AK2572 Datasheet, PDF (35/50 Pages) Asahi Kasei Microsystems – APC for Burst Mode Applicable Direct Modulation Laser Diode

ASAHI KASEI
[AK2572]
9.2 Write Protect Operation
Accessible range and Device address via Digital I/F are determined by Write Protect setting as shown in Table
9-1.
Table 9-1 Write Protect Operation
Item
WP = “H”
WP = “L”
R_WP_CTRL
Device address
ACK
Access to
EEPROM / Register
Operation mode
Page Write
Sequential Read
0
1
x
1010 xxx
1010 000
1010 000
When corresponding Device address is input via Digital I/F [*1]
Full Access [*2]
A0h only
Read only
A0h only
Read only
Transition to any operation mode is possible
Self-Operation Self-Operation
Mode only
Mode only
Sequential write operation of EEPROM is possible in
every 16 bytes. Sequential write operation of Register
－
－
(Address after A8h/3Eh is folded back to A8h/00h).
Sequential read operation of both EEPROM and
Register is possible within the designated address
area respectively. Address after A6h/FFh is folded Sequential read is possible in
back to A0h/00h in EEPROM and address after accessible EEPROM area.
A8h/3Fh is folded back to A8h/00h in Register.
“Non-actual space“ address is not skipped.
ï¼»*1ï¼½ ACK signal is not returned during the writing operation into EEPROM.
［*2］ When Write Protect is released (WP-pin＝“H” and R_WP_CTRL＝”0”), writing into R_PWR_SEL[1:0] at
address = A8h / 2Fh is possible in Self-Operation Mode.
About Write Protect Setting
* The data for fully accessible setting (E_WP_CTRL＝”0”, E_PASSWD＝”0”) is programmed at AKM.
(a) Write Protect operation is “ON” when WP-pin at “L”.
WP-pin setting has a higher priority than R_WP_CTRL (Register for Write Protect setting).
(b) Write Protect operation is controlled to be “ON ” or “OFF” by R_WP_CTRL when WP-pin is at “H”.
Access to R_WP_CTRL is possible only when R_PASSWD [7:0] (Register for Write Protect password), which
is loaded via digital I/F, agrees with E_PASSWD [7:0] that is the password retained in advance.
Be noted that other than “00h” should be written into E_PASSWD [7:0] to enable Write Protect.
- R_WP_CTRL＝”0” → Full access is possible
- R_WP_CTRL＝”1” → Only the area in Device address＝’1010 000（A0h）‘ is accessible (Read Only),
especially only Write Protect control register (R_PASSWD, R_WP_CTRL) are writable
Accordingly, when Self-Operation Mode is set by R_WP_CTRL＝“1”, access to the adjusting data is executed
as the following procedure,
(1) Make it enable to access to R_WP_CTRL by setting the same value to R_PASSWD as is retained in
E_PASSWD in advance.
(2) Set R_WP_CTRL＝ “0” to enable full access.
(3) When to modify EEPROM content, shift the mode into EEPROM Access Mode and then modify data.
At the Power-on or when Self-Operation Mode is set, R_PASSWD is reset to “00h” and E_WP_CTRL value
is loaded to R_WP_CTRL. So, if E_WP_CTRL is set to “0”, Write Protect operation is automatically released
at Power-on or when Self-Operation Mode is set.
Table 9-2 Write Protect Control Register / EEPROM
Register
EEPROM D7 D6 D5
A0h / 7Eh
A6h / 7Eh
－－－
A0h / 7Fh
A6h / 7Fh
D4 D3 D2
－－－
PASSWD
D1
D0
－ WP_CTRL
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2004/8