DS90CR215 Datasheet, PDF (1/17 Pages) National Semiconductor (TI) – +3.3V Rising Edge Data Strobe LVDS 21-Bit Channel Link - 66 MHz

August 2005
DS90CR215/DS90CR216
+3.3V Rising Edge Data Strobe LVDS 21-Bit Channel
Link - 66 MHz
General Description
The DS90CR215 transmitter converts 21 bits of CMOS/TTL
data into three LVDS (Low Voltage Differential Signaling)
data streams. A phase-locked transmit clock is transmitted in
parallel with the data streams over a fourth LVDS link. Every
cycle of the transmit clock 21 bits of input data are sampled
and transmitted. The DS90CR216 receiver converts the
LVDS data streams back into 21 bits of CMOS/TTL data. At
a transmit clock frequency of 66 MHz, 21 bits of TTL data are
transmitted at a rate of 462 Mbps per LVDS data channel.
Using a 66 MHz clock, the data throughput is 1.386 Gbit/s
(173 Mbytes/s).
The multiplexing of the data lines provides a substantial
cable reduction. Long distance parallel single-ended buses
typically require a ground wire per active signal (and have
very limited noise rejection capability). Thus, for a 21-bit wide
data and one clock, up to 44 conductors are required. With
the Channel Link chipset as few as 9 conductors (3 data
pairs, 1 clock pair and a minimum of one ground) are
needed. This provides a 80% reduction in required cable
width, which provides a system cost savings, reduces con-
nector physical size and cost, and reduces shielding require-
ments due to the cables’ smaller form factor.
The 21 CMOS/TTL inputs can support a variety of signal
combinations. For example, five 4-bit nibbles plus 1 control,
or two 9-bit (byte + parity) and 3 control.
Features
n Single +3.3V supply
n Chipset (Tx + Rx) power consumption <250 mW (typ)
n Power-down mode (<0.5 mW total)
n Up to 173 Megabytes/sec bandwidth
n Up to 1.386 Gbps data throughput
n Narrow bus reduces cable size
n 290 mV swing LVDS devices for low EMI
n +1V common mode range (around +1.2V)
n PLL requires no external components
n Low profile 48-lead TSSOP package
n Rising edge data strobe
n Compatible with TIA/EIA-644 LVDS standard
n ESD Rating > 7 kV
n Operating Temperature: −40˚C to +85˚C
Block Diagrams
DS90CR215
DS90CR216
Order Number DS90CR215MTD
See NS Package Number MTD48
01290901
Order Number DS90CR216MTD
See NS Package Number MTD48
01290927
TRI-STATE^® is a registered trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation DS012909
www.national.com