AK2574 Datasheet, PDF (13/30 Pages) Asahi Kasei Microsystems – 156M Laser Diode Driver + APC for Burst Mode

ASAHI KASEI
[AK2574]
Ⅵ. Circuit Description
1. Parameter Notation
1.1 Parameter Definition
In the AK2574 Circuit Description, in order to distinguish various pre-set parameter sources from EEPROM,
Registers or Device pins, “Identifier - Main name” notation is used as shown in Table 1-1. For ease of operational
description, small letters sometimes expresses internal signals.
Table 1-1 Parameter Definitions
Identifier
Register
R_
EEPROM
E_
Ether or both Register RE_
or /and EEPROM
PIN
P_
BLOCK
None
Internal Node
None
Main Name
REGISTER name
(All Capital)
EEPROM name
(All Capital))
REGISTER /
EEPROM name
(All Capital)
PIN name
(All Capital)
BLOCK name
(All Capital))
signal name
(small letter)
Remark
Indicates register
Example
R_DAC1
Indicates EEPROM E_DAC1
Indicates either register RE_DAC1
or EEPROM
P_PDIN
I-DAC1
txact_ref
1.2 Operation Overview
The AK2574 has 3 primary functions; 125M / 156M modulation (MOD) current switching and BIAS current
switching part, APC (Automatic Power Control) part, and the Control part to control operation modes of the AK2574
operation.
There are 3 operation modes in the AK2574. Since each adjusting function is controlled through I²C^TM Interface, it
realizes an automatic parameter adjustment.
(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.
(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.
(3) EEPROM Mode
EEPROM modeis used for storing LD characteristics into EEPROM via I²C^TM I/F.
<MS0266-E-00>
-13-
2003/12