IC-HTP Datasheet, PDF (29/51 Pages) IC-Haus GmbH – DUAL CW P-TYPE LASER DIODE DRIVER

iC-HTP
DUAL CW P-TYPE
LASER
DIODE
DRIVER
preliminary
Rev B1, Page 29/51
8 Bit
D
A
10 Bit
D
A
DCO
VB
VBL1
CIH1
+
ECIE1
CI1
CI1
-
CI
LDA1
..10 nF..
VDD
I LDA1
MRH1
EM C
8 Bit
DISP1
R
0
255
10 Bit
A
D
LDA1
VBL1
VB
A DM DK 1
LASER CHANNEL 1 ^ADFNS1
x1
x2
Signal Level Converter
APC
MDK1
RM1
P
Figure 16: PLR in APC
In ACC mode the PLR is not used in the control cir-
cuit. Instead, the internal RACCx resistor is used in the
control loop.
Register bit ADFNSx is set to 0 to measure the internal
sense node. Alternatively, an external monitor resistor
can be used to measure the optical power, by setting
DISPx to 1. Then register bit ADFNSx must be set to 1
in order to measure directly at pin MDKx.
10 Bit
D
A
8 Bit
D
A
+
-
CI
OVC
ECIE1
DCO
VBL1
CIH1
CI1
LDA1
ACC
VDD
MRH1
VB
CI1
..10 nF..
I LDA1
EM C
8 Bit
DISP1
R
0
255
APC
MDK1
x1
LDA1
P
10 Bit
A
D
VBL1
VB
A DM DK 1
x2
LASER CHANNEL 1 ^ADFNS1
Signal Level Converter
Even though the PLR is not in the control circuit, it
can be enabled (DISPx = 0) in order to give feedback
through the 10 bit A/D converter for the controlling light
power if a monitor diode is connected.
Figure 17: ACC with monitor photodiode
10 BIT LOGARITHMIC D/A CONVERTER
The 10 bit logarithmic D/A converter is used for setting
the regulator´s voltage reference. The D/A converter is
active in all operating modes. In iC-WK mode only two
values are available: 0.25 V (setting INS/WKR pin lo)
and 0.5 V (setting INS/WKR pin hi). In MCU mode both
APC and ACC use the D/A converter. With a range
from 0.1 V to 1.1 V and the typical step width is 0.235%.
The D/A converter is configured through register
REFx(9:0). With REFx(9:0) = 0x000, D/A output value
is set to 0.1 V, and for REFx(9:0) = 0x3FF, D/A output is
configured to 1.1 V.
REF2
0x000
...
0x3FF
Addr. 0x18/19; bit 9:0
R/W 0x000
Channel 2 regulator reference voltage set to
minimum voltage
Channel 2 regulator reference voltage set to
Vref
=
Vref₀(1
+
∆
Vref (%)
100
)ⁿ
+
1
,
n
from
0
to
1023
Channel 2 regulator reference voltage set to
maximum voltage
Table 62: Regulator voltage reference channel 2
To calculate the D/A converter value for each REFx
value, use the following expression:
REF1
0x000
...
0x3FF
Addr. 0x13/14; bit 9:0
R/W 0x000
Channel 1 regulator reference voltage set to
minimum voltage
Channel 1 regulator reference voltage set to
Vref
=
Vref₀(1
+
∆
Vref (%)
100
)^{n +}
1
,
n
from
0
to
1023
Channel 1 regulator reference voltage set to
maximum voltage
Vref
=
Vref₀(1
+
∆
Vref (%)
100
)ⁿ
+1
,
n
from
0
to
1023
Where Vref₀ is the minimum value (typically 0.1 V),
∆ Vref (%) is the step value (typically 0.235 %) and n is
the value of REFx register in decimal.
Table 61: Regulator voltage reference channel 1