ak2573a AKM Semiconductor, Inc., ak2573a Datasheet - Page 23

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

Fig 6-1 shows the shutdown operation. The AK2573A supports the SFP (Small Form-factor Pluggable) requirement.
Fig 6-1 Shutdown Operation
ASAHI KASEI
RE_SFP = 0 operation
RE_SFP=1 operation
6. Shutdown
6.1 Shutdown Operation
Fig 6-2 Shutdown Condition
6.2 Temperature Comparison between Shutdown Request and Release
<MS0189-E-01>
The AK2573A keeps the temperature data at shutdown request and compares it with temperature at release request
to avoid over-current conditions at the LD. When the AK2573A detects a temperature difference between at
shutdown request and the release request, the APC FB data is set to 0 or to initial values in response to the
temperature at the release request. The temperature difference is programmable.
When the AK2573A does not detect a temperature difference, it keeps the APC FB data, resulting in faster operation.
This function works at release request as follows:
if (ABS(R_TEMP_STDW – R_TEMP)) > R_TEMP_WIN)
APC FF continues to operate during shutdown for fast performance when a release request is received. However, the
I-DAC current stays at 0mA.
Function
I-DA C1 / 2 output
APC_FF
APC_FB
ALM
TXFAULT
Set “ H” when OPTALM, CURRALM, TEMPALM or DATAALM is detected
Set “ L” when no ALM detected.
Support TX_FAULT of the SFP (Small Form-factor Pluggable) requirement.
Set and hold “ H” when detected OPTALM, CURRALM, TEMPALM or DATAA LM and go into shutdown
mode.
Reset to “ L” when TXDIS1 or TXDIS2 is “ H“ * “ L” . Refer to “ 6. Shutdown” for more information.
During “Adjustment mode” , TXFAULT detection is ignored.
TXDIS1
X
R_APC_FB = 0 or reset to the initial value in response to the R_TEMP
where, R_TEMP_STDW is a temperature at shutdown request
1
0
0
0
R_TEMP is a temperature at release request
R_TEMP_WIN is a temperature difference (user programmable)
TXDIS2
X
1
0
0
0
High-Z (0mA output)
Normal Operation.
Keep the data at shutdown request.
Normal Operation
R_SFP=0: Normal Operation
R_SFP=1: Keep the data at shutdown request.
Operation
RE_SFP
X
X
0
1
1
TXFAULT
X
X
X
0
1
-23-
Shutdown
Shutdown
Normal Operation
Normal Operation
Shutdown
Operation
Remarks
Shutdown with pin
Shutdown with pin
SFP TXFAULT
Operation
Remarks
[AK2573A]
2004/5