Decoupling Scheme for UT200SpW4RTR (6/11)

Aeroflex Colorado Springs Application Note
AN-SPW-006-001
Decoupling techniques for the UT200SpW4RTR
Table 1: Cross Reference of Applicable Products
Manufacturer Part
SMD #
Device
Number
Type
200 Mbps 4-port SpaceWire router
UT200SpW4RTR
5962-08244
01
Product Name:
Internal PIC
WD41
1.0 Overview
The purpose of this application note is to review recommended decoupling techniques for the
UT200SpW4RTR SpaceWire router. With all the possible system variations such as power
supply voltage, temperature, operating frequency, and other configuration variations the system
designer is cautioned to perform a thorough analysis to verify the decoupling scheme works for
system specific requirements.
Information contained in this application note is a recommended decoupling scheme for the
UT200SpW4RTR. The decoupling scheme discussed below has been shown to work over the
temperature range of -40°C to +105°C, during compliance testing (ECSS-E-ST-50-12C), general
use of the device, and power supply variations I/O supply: VDD = 3.3V± 0.3V, Core supply:
VDDC = 2.5V ± 0.2V.
2.0 Capacitor Selection
As a rule of thumb for every five power supply pins a 0.01µF and a 0.1µF pair should be used to
properly decouple the UT200SpW4RTR device. Tantalum capacitors in the range of 47µF are
recommended.
There are 19 VDDC (2.5V) pins and 27 VDD (3.3V) pins on the 4-port SpaceWire Router device.
Table 2 details the power and ground connections for the WD41. VDDC should have
approximately four 0.01µF and a 0.1µF pairs and at least one 47µF. VDD should have
approximately six 0.01µF and a 0.1µF pairs and at least one 47µF. This termination scheme is a
recommended scheme; the system designer should perform the proper calculations to ensure that
this termination scheme meets specific system requirements.
Table 2. Power and ground connections for WD41
Description
Pin Name Pin Number
VDD
VDDC
T11, T5, N8, P11, N9, P14, N13, M7, K15, M10, J4, I/O and LVDS supply voltage, 3.3V
K3, J13, G3, H4, E7, H13, E10, G13, C11, G15, C14,
D8, A5, D9, D13, A11
T8, R1, P8, N4, M15, L6, L11, K5, K12, H1, G5, G12,
Core supply voltage, 2.5V
F6, F11, E15, D4, C8, B1, A8
Creation Date: June 21, 2011
Page 1 of 2
Modification Date:
VSS
T1, N14, T14, L5, R8, L13, R11, L15, P3, J15, M1, I/O and Core supply ground, 0.0V
H15, M5, F5, M8, F13, M9, F15, M12, D14, L7, L8,
L9, L10, K6, K7, K8, K9, K10, K11,J1, J5, J6, J7, J8,
J9, J10, J11, J12, H5, H6, H7, H8, H9, H10, H11,
H12, G6, G7, G8, G9, G10, G11, F7, F8, F9, F10, E1,
E5, E8, E9, E12, C3, B8, B11, A2, A14, R7, P5, P6,
P7, P9, P10, N5, N6, N7, N10, N11, N12, M4, M6,
M11, L4, K4, H2, G4, F4
3.0 UT200SpW4RTR-EVB Example Decoupling Scheme
Figure 1 shows the decoupling scheme used for the UT200SpW4RTR on the
UT200SpW4RTR-EVB Evaluation board. This decoupling scheme has been proven at
200Mbps, as well as 10Mbps operation, at temperature and voltage extremes.
VDD = 3.3V
47µF
+
0.01µF
0.1µF
0.01µF
0.1µF
0.01µF
0.1µF
VDDC = 2.5V
0.01µF
0.1µF
0.01µF
0.1µF
0.01µF
0.1µF
0.01µF
0.1µF
0.01µF
0.1µF
0.01µF
0.1µF
47µF
Figure 1. Example Decoupling Scheme
4.0 Summary
Selecting the proper decoupling capacitors for the UT200SpW4RTR device prevents power
supply droop during times when the router draws increased current. This application note is
intended to provide the system designer with a recommended decoupling scheme from which to
start designing from.
Creation Date: June 21, 2011
Page 2 of 2
Modification Date:
+
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