IC-HTP Datasheet, PDF (30/51 Pages) IC-Haus GmbH – DUAL CW P-TYPE LASER DIODE DRIVER

iC-HTP
DUAL CW P-TYPE
LASER
DIODE
DRIVER
preliminary
Rev B1, Page 30/51
10 BIT LINEAR A/D CONVERTER
A 10 bit linear A/D converter is available for each chan-
nel when working in MCU mode. A variety of voltages
can be measured by the converter with two resolutions:
ADFNS1
0
1
Addr. 0x1A; bit 2
R/W 0
ADC measurement PLR1 after level shifting (sense)
ADC measurement MDK1 pad (force)
• V(LDAx) up to 11 V with 11.81 mV resolution
• V(VDD) up to 8 V with 8.6 mV resolution
• V(VB) up to 11 V with 11.81 mV resolution
• V(VBLx) up to 11 V with 11.81 mV resolution
• V(MDKx) up to 1.1 V with 1.075 mV resolution
• V(RACC) up to 1.1 V with 1.075 mV resolution
• V(PLRx) up to 1.1 V with 1.075 mV resolution
The register bits ADCCx select the signal measured
with the 10 bit A/D converter.
ADCC1(2:0)
Addr. 0x10; bit 7:5
R/W 000
0xx
Channel 1 ADC disabled
100
Channel 1 ADC sourced by V(MDK1), ADFNS1 = 1,
CMES1 = 0
100
Channel 1 ADC sourced by V(PLR1), ADFNS1 = 0,
CMES1 = 0
100
Channel 1 ADC sourced by ACC current sensor,
CMES1 = 1
101
Channel 1 ADC sourced by V(VB)
110
Channel 1 ADC sourced by V(VBL1)
111
Channel 1 ADC sourced by V(LDA1)
Table 63: ADC channel 1 source selection
ADCC2(2:0)
Addr. 0x15; bit 7:5
R/W 000
0xx
Channel 2 ADC disabled
100
Channel 2 ADC sourced by V(MDK2), ADFNS2 = 1,
CMES2 = 0
100
Channel 2 ADC sourced by V(PLR2), ADFNS2 = 0,
CMES2 = 0
100
Channel 2 ADC sourced by ACC current sensor,
CMES2 = 1
101
Channel 2 ADC sourced by V(VDD)
110
Channel 2 ADC sourced by V(VBL2)
111
Channel 2 ADC sourced by V(LDA2)
Table 64: ADC channel 2 source selection
Table 65: ADC channel 1 force/sense selection
ADFNS2
0
1
Addr. 0x1A; bit 6
R/W 0
ADC measurement PLR2 after level shifting (sense)
ADC measurement MDK2 pad (force)
Table 66: ADC channel 2 force/sense selection
With the CMESx bit, the ADC can be used for laser
current measurement in ACC mode. For this measure-
ment, ADCCx register must be set to 100. As shown in
figure 7, a fraction of the current delivered by the driver
to the laser is mirrored to a resistor. The voltage drop
at this resistor is sourced to the ADC. For a given value
of the ADC, the current can be calculated as follows
I(LDAx)
=
VFS
1023
∗ADCx
R
∗ MFACT
VFS is the fullscale voltage of the A/D converter (cf.
Electrical Characteristics No. 706) typical 1.1 V. MFACT
is the Mirror factor between the LDA driver and the mea-
surement. This Factor is dependent on the selected
current range (CRNG(1:0)), see table below:
ACC mirror factor
MERGE CRNGx
0
00
0
01
0
10
0
11
1
00
1
01
1
10
1
11
Mirror factor
Mirror Factor set to 2500
Mirror Factor set to 333
Mirror Factor set to 83
Mirror Factor set to 30
Mirror Factor set to 5000
Mirror Factor set to 666
Mirror Factor set to 166
Mirror Factor set to 60
Table 67: Mirror factor
R is the value of the measurement resistance, this value
is dependent on RACC bit, see table below:
With ADCCx(2:0) = 100, the signal to the A/D converter
is selected by register bit ADFNSx (A/D converter force
not sense). With ADFNSx = 0 the measuring point to the
A/D converter is the internal sense node of the internal
programmable logarithmic monitor resistor (PLR). With
ADFNSx = 1 the sensing point is connected directly to
MDKx pin.
RACC1
0
1
Addr. 0x1A; bit 0
R/W 0
Current range high for channel 1, Current sensor
resistor (Rsensex) set to 2kΩ
Current range low for channel 1, Current sensor
resistor (Rsensex) set to 16kΩ
Table 68: Current range configuration channel 1