AK2574 Datasheet, PDF (18/30 Pages) Asahi Kasei Microsystems – 156M Laser Diode Driver + APC for Burst Mode

ASAHI KASEI
[AK2574]
Table 2-6 I-DAC2 Characteristics
Item
Condition
min
Resolution
Maximum Output
IBIAS = VDD – 1.8V 48
Current
R_DAC2=FFh
Minimum Output
IBIAS = VDD
Current 1
Minimum Output
1 ≤ R_DAC2 ≤ 5
IBIAS = VDD
Current 2
R_DAC2 = 0
1 LSB Current Step IBIAS = VDD – 1.8V
DNL
IBIAS = VDD – 1.8V -1
typ
max Unit Remark
8
bit
54
60
mA
1.06
1.2 mA See 2.4.3
0
mA
0.212
mA
+1 LSB Code 20h to FFh
2.4.3 I-DAC2 Minimum Current Output
Table 2-7 shows the relationship between EEPROM setting (E_DAC2_TC) and I-DAC2 code (R_DAC2). The data to
be set to I-DAC2 (R_DAC2) is limited to 5 or more for BIAS current circuit stability. From 1 to 5 code is changed to 5
andissettoI-DAC2. Inthecaseof0code,BIASdriveristurnedoffandIBIASpinisHi-Z.
Table 2-7 I-DAC2 Code Setting
E_DAC2_TC
0
1～4
R_DAC2 (I-DAC2 code)
BIAS Driver = OFF
5
5 or more
E_DAC2_TC
Remarks
IBIAS = Hi-Z
Code 1 to 4 is forced to be 5
No modification
2.4.4 Temperature Sensor (TEMPSENS)
Fig 2-8 shows an on-chip temperature sensor characteristics and Table 2-8 shows the relationship between detected
temperature and ADC code.
Fig 2-8 On-chip Temperature Sensor Characteristics
On-chip Temperature sensor characteristics
2.5
2.0
1.5
1.0
0.5
0.0
-40
-20
0
20
40
60
Temperature t [°C]
80
100 120
(1) Slope: -11.56mV/℃ (typ)
(2) V(t) = -0.01156 * t + 1.62 [V] (typ)
(3) AD_code = int( V(t) / 2.2 * 127 +0.5) = int(-0.667*t + 94.0)
(4) Temperature step @ AD_code=1LSB: 1.49℃/LSB
Note: Temperature sensor detects the junction temperature, not LD or ambient temperature.
<MS0266-E-00>
-18-
2003/12