19
ASC Breakout Board
Figure 14. 5 V Hot Swap Circuit
The Hot Swap circuit is designed to work with the Hot Swap component in the Platform Designer software. Platform
Designer will automatically generate the Hot Swap algorithm and device configuration based on user defined set-
tings for input voltage, MOSFET characteristics, load capacitance, and other parameters. For more detail on the
Hot Swap algorithm and working with Hot Swap in Platform Designer, see the References section.
The Hot Swap circuit can be broken into three sections in order to understand the operation of the overall circuit:
• Hot Swap
– Load-Based Using Standard MOSFET
– Supply-Based Using MOSFET with Sense Output
• Fast Shutdown Circuit
• Current Sensing Test Circuit
Load-Based Hot Swap (Standard MOSFET)
The circuit in Figure 15 illustrates the Load-based Hot Swap using Standard MOSFET. The Load-based Hot Swap
circuit has Q6 connected between the current sensing resistor R60 and the load capacitor. The N type MOSFET
Q6 is controlled by the high voltage output (HVOUT2) from the ASC. The gate resistor (R61) and gate-source
capacitor (C22) are used to maintain a soft turn on of Q6. The increased gate capacitance smooths out the current
during the hysteretic control stage (see the References section for more details on the Hot Swap behavior).
IMON
VMON6
HVOUT2
Population Options:
Standard MOSFET (Option A):
Q6, C22, R61,
R60, R58, R59
MOSFET w/ Sense (Option B):
Q5, R57, R55,
C23, R54, R56
sense X 600
ASC INT
Connector
Fast
Shutdown
VMON5
I_5V_HS - 1V per 1A sensed
Demonstration Circuit to Output
Monitored Current to Test Point
(Not required for Hot Swap Operation)
MOSFET w/ Sense (Option B)
+5
V
_HS
+3.3
V
5
V
_HS_DRI
V
E
Sheet [2]
+5
V
_HS
Sheet [2,4]
5
V
_HS_CURRE
N
T_P
Sheet [2]
5
V
_HS_CURRE
N
T_
N
Sheet [2]
ASC_5
V
_OC_SHUTDO
WN
Sheet [2]
+5
V
_S
W
Sheet [2,9,10]
kelvin
sense
Q5
BUK7C06-40AITE
R5
8
0
TP7
5
V
_I
N
1
R54
2.2k
R60
0.005
2
W
, 1%
TP17
I_5
V
_HS
1
TP16
5
V
_SD
N
1
R59
0
C22
100nF
R62
4.7k
R61
2.2k
R57
3.30
1%
R55
0
R64
1k
C23
100nF
D10
Red
SM_LED_0603
R94
20k
1%
TP12
5
V
_HS
1
Q6
IRF7
8
32
J6
2 Position Terminal Block
A
B
Q7
2
N
3904
R63
3.3k
R56
0
C13
6
8
0
u
F
10
V
U2
ZXCT1009
V
sense+
2
V
sense-
3
Io
u
t
1