AK2571 Datasheet, PDF (18/52 Pages) Asahi Kasei Microsystems – Single-Chip Automatic Power/Temperature Control for WDM Laser Diodes

AKM Confidential
Figure 4-7 PWM division
Case-1
PID control value(R_PID_VALABS) = 2020
PWM division = 32
8192/32=256
TS#1
64
TS#2
64
TS#3
64
64*4 + 63*28 = 2020
TS#4
64
TS#5
63
TS#6
63
Operation cycle (8ms typ)
Resolution=8192
Minimum pulse width = 8ms/819≅21us
63
1us
64
256
AK2571
TS#32
63
Case-2
PID control value(R_PID_VALABS) = 2020
PWM division = 64
8192/16=128
32*36 + 31*28 = 2020
TS#1 TS#2 TS#3 TS#4 TS#5 TS#6 TS#7 TS#8 TS#9
32
32
32
32
32
32
32
32
32
Operation cycle (8ms typ)
TS#61 TS#62 TS#63 TS#64
31
31
31
31
4.4 Gain & Offset
The AK2571 amplifies (typically x13) the input signal from the thermister to provide higher resolution for the 8-bit ADC. It
also adds an offset voltage to meet the middle of full scale at target temperature. Table 4-6 indicates temperature levels
that correspond to ADC values when using a thermister R0=10kohm@25degree, B=3900 and Table 4-7 indicates a
thermister R0=10kohm@25degree, B=3450. Both load resistances RL) are 6.8kohm, REFOUT is 2.3V. When adjusting
Offset voltage (R_ATC_OFFSET), target temperature must be a value between 96 (60h) and 160 (A0h).
<Rev. 0.6E Preliminary>
-18-
2001/11