AK2574 Datasheet, PDF (27/30 Pages) Asahi Kasei Microsystems – 156M Laser Diode Driver + APC for Burst Mode

ASAHI KASEI
[AK2574]
6. Operation Mode
The AK2574 has 3 operating modes: Self-running, Adjustment and EEPROM mode.
6.1 Self-running Mode
Self-running mode is ready for normal operation after all adjustments are completed. In this mode, temperature
detection, EEPROM access and feeding current are automatically performed using the on-chip oscillator. The
AK2574 works in this mode after power-on.
6.2 Adjustment Mode
Adjustment mode is designed for training the LD characteristics. The AK2574 operates according to the register
settings set through the I²C^TM I/F.
6.3 EEPROM Mode
EEPROM mode is used for storing LD characteristics into EEPROM. Transition from EEPROM mode to
Adjustment mode is prohibition.
6.4 MODE Control
The AK2574 operation modes are changed through the I²C^TM interface. Table 6-1 shows the access limitation of each
operation mode and Table 6-2 shows the command to change operation mode.
Note: The I²C^TM interface access is prohibited for 2ms after power-on or mode transfer to self-running mode.
Table 6-1 Access limitation of each operation mode
EEPROM Access
Operation mode
Read
Write
Self-running mode
○
×
(WP=”L”)
Adjustment mode
(WP=”L”)
○
×
EEPROM mode
(WP=”L”)
○
○
WP = “H”
○
×
Self-running mode only _{(User Area Only)}
Read
○
○
○
×
Register Access
Write
×
(except mode-change command)
○
×
(except mode-change command)
×
Table 6-2 Operation mode change
Device Address R/W
1010100
W
1010100
W
1010100
W
Address
11111111
11111111
11111111
Data
10100000
10100111
10101110
Operation mode
Self-running mode
Adjustment mode
EEPROM mode
6.5 Operation Mode Protection
When set WP = “H”, only self-running mode is selected.
6.6 Operation Mode Status
Operation mode is stored in R_MODE register. Table 6-3 shows the relationship between the Operation mode and
R_MODE. When set WP = “H”, access to R_MODE is prohibition.
Table 6-3 R_MODE
Operation mode
Self-running mode
Adjustment mode
EEPROM mode
R_MODE[3:0]
0000
0111
1110
<MS0266-E-00>
-27-
2003/12