AK2573A Datasheet, PDF (22/38 Pages) Asahi Kasei Microsystems – 125M / 156M Laser Diode Driver + APC

ASAHI KASEI
[AK2573A]
5. Alarm
AK2573A has 5 alarm functions as shown in Table 5-1.
Table 5-1 Alarm function
ALM
Detection condition
Polarity
Detected Time
OPTALM
When monitor PD current is below the OPTALM level.
Programmable 5us (typ) (Note 1)
CURRALM When R_DAC1 or R_DAC2 is beyond CURRALM level or Programmable every 125us (typ)
equal to full code.
TEMPALM When the detected temperature is beyond TEMPALM Programmable every 128ms (typ)
level.
DATAALM When the detected 0s or 1s sequential data input (4.5us Programmable 4.5us (typ)
typical).
TXFAULT When one or more alarm detected.
“H”
depends on
detected ALM
Note 1: Not include delay time by RPD and CPD.
5.1 OPTALM
OPTALM level (optalm_ref) is selectable among 1/3, 1/4, 1/6 and 1/7 of APC FB reference voltage (vapc_ref) by
RE_OPTALM.
OPTALM is detected when vpd < optalm_ref.
APC FB keeps R_APC_FB during OPTALM detection in the“Self running mode”.
5.2 CURRALM
CURRALM is detected when
R_DAC1(MSB 4bit) > R_CURRALM_DAC1 or R_DAC2(MSB 4bit) > R_CURRALM_DAC2
R_CURRALM_DAC1 and 2 can be set every 6℃.
CURRALM is clear when receiving disable request (TX_DIS1 or TX_DIS2 is set “H”).
5.3 TEMPALM
TEMPALM is detected when R_TEMP < R_TEMPALM.
R_TEMP has negative slope compared to the temperature, TEMPALM is detected when the detected temperature
beyond R_TEMPALM.
5.4 DATAALM
DATAALM is detected when input DATA is 0’s or 1’s fixed more than 4.5us (typ).
APC FB keeps R_APC_FB during DATAALM detection in the“Self running mode”.
DATAALM detection is ignored when RE_DATAALM_MASK= “1”.
5.5 TXFAULT
TXFAULT function is shown in Table 5-2.
Table 5-2 TXFAULT
RE_SFP Shutdown request
(TXDIS 1, 2)
0
0
0
0
0
1
1
0
1
0
1
1
ORed ALM TXFAULT
I-DAC output
0
0
Normal Operation
1
1
Normal Operation
X
ORed ALM Shutdown
0
0
Normal Operation
1
1 (Hold) Shutdown
X
0 or 1 (Hold) Shutdown
<MS0189-E-01>
-22-
2004/5