AK2573A Datasheet, PDF (17/38 Pages) Asahi Kasei Microsystems – 125M / 156M Laser Diode Driver + APC

ASAHI KASEI
[AK2573A]
Table 4-4 Example of APC FF and APC FB combination
RE_APC_ RE_APC_ BIAS MOD Remarks
FF_SET FB_SET (I-DAC2) (I-DAC1)
Reference
01
10
FB
FF The initial value of APC FB according to the Fig 4-4
temperature can be set to accelerate power up time.
10
01
FF
FB The initial value of APC FB according to the Fig 4-5
temperature can be set to accelerate power up time.
11
00
FF
FF Both BIAS and MOD current are detrmined by Fig 4-6
APC_FF. APC_FB is not work.
11
01
FF FF+FB Both BIAS and MOD current are detrmined by Fig 4-7
APC_FF. APC_FB is set to MOD for LD aging.
11
10
FF+FB FF Both BIAS and MOD current are detrmined by Fig 4-8
APC_FF. APC_FB is set to BIAS for LD aging.
01
11
FB FF+FB Dual Feedback function.
Fig 4-9
BIAS current is determined by APC_FB. MOD
current is determined by APC_FF and APC_FB.
The initial value of APC_FB according to the
temperature can be set to accelerate power up time.
10
11
FF+FB FB Dual Feedback function.
Fig 4-10
MOD current is determined by APC_FB. BIAS
current is determined by APC_FF and APC_FB.
The initial value of APC_FB according to the
temperature can be set to accelerate power up time.
00
11
-
-
Prohibit
11
11
-
-
Prohibit
RE_APC_FF_SET (Register or EEPROM) is composed of 2-bits. MSB shows BIAS (I-DAC2) and LSB shows MOD
(I-DAC1), and “1” indicates APC Feed-forward function is selected.
RE_APC_FB_SET (Register or EEPROM) is composed of 2-bits. MSB shows BIAS (I-DAC2) and LSB shows MOD
(I-DAC2), and “1” indicates APC Feedback function is selected.
Fig 4-4 APC example-1 (MOD=FF, BIAS=FB)
R_APC_FB
R_DAC1_FF
RE_DAC1_GAIN
I-DAC1
R_DAC1_FB
=0
R_DAC1
0
+
85/255
G_DAC1
Imod
I-DAC2
R_DAC2_FB
= R_APC_FB
R_DAC2
1
+
54/255
G_DAC2
Ibias
R_DAC1 = R_DAC1_FF
R_DAC2 = R_DAC2_FB = R_APC_FB
R_DAC2_FF = 0
RE_DAC2_GAIN
G_DAC1/G_DAC2 = 1 or 0.5
Fig 4-5 APC example-2 (MOD=FB, BIAS=FF)
R_APC_FB
R_DAC1_FF =
0
I-DAC1
RE_DAC1_GAIN
R_DAC1_FB
= R_APC_FB
R_DAC1
1
+
85/255
G_DAC1
Imod
I-DAC2
R_DAC2_FB
=0
R_DAC2
0
+
54/255
G_DAC2
Ibias
R_DAC1 = R_DAC1_FB = R_APC_FB
R_DAC2 = R_DAC2_FF
R_DAC2_FF
RE_DAC2_GAIN
G_DAC1/G_DAC2 = 1 or 0.5
Fig 4-6 APC example-3 (MOD=FF, BIAS=FF)
R_APC_FB
R_DAC1_FF
RE_DAC1_GAIN
I-DAC1
R_DAC1_FB
=0
R_DAC1
0
+
85/255
G_DAC1
Imod
I-DAC2
R_DAC2_FB
=0
R_DAC2
0
+
54/255
G_DAC2
Ibias
R_DAC1 = R_DAC1_FF
R_DAC2 = R_DAC2_FF
R_DAC2_FF
RE_DAC2_GAIN
G_DAC1/G_DAC2 = 1 or 0.5
<MS0189-E-01>
-17-
2004/5