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Power supply decoupling and filtering, Low voltage protection – Echelon LonWorks Router User Manual

Page 56

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Table 12. Series 5000 Router Current Requirements

Active

SysClk

Typical

Maximum

Receive Current

5 MHz

9 mA

15 mA

10 MHz

9 mA

15 mA

20 MHz

15 mA

23 mA

40 MHz

23 mA

33 mA

Transmit Current 5 – 40 MHz

Receive Current

+ 15 mA

Receive Current

+ 18 mA

The Series 5000 router chip requires a 3.3 V nominal power supply (3.0 V to 3.6 V

range). The current requirements assume no load on digital I/O pins, and that

the I/O lines are not switching. In addition, the current consumption in transmit

mode represents a peak value rather than a continuous usage value because a

Series 5000 router does not typically transmit data continuously.
Note that the stated current requirements do not include the requirements for

performing reads or writes to the external memory (the two-wire serial

EEPROM), which typically add 1 to 2 mA. When not in use, the EEPROM

typically requires only 2 μA.

Power Supply Decoupling and Filtering

The design for a L

ON

W

ORKS

router power supply must consider filtering and

decoupling requirements of the router. The power supply filter must prevent

noise generated by the router from conducting onto external wires, and in the

case of DC-DC switching power supplies, must prevent noise generated by the

supply from interfering with router operation. Switching power supply designs

must also consider the effects of radiated EMI.
An RTR-10 router or a Series 5000 half-router each requires a clean power supply

to prevent RF noise from conducting onto the network through active drive

circuits. Power supply noise near the network transmission frequency could

degrade network performance.
The RTR-10 router includes 2.2 μF and 0.1 μF power supply bypass capacitors

close to pins 10 and 31. In general, high-frequency decoupling capacitors valued

at 0. 1μF or 0.01 μF placed near pins 10 and 31 on the motherboard are

necessary to reduce EMI.
See the Series 5000 Chip Data Book for information about power-supply

decoupling and filtering for Series 5000 chips, including the Router 5000 and FT

Router 5000.

Low Voltage Protection

For a RTR-10 design, it is necessary to include a low voltage protection circuit on

the router motherboard to drive the RESET~ line of the RTR-10 router. See

Section 9.4 of the Neuron Chip Data Book. Failure to include such protection

may cause data corruption to configuration data maintained in EEPROM on the

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LONWORKS Router Electrical Interfaces