Rainbow-electronics MAX3646 Manuale Utente Scaricare il pdf (Pagina 9)

MAX3646

155Mbps to 622Mbps SFF/SFP

Laser Driver with Extinction Ratio Control

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If any of the I/O pins are shorted to GND or V

(single-point failure; see Table 2), and the bias current or the photocurrent

exceeds the programmed threshold.

End-of-life (EOL) condition of the laser diode. The bias current and/or the photocurrent exceed the programmed threshold.

Laser cathode is grounded and photocurrent exceeds the programming threshold.

No feedback for the APC loop (broken interconnection, defective monitor photodiode), and the bias current exceeds the

programmed threshold.

Table 1. Typical Fault Conditions

BC_MON

PC_MON

COMP

REF

TTL

OPEN COLLECTOR

CMOS

SHUTDOWN

TX_FAULT

LATCH

COUNTER

60ms DELAY

POR AND COUNTER

60ms DELAY

100ns DELAY

BIAS

ENABLE

MOD

ENABLE

TX_DISABLE

COMP

EXCESSIVE

APC CURRENT

SETPOINT

EXCESSIVE

MOD CURRENT

SETPOINT

BIAS

Figure 5. Simplified Safety Circuit

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Rainbow-electronics MAX3646 Manuale Utente Pagina 9