AC Timing Diagrams (Continued)

Applications Information

The DS90C383 and DS90CF384 are backward compatible

with the existing 5V FPD Link transmitter/receiver pair

(DS90CR583, DS90CR584, DS90CF583 and DS90CF584).

To upgrade from a 5V to a 3.3V system the following must be

addressed:

1.

Change 5V power supply to 3.3V. Provide this supply to

the V

CC, LVDS VCC and PLL VCC of both the transmitter

and receiver devices. This change may enable the re-

moval of a 5V supply from the system, and power may

be supplied from an existing 3V power source.

2.

The DS90C383 (transmitter) incorporates a rise/fall

strobe select pin. This select function is on pin 17,

formerly a V

CC connection on the 5V products. When the

rise/fall strobe select pin is connected to V

CC, the part is

configured with a rising edge strobe. In a system cur-

rently using a 5V rising edge strobe transmitter

(DS90CR583), no layout changes are required to ac-

commodate the new rise/fall select pin on the 3.3V

transmitter. The V

CC signal may remain at pin 17, and

the device will be configured with a rising edge strobe.

When converting from a 5V falling edge transmitter

(DS90CF583) to the 3V transmitter a minimal board

layout change is necessary. The 3.3V transmitter will

not be configured with a falling edge strobe if V

CC re-

mains connected to the select pin. To guarantee the

3.3V transmitter functions with a falling edge strobe pin

17 should be connected to ground OR left unconnected.

When not connected (left open) and internal pull-down

resistor ties pin 17 to ground, thus configuring the trans-

mitter with a falling edge strobe.

3.

The DS90C383 transmitter input and control inputs ac-

cept 3.3V TTL/CMOS levels. They are not 5V tolerant.

DS012887-21

C — Setup and Hold Time (Internal data sampling window) defined by Rspos (receiver input strobe position) min and max

Tppos — Transmitter output pulse position (min and max)

RSKM = Cable Skew (type, length) + Source Clock Jitter (cycle to cycle) (Note 10) + ISI (Inter-symbol interference) (Note 11)

Cable Skew — typically 10 ps–40 ps per foot, media dependent

Note 10: Cycle-to-cycle jitter is less than 250 ps at 65 MHZ

Note 11: ISI is dependent on interconnect length; may be zero

FIGURE 19. Receiver LVDS Input Skew Margin

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