ak2573a AKM Semiconductor, Inc., ak2573a Datasheet - Page 36

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

ASAHI KASEI
10. Module Adjustment Example
Table 10-1 shows the module adjustment example.
Table 10-1 Module Adjustment Example
<MS0189-E-01>
No.
1
2
3
4
5
6-A
6-B
7
8
9
10
11
12
Item
Go to Adjustment mode
SFP setting
APC setting
LD current adjustment
Duty adjustment
PDGAIN adjustment
PDGAIN adjustment
APC FB setting
APC FB target
adjustment
Read temperature data
Estimate LD temperature
characteristics
Write adjustment data to
EEPROM
Self running mode
Contents
Issues “ Changing to Adjustment mode command” (see Table 9-2) via
I
Set R_SFP = 0 to avoid TXFAULT detection at adjustment mode.
Set R_APC_FB_SET = ” 00” and R_APC_FF=11. BIAS and MOD
current is set as “ Open Loop” .
Set
R_APC_FF_DAC1 for modulation current and R_APC_FF_DAC2 for
BIAS current of LD.
Adjust R_DUTY for 50% duty of LD power, if necessary. After duty
adjustment, tune MOD and BIAS current by R_APC_FF_DA C1 and 2, if
necessary.
Adjust R_PDGAIN for PDMON = 1V. Go to step -7.
If you cannot measure PDMON voltage, see step 6 -B.
Set R_APC_TRGT=100000 and R_PDGAIN=000000 (Gain=23.5dB).
Then set R_APC_FF_SET and R_A PC_FB_SET as your configulation.
APC FB adjusts LD output automatically. A djust R_PDGAIN for
normal LD output. R_A PC_TRGT adjustment is for fine tunning of
optical power. Go to step-8.
Set R_APC_TRGT = “ 10000” .
Set R_APC_FB_SET according to your configuration.
Adjust R_A PC_TRGT to tunning LD output. LD output is adjusted
automaticaaly according to the R_APC_TRGT.
Read R_TEMP (on-chip temperature sensor detection temperature).
(1) 2 or more temperature adjustment
Do step 2 to 8 with different temperature and estimate LD current data of
look-up table.
(2) Single point adjustment
Calculate LD current data of look-up table with on-chip temperature
sensor gain (-1.49#/LSB), R_TEMP and LD characteristics.
(1) Make the data for EEPROM.
(2) Issue mode change command to EEPROM.
(3) Write adjustment data to EEPROM.
(4) Read EEPROM data and verify it.
Issue mode change command to self-running. AK2573A operates
temperature detection, feed current in response to temperature, and a
feedback operation automatically according to the data in EEPROM.
2
C
T M
I/F.
R_DAC1_GAIN
-36-
and
R_DAC2_GAIN,
then
[AK2573A]
adjust
2004/5