AFS090 datasheet(38/334 Pages) MICROSEMI

38 / 334 page

Device Architecture

2- 22

R e visio n 2

Figure 2-18 • Crystal Oscillator: RC Time Constant Values vs. Frequency (typical)

Table 2-10 • XTLOSC Signals Descriptions

Signal Name

Width

Direction

Function

XTL_EN*

Enables the crystal. Active high.

XTL_MODE*

Settings for the crystal clock for different frequency.

Value

Modes

Frequency Range

b'00

RC network

32 KHz to 4 MHz

b'01

Low gain

32 to 200 KHz

b'10

Medium gain

0.20 to 2.0 MHz

b'11

High gain

2.0 to 20.0 MHz

SELMODE

Selects the source of XTL_MODE and also enables the

XTL_EN. Connect from RTCXTLSEL from AB.

For normal operation or sleep mode, XTL_EN

depends on FPGA_EN, XTL_MODE depends on

MODE

For

Standby

mode,

XTL_EN

enabled,

XTL_MODE depends on RTC_MODE

RTC_MODE[1:0]

Settings for the crystal clock for different frequency ranges.

XTL_MODE uses RTC_MODE when SELMODE is '1'.

MODE[1:0]

Settings for the crystal clock for different frequency ranges.

XTL_MODE uses MODE when SELMODE is '0'. In Standby,

MODE inputs will be 0's.

FPGA_EN*

0 when 1.5 V is not present for VCC 1 when 1.5 V is present

for VCC

XTL

Crystal Clock source

CLKOUT

OUT

Crystal Clock output

Note:

*Internal signal—does not exist in macro.

0.0

1.00E-0.7

1.00E-0.6

1.00E-0.5

1.00E-0.4

1.00E-0.3

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Frequency (MHz)

RC Time Constant Values vs. Frequency

AFS090 Datasheet(PDF) 38 Page - Microsemi Corporation

AFS090 Datasheet(HTML) 38 Page - Microsemi Corporation

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