17
ASC Breakout Board
Figure 13. Board Power Supply Circuit
The +12 V connects through schottky diode D16 to the +11.3 V rail, while the +5 V connects through schottky
diode D18 to the +11.3 V rail. Through this configuration, the +11.3 V rail will be sourced by either the +12V_SW
rail (if present) or the +5V_SW rail (if present and +12V_SW rail not present). The +11.3 V rail is connected to the
ASC Interface connector. This rail may be used as an input to a 12 V DC-DC converter on the main FPGA board.
The +11.3 V rail is also used as the input voltage to DCDC5. DCDC5 steps down the +11.3 V input to a +3.3 V out-
put voltage. The +11.3 V is buffered and filtered by C29 and C31. The +3.3 V output is buffered and filtered by C30
and C32. The +3.3 V output voltage is set by the 4.53 k
Ω
resistor (R96) connected to the DCDC5 Trim pin.
The header J14 is used to connect the DCDC5 output to the +3.3 V rail using a 2-pin jumper. Placing a jumper on
J14 will supply the ASC Breakout Board +3.3 V from DCDC5. It will also p3.3 V to the ASC Interface Con-
nector – this will power the FPGA main board from only the +12V_SW input on the ASC Breakout Board. No other
input supply is required.
5 V Hot Swap (Not Populated)
The ASC Breakout Board provides a set of footprints and connections for implementing a 5 V Hot Swap circuit
using the ASC’s built in hardware. Table 8 lists the components and signals associated with 5 V Hot Swap opera-
tion on the ASC Breakout Board.
Table 8. 5 V Hot Swap Components and Signals
Component / Signals
Ref. Des.
Schematic
Sheet
Description
Components Not Populated on Breakout Board
Current sense resistor
R60
2
6
5 m
Ω
2 W resistor for supply side current monitoring with
IMON1 input of ASC
IMON1 Isolation Resistor
R58
2
, R59
2
6
Zero
Ω
resistors – support population option for standard
MOSFET versus MOSFET with Sense output
MOSFET Switch
Q6
2
6
N-Channel MOSFET load-side Hot Swap switch supplies
power to +5V_HS and load capacitor C13.
Gate Drive Resistor
R61
2
6
2.2 k
Ω
resistor, located close to MOSFET Q6, limits parasitic
oscillations at the gate of Q6. Works with C22 to slow switching
at Q6, limiting current ripple during hysteretic switching.
Gate-Source Capacitor
C22
2
6
100 nF capacitor, works with R61 to slow switching at Q6, lim-
iting current ripple during hysteretic switching.
Populate jumper to provide
3.3V power from ASC Eval Board
3.3V
1A
12V to 4.8V input range
+11.3
V
+3.3
V
+12
V
+5
V
+11.3
V
+11.3
V
+3.3
V
Sheet [2,3,4,5,6,7,
8
,10]
+5
V
_S
W
Sheet [2,6,10]
+12
V
_S
W
Sheet [7,10]
+11.3
V
Sheet [2]
J14
HEADER 2
1
2
C31
100nF
25
V
S
W
1
S
W
DPDT
2
3
5
6
1
4
J1
2 Position Terminal Block
A
B
J2
P
W
R JACK
3
2
1
J3
2 Position Terminal Block
A
B
R96
4.53K
C30
22
u
F
25
V
D17
TRA
N
ZORB
C32
100nF
C29
22
u
F
25
V
N
QR002A0X4Z
DCDC5
G
N
D
3
V
in
2
On-Off Control
1
Trim
5
V
o
u
t
4
D16
N
SR0530P2T5G
D1
8
N
SR0530P2T5G
