RF65 datasheet(66/72 Pages) ETC2

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Page 66

RF65

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ADVANCED COMMUNICATIONS & SENSING

DATASHEET

7. Application Information

7.1. Crystal Resonator Specification

Table 26 shows the crystal resonator specification for the crystal reference oscillator circuit of the RF65. This

specification covers the full range of operation of the RF65 and is employed in the reference design.

Table 26 Crystal Specification

Symbol

Description

Conditions

Min

Typ

Max

Unit

FXOSC

XTAL Frequency

MHz

XTAL Serial Resistance

140

ohms

XTAL Shunt Capacitance

2.8

CLOAD

External Foot Capacitance

On each pin XTA and XTB

Notes - the initial frequency tolerance, temperature stability and ageing performance should be chosen in accordance

with the target operating temperature range and the receiver bandwidth selected.

- the loading capacitance should be applied externally, and adapted to the actual Cload specification of the XTAL.

- A minimum XTAL frequency of 28 MHz is required to cover the 863-870 MHz band, 29 MHz for the 902-928 MHz

band

7.2. Reset of the Chip

A power-on reset of the RF65 is triggered at power up. Additionally, a manual reset can be issued by controlling pin 6.

7.2.1. POR

If the application requires the disconnection of VDD from the RF65, despite of the extremely low Sleep Mode current, the

user should wait for 10 ms from of the end of the POR cycle before commencing communications over the SPI bus. Pin 6

(Reset) should be left floating during the POR sequence.

VDD

Pin 6

(output)

Undefined

Wait for

10 ms

Chip is ready from

this point on

Figure 34. POR Timing Diagram

Please note that any CLKOUT activity can also be used to detect that the chip is ready.

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