IC-HT datasheet(16/42 Pages) ICHAUS

16 / 42 page

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iC-HT

DUAL CW LASER DIODE DRIVER

Rev A1, Page 16/42

EACC2

Addr. 0x15; bit 0

R/W 0

APC mode enabled for channel 2

ACC mode enabled for channel 2

Table 23: APC/ACC in channel 2

In ACC mode the internal programmable logarithmic

monitor resistor (PLR) is not used. Instead the inter-

nal RACCx resistor is used set the current. Figure 5

shows an example of this conﬁguration.

Two different current ranges can be set through regis-

ter bit RACCx, with RACCx = 1 for up to 90 mA and

with RACCx = 0 for up to 750 mA (cf. Electrical Char-

acteristics No. 114).

10 Bit

ACC

APC

RACC

PLR1

..10 nF..

255

8 Bit

LASER CHANNEL 1

10 Bit

..750mA

CI1

8 Bit

MRL1

MDA1

AGND1

CIL1

CI1

LDK1

DCO

ECIE1

VDD

LDK1

ADSNF1

OVC

DISP1

EMC

..750mA

CI1

Figure 5: ACC mode simpliﬁed

RACC1

Addr. 0x1A; bit 0

R/W 0

Current range high for channel 1

Current range low for channel 1

Table 24: RACC1 conﬁguration

RACC2

Addr. 0x1A; bit 4

R/W 0

Current range high for channel 2

Current range low for channel 2

Table 25: RACC2 conﬁguration

In each range, the particular overcurrent threshold

value can be set in register ILIMx.

ILIM1

Addr. 0x11; bit 7:0

R/W 0xFF

0x00

Channel 1 overcurrent threshold set to minimum

current

. . .

Channel 1 overcurrent threshold set to

Ilim = (∆I(LDK ) · n), n from 0 to 255

0xFF

Channel 1 overcurrent threshold set to maximum

current

Table 26: Overcurrent threshold conﬁguration channel

ILIM2

Addr. 0x16; bit 7:0

R/W 0xFF

0x00

Channel 2 overcurrent threshold set to minimum

current

. . .

Channel 2 overcurrent threshold set to

Ilim = (∆I(LDK ) · n), n from 0 to 255

0xFF

Channel 2 overcurrent threshold set to maximum

current

Table 27: Overcurrent threshold conﬁguration channel

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 disabled.

The overcurrent error will remain

forced until SOVCx = 0.

SOVC1

Addr. 0x1D; bit 5

R/W 0

No overcurrent event at channel 1 is simulated.

Overcurrent event at channel 1 simulated.

Table 28: Simulate overcurrent channel 1

SOVC2

Addr. 0x1D; bit 6

R/W 0

No overcurrent event at channel 2 is simulated.

Overcurrent event at channel 2 simulated.

Table 29: Simulate overcurrent channel 2

In ACC mode, the MDAx pin can be monitored through

a 10 bit A/D converter. This can be used for measur-

ing the laser light power, if a photodiode is connected

to pin MDAx, as it is shown in ﬁgure 6. This allows ad-

justing the voltage reference in order to set the laser

current and obtain the desired laser light power.

The internal programmable logarithmic monitor Resis-

tor (PLR), if enabled (DISPx = 0), gives feedback for

the current control through the 10 bit A/D converter.

sure the internal sense node.

An external monitor

resistor can be used to measure the optical power,

achieved by setting DISPx to 1. Therefore register bit

ADSNFx must be set to 0 in order to measure directly

at pin MDAx.

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