1894KI-40LF IDT, 1894KI-40LF Datasheet - Page 14
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1894KI-40LF
Manufacturer Part Number
1894KI-40LF
Description
Ethernet ICs 3.3V 10/100 PHY RMII
Manufacturer
IDT
Datasheet
1.1894KI-40LFT.pdf
(53 pages)
Specifications of 1894KI-40LF
Rohs
yes
Part # Aliases
ICS1894KI-40LF
If a crystal is used as the clocking source, connect it to both
the REF_IN (pin 37) and REF_OUT (pin 36) pins of the
ICS1894-40. A pair of bypass capacitors on either side of
the crystal are connected to ground. The crystal is used in
the parallel resonance or anti-resonance mode. The value
of the load caps serve to adjust the final frequency of the
crystal oscillation. Typical applications would use 25 pF load
caps. The exact value will be affected by the board routing
capacitance on REF_IN and REF_OUT pins. Smaller load
capacitors raise the frequency of oscillation.
25 MHz Crystal Specification Table
25 MHz Oscillator Specification table
50 MHz Oscillator Specification table
Status Interface
The ICS1894-40 has five multi-function configuration pins
that report the PHY status by providing signals that are
intended for driving LEDs. Configuration is set by Bank0
Register 20.
IDT® 10BASE-T/100BASE-TX INTEGRATED PHYCEIVER WITH RMII INTERFACE
Specifications
Fundamental Frequency
Freq. Tolerance
Input Capacitance
Specifications
Output Frequency
Freq. Stability (including aging)
Duty cycle CMOS level one-half VDD
VIH
VIL
Specifications
Output Frequency
Freq. Stability (including aging)
Duty cycle CMOS level one-half VDD
VIH
VIL
ICS1894-40
10BASE-T/100BASE-TX INTEGRATED PHYCEIVER WITH RMII INTERFACE
Symbol Minimum
F0
Δ
Cin
Symbol Minimum
F0
Δ
Tw/T
Symbol Minimum
F0
Δ
Tw/T
F/f
F/f
F/f
24.99875 25.00000
24.99875 25.00000
49.9975 50.00000
2.79
2.79
Once the exact value of load capacitance is established it
will be the same for all boards using the same specification
crystal. The best way to measure the crystal frequency is to
measure the frequency of TXCLK (pin 28) using a frequency
counter with a 1 second gate time. Using the buffered output
TXCLK prevents the crystal frequency from being affected
by the measurement. The crystal specification is shown in
the 25MHz Crystal Specification table.
35
35
Typical Maximum
Typical Maximum
Typical Maximum
14
3
25.00125
25.00125
50.0025
±
±
0.33
±
0.33
50
50
65
50
65
MHz
Volts
Volts
Volts
Volts
ppm
Unit
MHz
MHz
Unit
ppm
Unit
ppm
pF
%
%
ICS1894-40
PHYCEIVER
REV K 022412