AK2572 Datasheet, PDF (28/50 Pages) Asahi Kasei Microsystems – APC for Burst Mode Applicable Direct Modulation Laser Diode

ASAHI KASEI
[AK2572]
6. 5 TXFAULT
6.5.1 Target Alarm Setting of TXFAULT Output
As shown in Table 6-2, target Alarms (ALMs) available on TXFAULT output can be selected by EEPROM /
Register setting. Logical “OR” function of the selected ALMs becomes TXFAULT output signal.
Table 6-2 Target ALM Setting of TXFAULT Output
Target ALM
Mask setting [*1]
Device Address / Address
EEPROM Register
Status register
(A8h / 19h) [*2]
Note
EXTALM2 RE_EXTALM2_SETï¼»5ï¼½
R_TXFLT_ST [3]
[*3]
EXTALM1 RE_EXTALM1_SETï¼»4ï¼½
CURRALM RE_CURRALM _SETï¼»3ï¼½
A6h / 65h
A8h / 05h
R_TXFLT_ST [2]
R_TXFLT_ST [1]
OPTALM RE_OPTALM _SETï¼»2ï¼½
R_TXFLT_ST [0]
TEMPALM RE_TEMPALM_SETï¼»7ï¼½ A6h / 66h A8h / 06h
R_TXFLT_ST [4]
［*1］Logical “OR” function of those ALMs, where corresponding bits are set by “1” in mask setting by
EEPROM / Register, becomes TXFAULT output signal.
［*2］When ALM is detected, “1” is written in the corresponding bit of the ALM.status register.
［*3］When RE_PWR_LVL1_SET＝”0” or RE_SFP_SET＝”0”, EXTALM2 / MOD_CTRL-pin is set as
EXTALM2 input pin and EXTALM2 function is enabled.
6.5.2 Operation at TXFAULT Detection
Operation at TXFAULT detection differs by RE_SFP_SET setting. Operation at different settings is listed in
Table 6-3.
When at RE_SFP_SET＝”0”, any of the ALMs being set by EEPROM / Register is detected, TXFAULT signal
is generated and “H” output is held and DAC output is put into shutdown condition. But when a shutdown
request is made via TXDIS-pin, a previous TXFAULT output level before the shutdown request is kept and
even if any ALM is detected during the shutdown, TXFAULT signal is not output. When the shutdown
request is released (transition of “L” to “H”) via TXDIS-pin, release of TXFAULT (TXFAULT output is “L”) is
made. For more details, please refer to section “7. Shutdown Control“. DAC output is not shutdown during the
Adjustment Mode even if TXFAULT is detected.
When at RE_SFP_SET＝”1”, any of the ALMs being set by EEPROM / Register is detected, TXFAULT signal
is generated (TXFAULT output is “H”), when all selected ALMs are cleared, TXFAULT is also cleared
(TXFAULT output is “L”).
When the shutdown condition is set, CURRALM is forced to “Disabled output“ state.
Table 6-3 TXFAULT Operation
Shutdown Logical “OR” of
RE_SFP_SET request via target ALM for
TXDIS-pin TXFAULT
0
0
0
1
1
x
0
x
1
1
x
TXFAULT
Operation
0
1 (Hold)
Hold the previous TXFAULT level
just before shutdown request
Logical “OR” of target ALMs for
TXFAULT
Logical “OR” of target ALMs for
TXFAULT
Normal operation
Shutdown
Shutdown
Normal operation
Shutdown
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< MS0290-E-01>
2004/8