IC-HTP Datasheet, PDF (18/51 Pages) IC-Haus GmbH – DUAL CW P-TYPE LASER DIODE DRIVER

iC-HTP
DUAL CW P-TYPE
LASER
DIODE
DRIVER
preliminary
Rev B1, Page 18/51
ACC Current Ranges
CRNGx(1:0) RACCx
00
0
01
0
00
1
10
0
01
1
11
0
10
1
11
1
Idc(LDA)
750 mA
100 mA
90 mA
25 mA
12 mA
9 mA
3 mA
1.1 mA
Table 28: ACC current ranges
For fine-tuning the regulated current, the reference volt-
age can be set with a 10 bit logarithmic D/A converter,
which is configurable through the register REFx. This
converter has a voltage range that goes typically from
0.1 V to 1.1 V, allowing an operation resolution of typi-
cally 0.235%. More information on the logarithmic D/A
converter can be found on page 29.
ILIM1
0x00
...
0xFF
Addr. 0x11; bit 7:0
R/W 0xFF
Channel 1 overcurrent threshold set to the minimum
current in APC mode (EACC1 = 0) or overcurrent
protection disabled in ACC mode (EACC1 = 1)
Channel 1 overcurrent threshold set to
Ilim = (∆I(LDA), max · n · k), n from 0 to 255
Channel 1 overcurrent threshold set to the maximum
current
Table 29: Overcurrent threshold configuration
channel 1
ILIM2
0x00
...
0xFF
Addr. 0x16; bit 7:0
R/W 0xFF
Channel 2 overcurrent threshold set to the minimum
current in APC mode (EACC2 = 0) or overcurrent
protection disabled in ACC mode (EACC2 = 1)
Channel 2 overcurrent threshold set to
Ilim = (∆I(LDA), max · n · k), n from 0 to 255
Channel 2 overcurrent threshold set to the maximum
current
Table 30: Overcurrent threshold configuration
channel 2
A programmable overcurrent threshold is available in
order to protect the laser diode during the power-on
instant. The overcurrent protection value, Ilim, must be
configured in the 8 bit register ILIMx using the following
equations:
An overcurrent event can be simulated using bit SOVCx.
If SOVCx = 1, the corresponding overcurrent error bit
OVCx will be set to 1, the error will be signaled through
NCHK and the corresponding laser channel will be dis-
abled. The overcurrent error will remain forced until
SOVCx = 0.
Ilim = (∆I(LDA), max) · n · k
SOVC1
0
1
Addr. 0x1D; bit 5
R/W 0
No Overcurrent event at channel 1 is simulated
Overcurrent event at channel 1 simulated
Table 31: Simulate overcurrent channel 1
Ilim
n = _{k · ∆I(LDA), max}
SOVC2
0
1
Addr. 0x1D; bit 6
R/W 0
No overcurrent event at channel 2 is simulated
Overcurrent event at channel 2 simulated
Table 32: Simulate overcurrent channel 2
with n from 0 to 255.
If ILIM is set to 0 in ACC mode, the overcurrent protec-
tion is disconnected.
Calculating the expected output current in ACC
mode
∆I(LDA), max is the shutdown current threshold reso-
lution (maximum value) (cf. Electrical Characteristics
No. 108). Its value depend on the current range de-
fined by register bit RACCx. If RACCx = 1, the over-
current threshold is in the low range and ∆I(LDA), max
= 0.375 mA. If RACCx = 0, the overcurrent threshold
is in the high range and ∆I(LDA), max = 3 mA. k is
a current range factor, with a value depending on
CRNGx(1:0) register
The following formula can be used to estimate the ex-
pected current value for an ACC configuration. The
resulting value is a typical value.
Ilaser (typ)
=
Vrefx
Rsensex
· MFACTx
Where
Vrefx
=
Vref₀(1 +
∆
Vref (%)
100
)ⁿ
+
1_,
n
from
0
to
1023