+3.3V, 622Mbps, SDH/SONET
1:8 Deserializer with TTL Outputs
PECL Inputs
The serial data and clock PECL inputs (SD+, SD-,
SCLK+, SCLK-) require 50Ω termination to (VCC - 2V)
when interfacing with a PECL source (see Alternative
PECL Input Termination).
__________Applications Information
Alternative PECL Input Termination
Figure 4 shows alternative PECL input-termination
methods. Use Thevenin-equivalent termination when a
(VCC - 2V) termination voltage is not available. If AC
coupling is necessary, such as when interfacing with
an ECL-output device, use the ECL AC-coupling termi-
nation.
Layout Techniques
For best performance, use good high-frequency layout
techniques. Filter voltage supplies and keep ground
connections short. Use multiple vias where possible.
Also, use controlled impedance transmission lines to
interface with the MAX3680 data inputs.
__________________Pin Configuration
THEVENIN-EQUIVALENT TERMINATION
+3.3V
130Ω
ZO = 50Ω
130Ω
MAX3680
ZO = 50Ω
PECL
INPUTS
82Ω
82Ω
+3.3V
ZO = 50Ω
ECL AC-COUPLING TERMINATION
1.6k
1.6k
MAX3680
50Ω
ZO = 50Ω -2V
PECL
INPUTS
TOP VIEW
VCC 1
VCC 2
SD+ 3
SD- 4
VCC 5
SCLK+ 6
SCLK- 7
VCC 8
GND 9
SYNC 10
GND 11
GND 12
PCLK 13
VCC 14
MAX3680
SSOP
28 PD7
27 GND
26 PD6
25 VCC
24 PD5
23 GND
22 PD4
21 PD3
20 GND
19 PD2
18 VCC
17 PD1
16 GND
15 PD0
50Ω
2.7k
2.7k
-2V
Figure 4. Alternative PECL Input Termination
___________________Chip Information
TRANSISTOR COUNT: 1346
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