IC-HT Datasheet, PDF (17/42 Pages) IC-Haus GmbH – DUAL CW LASER DIODE DRIVER

iC-HT
DUAL CW LASER DIODE DRIVER
preliminary
ACC
DCO
8 Bit
D
A
10 Bit
D
A
OVC1
RACC1
+
-
ECIE1
LDK1
N
..750mA
CI1
CIL1
CI1
..10 nF..
10 Bit
A
D
LDK1
VDD
VB
AGND1
MDA1
ADSNF1
EM C
R
8 Bit
0
LASER CHANNEL 1
APC
DISP1
255
PLR1
MRL1
Figure 6: ACC with monitor photodiode
Rev A1, Page 17/42
ECIE2
0
1
Addr. 0x15; bit 1
R/W 0
External CI capacitor for channel 2 disconnected
External CI capacitor for channel 2 connected
Table 33: Enable external capacitor channel 2
The regulator is offset compensated in order to pre-
vent optical power drifts. Offset compensation can be
disabled by setting register bit EOCx to 0.
EOC1
0
1
Addr. 0x10; bit 4
R/W 1
Channel 1 regulator offset compensation disabled
Channel 1 regulator offset compensation enabled
Table 34: Enable offset compensation channel 1
The Regulator
In MCU mode the control can be carried out without
the need of external capacitor. This allows a fast re-
sponse of the regulator. The speed of the regulator’s
response and stability can be configured using three
bits (COMPx), providing a current compensation fac-
tor.
COMP1
000
...
111
Addr. 0x13; bit 6:4
R/W 011
Minimum compensation current for the channel 1
regulator, slower response
Maximum compensation current for the channel 1
regulator, faster response
Table 30: Current compensation channel 1
EOC2
0
1
Addr. 0x15; bit 4
R/W 1
Channel 2 regulator offset compensation disabled
Channel 2 regulator offset compensation enabled
Table 35: Enable offset compensation channel 2
An internal oscillator is used for the offset compensa-
tion. A watchdog timer (WDT) is included in order to
monitor proper function of the oscillator. If an error
is detected by the WDT, the laser channels are dis-
abled, OSCERR error bit is set in STATUS0 register
and the error event is signaled at pin NCHK. This error
signaling can be suppressed using the mask register
bit MOSCERR (set to 1).
COMP2
000
...
111
Addr. 0x18; bit 6:4
R/W 011
Minimum compensation current for the channel 2
regulator, slower response
Maximum compensation current for the channel 2
regulator, faster response
MOSCERR
Addr. 0x1D; bit 0
R/W 0
0
Oscillator error (watchdog) will be signaled at
NCHK
1
Oscillator error (watchdog) will not be signaled at
NCHK
Table 36: Oscillator error mask
Table 31: Current compensation channel 2
Alternatively it is possible to use external capacitors
connected to pins CIx and CILx. In this case, register
bit ECIEx should be set to 1 and COMPx to its highest
value, "111".
ECIE1
0
1
Addr. 0x10; bit 1
R/W 0
External CI capacitor for channel 1 disconnected
External CI capacitor for channel 1 connected
Table 32: Enable external capacitor channel 1
iC-HT monitors the saturation voltage of the regula-
tor´s output transistor at pin LDKx. The LDK satura-
tion threshold can be configured through register bits
RLDKSx.
RLDKS1
00
01
10
11
Addr. 0x13; bit 3:2
R/W 00
V(LDK1) < 0.5 V sets the LDKSAT1 alarm bit
V(LDK1) < 0.8 V sets the LDKSAT1 alarm bit
V(LDK1) < 1.0 V sets the LDKSAT1 alarm bit
V(LDK1) < 1.2 V sets the LDKSAT1 alarm bit
Table 37: LDK saturation threshold selection channel
1