DM505LRBABF datasheet(111/295 Pages) TI2

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vssa_osc1

Device

xo_osc1

xi_osc1

SPRS91v_CLK_06

111

DM505

www.ti.com

SPRS976E – NOVEMBER 2016 – REVISED MAY 2018

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Specifications

Table 5-20. OSC1 Crystal Electrical Characteristics (continued)

NAME

DESCRIPTION

MIN

TYP

MAX

UNIT

tj(xiosc0)

Frequency accuracy(1), xi_osc1

Ethernet not used

±200

ppm

Ethernet RGMII using

derived clock

±50

ppm

(1) Crystal characteristics should account for tolerance+stability+aging.

When selecting a crystal, the system design must take into account the temperature and aging

characteristics of a crystal versus the user environment and expected lifetime of the system.

Table 5-21 details the switching characteristics of the oscillator and the requirements of the input clock.

Table 5-21. Oscillator Switching Characteristics—Crystal Mode

NAME

DESCRIPTION

MIN

TYP

MAX

UNIT

Oscillation frequency

Range from 19.2 to 32

MHz

tsX

Start-up time

5.9.4.1.3.2 OSC1 Input Clock

A 1.8-V LVCMOS-Compatible Clock Input can be used instead of the internal oscillator to provide the

SYS_CLK2 clock input to the system. The external connections to support this are shown in, Figure 5-17.

The xi_osc1 pin is connected to the 1.8-V LVCMOS-Compatible clock sources. The xo_osc1 pin is left

unconnected. The vssa_osc1 pin is connected to board ground (VSS).

Figure 5-17. 1.8-V LVCMOS-Compatible Clock Input

Table 5-22 summarizes the OSC1 input clock electrical characteristics.

Table 5-22. OSC1 Input Clock Electrical Characteristics—Bypass Mode

NAME

DESCRIPTION

MIN

TYP

MAX

UNIT

Frequency

Range from 12 to 38.4

MHz

CIN

Input capacitance

2.819

3.019

3.219

IIN

Input current (3.3V mode)

µA

tsX

Start-up time(1)

See(2)

(1) To switch from bypass mode to crystal or from crystal mode to bypass mode, there is a waiting time about 100 μs; however, if the chip

comes from bypass mode to crystal mode the crystal will start-up after time mentioned in Table 5-21, tsX parameter.

(2) Before the processor boots up and the oscillator is set to bypass mode, there is a waiting time when the internal oscillator is in

application mode and receives a wave. The switching time in this case is about 100 μs.

Table 5-23 details the OSC1 input clock timing requirements.

DM505LRBABF Datasheet(PDF) 111 Page - Texas Instruments

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