AK2574VB AKM [Asahi Kasei Microsystems], AK2574VB Datasheet - Page 28

• Manufacturer Part Number: AK2574VB
• Description: 156M Laser Diode Driver + APC for Burst Mode
• Manufacturer: AKM [Asahi Kasei Microsystems]

7. Module Adjustment Example
Table 7-1 shows the module adjustment example.
Table 7-1 Module Adjustment Example
<MS0266-E-00>
No. Item
1
2
3
4
5
6
7
8
9
10
Go to Adjustment mode
Continuous operation
LD current adjustment
Duty adjustment
TXACT adjustment
Verification of TXACT
Read temperature data
Estimate LD temperature
characteristics
Write adjustment data to
EEPROM
Self running mode
Contents
Issues “Changing to Adjustment mode command” (see Table 5-2) via I
Set BRST=”H” to operate AK2574 as a continuous operation.
Adjust R_DAC1 for modulation current and R_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_DAC1 and R_DAC2, if
necessary.
Adjust LD power by R_DAC1 and R_DAC2 to 3dB down of minimum LD
power that you would like to detect TXACT. Input the burst control signal and
adjust R_DAC_TXACT for tunning TXACT detection time. For more
information, see “3.1 TXACT”.
Set R_DAC1 and R_DAC2 back to normal power. Confirm TXACT detection
time.
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. AK2574 operates temperature
detection, feed current in response to temperature, and a feedback operation
automatically according to the data in EEPROM.
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2003/12
C
TM
I/F.