ak2573a AKM Semiconductor, Inc., ak2573a Datasheet - Page 24

• Manufacturer Part Number: ak2573a
• Description: 125m / 156m Laser Diode Driver Apc - Asahi Kasei Microsystems
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
7.1 Delay Time of TXFAULT Detection with OPTALM
In correspond to the delay time caused by RPD and CPD to get the moniter PD average current, the delay time of
TXFAULT detection with OPTALM is set when RE_SFP=” 1” (SFP support). AK2573A has 2 delay time when
RE_SFP=” 1” : normal delay and accelerated delay. Accelerated delay may be selected when both I-DAC1 and I-DAC2
are set to APC_FF or APC_FB with an initial value setting.
Table 7-1 shows the delay time of TXFAULT detection with OPTALM and Fig 7-1 illustrated block diagram.
Note: When accelerated delay is selected with RE_SFP=” 1” , APC_FF data or initial data of APC_FB should be
Fig 7-1 APC_FB Block Diagram
Table 7-1 Delay time of TXFAULT detection with OPTALM
<MS0189-E-01>
Table 6-3 Operation at shutdown release
7. Power-up / down Timing
LD
RE_SFP
Detection and reset OPTALM
vary with the cut-off
frequency of CPD and RPD
RE_SFP
0
1
1
1
1
0
0
0
1
1
1
1
suitable, otherwise AK2573A might go into shutdown by detection of OPTALM after delay time.
CPD
TXFAULT at
Shutdown request
Monitor
R_TIMER_
OPTALM
X
0
1
1
1
RPD
PD
X
X
X
0
0
0
1
(R_APC_TRGT
PDIN
APC Terget
)
(R_PDGAIN)
PDGAIN
PDGAIN
R_A PC_
INIT_SET
X
X
0
X
1
DAC_APC
RE_TEMP_
DET
vpd
X
0
1
1
0
1
1
vapc_ref
R_A PC_
FF_SET
X
X
00
01
10
11
X
Temp Difference
result
OPTALM Level
COMP
APC_
(R_OPTALM)
ATT
X
X
X
Delay Time of TXFAULT
detection with OPTALM
0 ms
160 ms (typ)
160 ms (typ)
2 ms (typ)
2 ms (typ)
0
1
0
1
(opalm_ref)
OPTALM
-24-
reference
Digital
Filter
R_A PC_FB
Initial value
Hold data
Initial value
Initial value
Hold data
Initial value
Initial value
APC Feedback
OPTALM
(R_APC_FB)
Remarks
disable TX FAULT
detection
Acceleration
power-up
TX_FAULT
Control
Remark
[AK2573A]
2004/5