IC-HT datasheet(27/45 Pages) ICHAUS

27 / 45 page

prel

imin

ary

prel

imin

ary

iC-HT

DUAL CW LASER DIODE DRIVER

Rev B1, Page 27/45

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:

• V(LDKx) up to 8 V with 8.6 mV resolution

• V(VDD) up to 8 V with 8.6 mV resolution

• V(VB) up to 8 V with 8.6 mV resolution

• V(MDAx) up to 1 V with 1.075 mV resolution

• V(PLRx) up to 1 V with 1.075 mV resolution

Note that when the value to be converted is higher than

8 V the A/D converter is saturated at its highest conver-

sion value.

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(MDA1), ADSNF1 = 0

100

Channel 1 ADC sourced by V(PLR1), ADSNF1 = 1

101

Channel 1 ADC sourced by V(VB)

110

Channel 1 ADC sourced by V(VDD)

111

Channel 1 ADC sourced by V(LDK1)

Table 54: 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(MDA2), ADSNF2 = 0

100

Channel 2 ADC sourced by V(PLR2), ADSNF2 = 1

101

Channel 2 ADC sourced by V(VB)

110

Channel 2 ADC sourced by V(VDD)

111

Channel 2 ADC sourced by V(LDK2)

Table 55: ADC channel 2 source selection

With ADCCx(2:0) = 100, the signal to the A/D con-

verter is selected by register bit ADSNFx (A/D con-

verter sense not force). With ADSNFx = 1 the mea-

suring point to the A/D converter is the internal sense

node of the internal programmable logarithmic monitor

resistor (PLR). With ADSNFx = 0 the sensing point is

connected directly to MDAx pin.

ADSNF1

Addr. 0x1A; bit 2

R/W 0

ADC measurement MDA1 pin (force)

ADC measurement PLR1 (sense)

Table 56: ADC channel 1 sense/force selection

ADSNF2

Addr. 0x1A; bit 6

R/W 0

ADC measurement MDA2 pin (force)

ADC measurement PLR2 (sense)

Table 57: ADC channel 2 sense/force selection

When enabled, the A/D converter is continuously ac-

quiring the signal selected by ADCCx register. The

conversion time, is 140 µs. Changing the source re-

quires 500 µs settling time.

In order to do a measurement, register ADCx must be

read. The converter does not provide an end of con-

version (EOC) bit. Instead, ADCx register contains al-

ways the value of the last conversion.

As the A/D converter is 10 bit long, the results are split

into two byte wide separated registers; ADCxh con-

tains channel x ADC MSBs values while ADCxl stores

the LSBs. A consecutive read action of both registers

(lower and upper part) should be carried out in order

to prevent an undesired change in the measured value

between two read actions.

ADC1

Addr. 0x03/04; bit 9:0

0x000

ADC minimum value

0x3FF

ADC maximum value

Table 58: ADC channel 1

ADC2

Addr. 0x05/06; bit 9:0

0x000

ADC minimum value

0x3FF

ADC maximum value

Table 59: ADC channel 2

The voltage corresponding to the measured digital

value can be directly obtained through the following

formula:

V (LDKx , VB, VDD) = 8 ∗ VFS

1023 ∗ ADCx

V (MDAx , PLRx ) = VFS

1023 ∗ ADCx

VFS is the fullscale voltage of the A/D converter (cf.

Electrical Characteristics No. 706) typical 1.1 V. For a

more precise measurement, the A/D converter can be

calibrated by measuring a known VB voltage and cal-

culate the VFS.

If ADSNFx = 0 the sensing point is connected directly

to MDAx pin. Depending on the regulation voltage, it

is possible that V(MDAx) is higher than 1.1 V. When

MDAx pin is the source of the A/D converter, satura-

tion of the converter will occur. When monitoring pin

MDAx with the A/D converter, V(MDAx) must be lower

than 1.1 V.

IC-HT 数据表(PDF) 27 Page - IC-Haus GmbH

IC-HT 数据表(HTML) 27 Page - IC-Haus GmbH

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

数据表下载