IC-HTP datasheet(19/51 Pages) ICHAUS

19 / 51 page

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iC-HTP

DUAL CW P-TYPE LASER DIODE DRIVER

Rev B1, Page 19/51

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.

Rsensex is 2kΩ when RACCx = 0 or 16kΩ when

RACCx = 1

MFACTx depends on several parameters as stated in

the following table:

ACC mirror factor

MERGE

CRNGx

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 33: Mirror factor

Table 34 shows some typical current settings. For de-

tailed limits, please refer to Electrical Characteristics

No. 114

ACC typical current settings

CRNG(1:0) REFx

RACCx=0 RACCx=1

0x000

125.3 mA

15.66 mA

0x001

125.6 mA

15.70 mA

0x010

125.9 mA

15.73 mA

...

0x200

416.6 mA

52.08 mA

0x201

417.6 mA

52.20 mA

0x202

418.6 mA

52.33 mA

...

0x3FD

1376.1 mA 172.01 mA

0x3FE

1379.3 mA 172.41 mA

0x3FF

1382.6 mA 172.82 mA

Table 34: ACC typical current settings

In ACC mode, the MDKx pin can be monitored through

a 10 bit A/D converter from 0 V up to 1.1 V. This can be

used for measuring the laser light power, if a photodi-

ode is connected to pin MDKx, as it is shown in figure 8.

This allows adjusting the voltage reference in order to

set the laser current and obtain the desired laser light

power.

The internal programmable logarithmic monitor Resistor

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

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

ister bit ADFNSx must be set to 0 in order to measure

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 ADFNSx must

be set to 1 in order to measure directly at pin MDKx.

Signal Level Converter

255

10 Bit

ACC

ADMDK1

LASER CHANNEL 1

8 Bit

..10 nF..

APC

8 Bit

I LDA1

CI1

ECIE1

DCO

LDA1

OVC

CIH1

VBL1

ADFNS1

LDA1

VBL1

VDD

EMC

DISP1

MDK1

MRH1

I LDA1

CI1

Figure 8: ACC with monitor photodiode

ACC mode permits combining both channels in one

iC-HTP (see chapter COMBINING BOTH CHANNELS)

and several iC-HTP in parallel. When both channels

are combined the programmable overcurrent shutdown

is carried out per each channel. If both channels are

configured in ACC mode, LDA1 and LDA2 can be con-

nected together. Each channel can be configured with

a different current range, yielding different granularity

in steps regulation for each channel.

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 factor.

COMP1

Addr. 0x13; bit 6:4

R/W 011

000

Minimum compensation current for the channel 1

regulator, slower response

. . .

111

Maximum compensation current for the channel 1

regulator, faster response

Table 35: Current compensation channel 1

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