 244-3576
Q2, Q3 1 Si4410DY N-Channel MOSFET Siliconix (800) 554-5565
R1 1 WSL-2010-005-1% 0.005Ω 1/2W 1% Resistor Dale (605) 665-9301
R3 1 WSL-2010-025-1% 0.025Ω 1/2W 1% Resistor Dale (605) 665-9301
R4 1 CR32-203J-T 20k 1/8W 5% Resistor AVX (803) 946-0524
R5 1 CR32-163J-T 16k 1/8W 5% Resistor AVX (803) 946-0524
R6 1 CR32-103J-T 10k 1/8W 5% Resistor AVX (803) 946-0524
R7 1 CR32-1962F-T 19.6k 1/8W 1% Resistor AVX (803) 946-0524
R8 1 CR32-2491F-T 2.49k 1/8W 1% Resistor AVX (803) 946-0524
R9, R21 2 CR32-2002F-T 20k 1/8W 1% Resistor AVX (803) 946-0524
R10 1 CR32-7151F-T 7.15k 1/8W 1% Resistor AVX (803) 946-0524
R11 1 CR32-2053F-T 205k 1/8W 1% Resistor AVX (803) 946-0524
R12 1 CR32-2322F-T 23.2k 1/8W 1% Resistor AVX (803) 946-0524
R13, R18 to R20 4 CR32-470J-T 470Ω 1/8W 5% Resistor AVX (803) 946-0524
R14 to R17 4 CR32-152J-T 1.5k 1/8W 5% Resistor AVX (803) 946-0524
R22 1 CR32-7501F-T 7.5k 1/8W 1% Resistor AVX (803) 946-0524
R23 1 CJ-000T 0Ω 1/8W 5% 1206 Resistor AVX (803) 946-0524
S1 1 DMR-08 Switch APEM (781) 246-1007
S2 1 MJTP1236 Switch APEM (781) 246-1007
TP1, TP4 to TP7, TP9 to 12 1502-2 Turret Keystone (718) 956-8900
TP11, TP13 to TP16
TP2, TP3, TP8, TP12 4 575-4 Banana Jack Keystone (718) 956-8900
U1 1 LTC1421CSW IC Linear Technology (408) 432-1900
1 Demo Board DC116A Printed Circuit Board
DC116B
C1, C2 2 25MV470CZ 470µF 25V Elect Capacitor Sanyo (619) 661-6835
P101 1 HM1V41HPR000H6 Millipacs Male Connector FCI (717) 767-8005
R1, R2, R3 2 CR32-103J-T 10k 1/8W 5% Resistor AVX (803) 946-0524
TP1 to TP5, TP10 6 1502-2 Turret Keystone (718) 956-8900
TP6 to TP9 4 575-4 Banana Jack Keystone (718) 956-8900
4 #4-40x1/4” Screw HWD Any
4 #4-40x1/2” Stand-Off Nylon Hex HWD Keystone (718) 956-8900
1 Demo Board DC116B Printed Circuit Board
6
DEMO MANUAL DC116
HOT SWAP CONTROLLER
The demonstration board set, DC116, is easily set up for
evaluation of the LTC1421 IC. Please follow the proce-
dure outlined below for error-free operation.
• Connect the positive power supply with the lower
potential to V
CC
(TP9) and the higher one to V
DD
(TP8)
on DC116B. Connect the ground lead(s) to TP6. Do
not exceed 12.6V for either supply to ensure proper
operation of the LTC1421.
• Connect the negative power supply to V
EE
(TP7)
and GND (TP6) on DC116B. Do not exceed –12.6V
on V
EE
.
QUICK START GUIDE
• Connect the loads to outputs V
CC2
(TP8), V
DD2
(TP3)
and V
EE2
(TP2) on the DC116A board. Connect the
return side of the lead(s) to TP12 or TP16 (GND).
• Select the proper dip switches to monitor the outputs
and set the trip level for the RESET output.
• Apply power and insert the daughter board (DC116A)
into the system backplane (DC116B). Rock the daugh-
ter board back and forth to ensure good connection.
• The LEDs will turn on to indicate the status of the input
and output supplies as well as the circuit breaker.
OPERATIO
U
The circuit shown in the Schematic Diagram allows three
power supplies, V
DD
, V
CC
and V
EE
, to be safely inserted
into and removed from the backplane. V
CC
and V
DD
are
both positive supplies, whereas V
EE
is a negative supply.
The main supply to the LTC1421 is from V
CC
; its voltage
should be less than or equal to that of V
DD
. The nominal
voltages are 5V for V
CC
, 12V for V
DD
and –12V for V
EE
.
A 0.005Ω sense resistor (R1) sets the current limit to 10A
at the V
CC
output; R3 (0.025Ω) sets the current limit at V
DD
to 2A. The LTC1421 monitors the voltage across the sense
resistors. When either voltage is greater than 50mV, the
internal charge pump is turned off immediately and both
the gates and voltage outputs are actively pulled to ground.
The circuit breaker function remains active until the push-
button switch (S2) is pressed and released or the power is
cycled.
The LTC1421 limits the inrush current through the
N-channel pass transistor by increasing the voltage on the
gate in a controlled manner. The transient surge current
(I = C
OUT
• dV
OUT
/dt) drawn from the main backplane
power supply can then be limited to a safe value. The ramp
slope is determined by a fixed internal current source
(20µA) and a ramp capacitor (C9) connected between the
RAMP and GATEHI pins. The voltage at GATEHI rises with
a slope equal to 20µA/C
RAMP
. The voltage at the GATELO
pin is clamped one Schottky diode drop below GATEHI.
The negative supply voltage can be controlled using the
CPON pin. When the board makes a connection, the
N-channel pass transistor, Q2, is turned off by R4. CPON
is also pulled down to V
EE1
. When the charge pump is
turned on, CPON is pulled to V
CC1
and the gate of Q2 ramps
up with a time constant determined by R4, R5 and C2.
When the charge pump is turned off, CPON goes into high
impedance state; the gate of Q2 is then discharged to V
EE1
with a time constant determined by R4 and C2 and then Q2
turns off. There is no circuit breaker or current-limit
feature on the negative supply.
Power N-Channel MOSFET
External N-channel pass transistors are used to route the
power from the system power supply to the plug-in board.
An MTB50N06E from Motorola is used for the V
CC
output
and two 8-lead, surface mounted NFETs from Siliconix
(Si4410DY) are used for V
DD
and V
EE
. A number of similar
N-channel MOSFETs, available from different manufactur-
ers, are also well-suited for this type of application. As a
general rule, select the MOSFET with the lowest R
DS(ON)
to
get the smallest voltage drop across it at the maximum
output load.
7
DEMO MANUAL DC116
HOT SWAP CONTROLLER
OPERATIO
U
1. Close S3, S5 and S8: monitor V
DD2
at 10.8V; reset V
CC2
at 4.65V.
2. Close S1, S3, S6 and S8: monitor V
CC2
at 4.65V; reset
V
CC2
at 2.9V.
3. Close S4, S5 and S8: reset V
DD2
at 10.8V; reset V
CC2
at
4.65V.
4. Close S2, S3, S4 and S8: reset V
CC2
at 4.5V.
5. Close S3 and S7: monitor V
EE2
at –10.8V; reset V
CC2
at
4.65V.
Connector
A staggered-pin connector (HM1V41HPR000H6) from
FCI is used on the boards for hot swapping. The ground
pins are the longest, making connection first and breaking
connection last. This will prevent ESD damage on the rest
of the pins when a huge ground potential difference exists
between the two boards. The connect pins (CON1 and
CON2) are shortest, and are placed on the opposite end of
the connector. The LTC1421 will not start turning on the
pass transistors until the whole connector is plugged in
and both CON1 and CON2 are connected.
PCB LAYOUT A D FIL
UW
DC116A
Silkscreen Top
DC116A ASY
Assembly Top
LEDs
Several LEDs are included on the demo board to indicate
the status of the input and output voltages and the circuit
breaker. D2, D4 and D6, when turned on, indicate that the
input supplies (V
DD1
, V
EE1
and V
CC1
) from the connector
are ready. The green LEDs (D3, D5 and D7), when turned
on, indicate that the pass transistors are on and the input
supplies have been routed to the outputs. D8 is connected
from the RESET pin to V
CC1
through a 470Ω resistor. D8
turns on immediately after the board is inserted into the
system power supplies and turns off 200ms after the
PWRGD pin goes high. When the red LED (D1) lights up,
a general fault condition has occurred: either the circuit
breaker has tripped, a power failure has occurred or the
gate driver is turned off.
Dip Switches (S1 to S8)
Eight dip switches on the demo board provide users with
a convenient way to configure the output voltage(s) to be
monitored and the trip levels for the RESET output. Five
different configurations are listed below:
DC116A SLK
11
DEMO MANUAL DC116
HOT SWAP CONTROLLER
PC FAB DRAWI G
U
DC116A
D
G
G
G
G
G
G
C
BB B B B B BBBB
H
H
H
B B
C
C
C
A A A A
D
D
D
D
D
D
D
E
E
F
F
F
F
F
F
F
H
H
H
H
H
H
H
H
H
H
HH
H
H
H
H
G
G
2.600
3.975
NUMBER
SYMBOL DIAMETER OF HOLES PLATED
A 0.205 4 YES
B 0.094 12 YES
C 0.081 4 NO
D 0.060 8 NO
E 0.045 2 YES
F 0.035 18 YES
G 0.025 102 YES
H 0.015 39 YES
TOTAL HOLES 189
NOTES: UNLESS OTHERWISE SPECIFIED
1. MATERIAL: 2 LAYERS, 0.062" THICK FR-4 GLASS EPOXY 2 OZ COPPER CLAD
2. ALL DIMENSIONS ARE IN INCHES ±0.003
3. PLATE THRU HOLES WITH COPPER 0.0014 MIN THICKNESS.
ALL HOLE SIZES IN HOLE TABLE ARE AFTER PLATING
4. SILSCREEN: WITH WHITE EPOXY NONCONDUCTIVE INK
5. FINISH: SMOBC
6. SOLDER MASK: LPI, GREEN
DC116A FAB
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.
12
DEMO MANUAL DC116
HOT SWAP CONTROLLER
dc116 LT/TP 0898 500 • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1998
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507
●
www.linear-tech.com
PC FAB DRAWI G
U
DC116B
B
B B
B
AC
D
E
E
F
F
A
A
A
C
C
C
C
C
D
D
D
D
D
D
2.400
0.200
0.200
3.500
3.300
NUMBER
SYMBOL DIAMETER OF HOLES PLATED
A 0.205 4 YES
B 0.125 4 YES
C 0.094 6 YES
D 0.060 8 NO
E 0.030 96 YES
F 0.025 4 YES
TOTAL HOLES 122
NOTES: UNLESS OTHERWISE SPECIFIED
1. MATERIAL: 2 LAYERS, 0.062" THICK FR-4 GLASS EPOXY 2 OZ COPPER CLAD
2. ALL DIMENSIONS ARE IN INCHES ±0.003
3. PLATE THRU HOLES WITH COPPER 0.0014 MIN THICKNESS.
ALL HOLE SIZES IN HOLE TABLE ARE AFTER PLATING
4. SILSCREEN: WITH WHITE EPOXY NONCONDUCTIVE INK
5. FINISH: SMOBC
6. SOLDER MASK: LPI, GREEN
DC116B FAB
/
