Rainbow Electronics MAX3798 - Manual (Page 13)

MAX3798
1.0625Gbps to 10.32Gbps, Integrated, Low-
Power SFP+ Limiting Amplifier and VCSEL Driver
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Pin Description
PIN NAME FUNCTION
1 LOS
Loss-of-Signal Output, Open Drain. The default polarity of LOS is high when the level of the input
signal is below the preset threshold set by the SET_LOS DAC. Polarity of the LOS function can be
inverted by setting LOS_POL = 0. The LOS circuitry can be disabled by setting the bit LOS_EN = 0.
2 MSEL
Mode-Select Input, TTL/CMOS. Set the MSEL pin or MODE_SEL bit (set by the 3-wire digital interface)
to logic-high for high-bandwidth mode. Setting MSEL and MODE_SEL logic-low for high-gain mode.
The MSEL pin is internally pulled down by a 75k
resistor to ground.
3, 6, 27, 30 V CCR Power Supply. Provides supply voltage to the receiver block.
4 ROUT+ Noninverted Receive Data Output, CML. Back-terminated for 50 load.
5 ROUT- Inverted Receive Data Output, CML. Back-terminated for 50 load.
7 V CCD Power Supply. Provides supply voltage for the digital block.
8 DISABLE
Transmitter Disable Input, TTL/CMOS. Set to logic-low for normal operation. Logic-high or open
disables both the modulation and bias current. Internally pulled up by an 8k
resistor to V
CC .
9 SCL Serial Clock Input, TTL/CMOS. This pin has a 75k internal pulldown.
10 SDA
Serial Data Bidirectional Input, TTL/CMOS. Open-drain output. This pin has a 75k internal pullup,
but it requires an external 4.7k pullup resistor to meet the 3-wire digital timing specification. (Data
line collision protection is implemented.)
11 CSEL
Chip-Select Input, TTL/CMOS. Setting CSEL to logic-high starts a cycle. Setting CSEL to logic-low
ends the cycle and resets the control state machine. Internally pulled down by a 75k
resistor to
ground.
12, 15, 18,
21
V CCT Power Supply. Provides supply voltage to the transmitter block.
13 TIN+ Noninverted Transmit Data Input, CML
Typical Operating Characteristics—VCSEL Driver (continued)
(V CC = 3.3V, T A = +25°C, unless otherwise specified. Figure 1 shows the typical setup used for measurements. Registers are set to
default values unless otherwise noted, and the 3-wire interface is static during measurements. For testing, the MODE_SEL bit was
used and the MSEL pin was left open.)
DETERMINISTIC JITTER
vs. PULSE-WIDTH SETTING
MAX3798 toc35
SET_PWCTRL[3:0]
DETERMINISTIC JITTER (ps)
5 3 -5 -3 -1 1
3
4
5
6
7
8
9
10
2
-7 7
PATTERN = PRBS, DATA RATE = 10.32Gbps
EYE CROSSING
DOWN UP
BIAS MONITOR CURRENT
vs. TEMPERATURE
MAX3798 toc36
TEMPERATURE ( °C)
MONITOR CURRENT (
μ
A)
80 65 -25 -10 5 35 20 50
100
200
300
400
500
600
700
800
0
-40 95
I BIAS = 12mA
I BIAS = 8mA
I BIAS = 2mA