ak2573a AKM Semiconductor, Inc., ak2573a Datasheet - Page 16

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

response to the temperature from an on-chip temperature sensor (every 6#, APC reference data is stored in
E_APC_TRGT_TC, see Table 8-3 for more information). Write same data into E_APC_TRGT_TC for constant APC
reference. Table 4-3 shows the relationship between APC reference voltage (vapc_ref) and EEPROM setting.
RE_APC_FF and RE_A PC_FB. Fig 4-5 shows the EEPROM area for MOD current (E_DAC1_TC) and BIAS
current (E_DAC2_TC). The data should be stored in E_DAC1_TC and E_DAC2_TC is determined by RE_APC_FF
and RE_APC_FB. Table 4-7 and 4-8 shows all combination of APC function.
DACA PC generates the reference voltage of APC (vapc_ref). AK2573A supplies a programmed APC reference in
Table 4-3 DACA PC
Table 4-4 shows the typical setting of APC function (APC_FF and APC_FB). The combination of APC is set by
RE_APC_FF is 2bit data to be assigned I-DAC for APC_FF operation. MSB is for I-DA C2 and LSB for I-DAC1.
RE_APC_FB is 2bit data to be assigned I-DAC for APC_FB operation. MSB is for I-DAC2 and LSB for I-DAC1.
In the case of RE_APC_FB=11(binary), AK2573A is in “ Dual Feedback” (see Fig 4-9, 4-10 and Table 4-6).
ASAHI KASEI
4.2.1 PDGAIN
PD monitor current is converted to the average voltage with RPD and CPD and input to PDIN. PDIN voltage may be
Table 4-1 PDIN input range
Table 4-2 PDGAIN
4.2.2 DACAPC
4.2.3 Example of APC Setting
<MS0189-E-01>
gained at PDGAIN and monitored at PDMON. PDGAIN should be adjusted to PDMON = 1V typ. The gain range
of PDGAIN is –8.0dB to 23.5dB with 0.5dB steps (6-bits). PDGAIN is set via the I
PDIN input range and Table 4-2 shows the relationship between PDGAIN and EEPROM setting.
PDIN Input range
RE_PDGAIN_SET
E_A PC_TRGT_TC
(R_APC_TRGT)
111110 (62)
111111 (63)
Parameter
000000 (0)
000001 (1)
01111 (15)
10000 (16)
10001 (17)
11111 (31)
00000(0)
:
:
:
Gain (typ) [dB]
DACA PC (vapc_ref) (typ) [V]
0.08V
min
23.5
23.0
-7.5
-8.0
:
0.792
0.987
1.013
1.195
1.0
Remark
0.5dB step
max
2.5V
-16-
Remark
13mV step
Remark
2
C
TM
interface. Table 4-1 shows
[AK2573A]
2004/5