MAX3982 查看數據表（PDF） - Maxim Integrated
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MAX3982 Datasheet PDF : 15 Pages
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SFP Copper-Cable Preemphasis Driver
VCC2
VCC2
10kΩ
MAX3982
PE0
2
PE1
LVTTL
2
VCC1
LIMITER
IN+
FIXED
CML
EQUALIZER
IN-
LOSLEV
TX_DISABLE
OUTLEV
VCC1
40kΩ
VCC2
10kΩ
VCC2
40kΩ
VCC1
LVTTL
VCC2
LVTTL
VCC2
LVTTL
PREEMPHASIS CML
SIGNAL DETECT
VCC2
OUT+
OUT-
LOS
GND
Figure 4. Functional Diagram
Detailed Description
The MAX3982 comprises a PC board receiver, a cable
driver, and a loss-of-signal detector with adjustable
threshold (Figure 4). Equalization is provided in the
receiver. Selectable preemphasis and selectable output
amplitude are included in the transmitter. The MAX3982
also includes transmit disable control for the output.
PC Board Receiver and Cable Driver
Data is fed into the MAX3982 through a CML input
stage and fixed equalization stage. The fixed equalizer
in the receiver corrects for up to 10in of PC board loss
on FR4 material at 4.25Gbps.
The cable driver includes four-state preemphasis to
compensate for up to 15m of 24AWG, 100Ω balanced
cable. Table 1 is provided for easy translation between
preemphasis expressions. The OUTLEV pin selects the
output amplitude. When OUTLEV is low, the amplitude
is 1200mVP-P. When OUTLEV is high, the amplitude is
1600mVP-P. Residual jitter of the MAX3982 is indepen-
dent of up to 0.20UIP-P source jitter.
Loss-of-Signal (LOS) Output
Loss-of-signal detection is provided on the data input.
Pullup resistors should be connected from LOS to a
supply in the range of +3.0V to +5.5V. The LOS output
is not valid until power-up is complete. Typical LOS
response time is 100ns.
The LOS assert and deassert levels are set by the
LOSLEV pin. When LOSLEV is LVTTL high or open, the
LOS assert threshold is 180mVP-P. When LOSLEV is
LVTTL low, the LOS assert threshold is 85mVP-P.
TX Disable
Transmit disable is provided to turn off the output when
desired. The TX_DISABLE pin can be connected to
LOS to automatically squelch the output when the
incoming signal is below the threshold set by LOSLEV
(see the Autodetect section).
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