LTC5100 datasheet(27/52 Pages) LINER

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LTC5100

sn5100 5100fs

by an on-chip temperature sensor or by an external

microprocessor, according to the setting of Ext_temp_en.

The temperature compensated expression for Ib_set is

given by:

Ib set

Ib nom

Ib tc

•

_•

•

_•

•

–

∆

+∆ +













(29)

Ib_tc1 and Ib_tc2 are the first and second order tempera-

ture coefficients for the laser bias current.

TRANSMIT ENABLE, FAULT DETECTION

AND EYE SAFETY

The LTC5100 is compatible with the Gigabit Interface

Converter (GBIC) specification, but includes additional

features and safety interlocks. Figure 27 shows the state

diagram for enabling the transmitter and detecting faults.

The EN pin and Soft_en control bit enable and disable the

transmitter. The EN pin may be programmed for active

high or active low operation with the En_polarity bit.

OPERATIO

READY

(DISABLED)

SETTLING

(ENABLED)

READ

EEPROM

WAIT

64ms

SETTLED

(ENABLED)

READY

(SETTLED

AND

DISABLED)

FAULTED

(DISABLED)

POWER ON RESET OR

Operating_mode = 0

SUCCEEDED OR

Operating_mode = 1

100ms

TIMEOUT

ENABLE AND

Rapid_restart_en = 0

ENABLE

Transmitter_enabled = 0

FAULT DETECTION DISABLED

Transmitter_enabled = 1

FAULT PIN ASSERTED

Transmitter_enabled = 0

Transmit_ready = 0

Faulted = 1

SETTLING

(ENABLED)

FAULT DETECTION DISABLED

Transmitter_enabled = 1

SETTLING

(ENABLED)

FAULTED

TWICE

(DISABLED)

FAULT DETECTION ENABLED

Transmit_ready = 1

POWER ON RESET

5100 F27

Faulted = 1

Faulted_once = 1

Faulted_twice = 1

Faulted = 0

Faulted_once = 1

25ms

TIMEOUT

100ms

TIMEOUT

Transmitter_enabled = 0

Transmit_ready = 0

FAULT

FAULT DETECTION ENABLED

Transmit_ready = 1

FAULT DETECTION DISABLED

Transmit_ready = 1

ENABLE = EN AND Soft_en

FAULT = Over_current OR

Over_power OR

Under_power

FAILED

TIMEOUT

Mem_load_error = 1

Operating_mode = 1

READY

(DISABLED)

ENABLE

FAULT

SETTLING

(ENABLED)

ENABLE

Faulted_once = 0

ENABLE

40ms

TIMEOUT

ENABLE AND

Rapid_restart_en = 1

ENABLE AND

Rep_flt_inhibit = 0

ENABLE AND

Rep_flt_inhibit = 1

Figure 27. State Diagram for Transmitter Enable and Fault Detection

LTC5100 Datasheet(PDF) 27 Page - Linear Technology

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