Vcc5_sby routing, Power state and reset signal routing – Kontron COMe Starterkit Eval T2 User Manual

Page 168

Power and Reset

Table 56:

Approximate Copper Trace Current Capability per IPC-2221 Charts

Trace Type

Max Current with
10°C Temp Rise

Max Current with
20°C Temp Rise

100 mil wide internal trace ½ ounce/ 17μm base copper

1.3 A

1.8 A

200 mil wide internal trace ½ ounce/ 17μm base copper

2.0 A

3.0 A

400 mil wide internal trace ½ ounce/ 17μm base copper

3.5 A

5.0 A

100 mil wide internal trace 1 ounce/ 35μm base copper

2.1 A

3.0 A

200 mil wide internal trace 1 ounce/ 35μm base copper

3.5 A

5.2 A

400 mil wide internal trace 1 ounce/ 35μm base copper

6.0 A

8.0 A

100 mil wide external trace ½ ounce/ 17μm base copper

2.4 A

3.4 A

200 mil wide external trace ½ ounce/ 17μm base copper

4.0 A

5.5 A

400 mil wide external trace ½ ounce/ 17μm base copper

7.0 A

10.0 A

3.5.3.

VCC5_SBY Routing

The +5V Suspend power rail, if used, should be sized to handle 2A. Most, but not all, Modules
will use considerably less than 2A for this power rail. Modules with multiple Ethernet channels
and wake-on-LAN capability will use more current. The COM Express Specification allows up to
2A on this rail.

3.5.4.

Power State and Reset Signal Routing

Power state and reset signals are single-ended signals that do not have any particular routing
constraints.
To utilize the full functionality of PCI Express devices on the COM Express Carrier Board, some
additional supply voltages are necessary besides the standard supply voltages of the ATX power
supply. Many PCI Express devices are capable of generating wake up events during Suspend
operation; for example an external PCI Express Ethernet device that supports 'Wake On LAN'
functionality. Therefore, it is necessary to generate an additional 3.3V Suspend voltage on the
Carrier Board to supply such devices during Suspend operation. The voltage regulator must be
designed to meet the power requirements of the connected devices.

The PCI Express specification defines maximum power requirements for the different PCI
Express connectors and/or devices. The power supply for the Carrier Board must be designed to
meet these maximum power requirements. Table 57 below shows the maximum current
consumption defined for the different types of PCI Express connectors.

Table 57:

PCIe Connector Power and Bulk Decoupling Requirements

Power Rail

PCIe x1, x4 or x8
Connector

PCIe x16
Connector

ExpressCard
Connector

PCIe Mini Card
Connector

VCC_12V

2.1A @ 1000uF bulk

5.5A @ 2000uF bulk

VCC_3V3

3.0A @ 1000uF bulk

1.35A

VCC_3V3_SB

375mA @ 150uF bulk

275mA

2.75A

VCC_1V5

750mA

500mA

PICMG

COM Express

Carrier Board Design Guide

Rev. 2.0 / December 6, 2013

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