Application information (valid for each section A/B)

LNBH26L

6/28

Doc ID 022876 Rev 1

2.3

Data encoding by external DiSEqC envelope control through

the DSQIN pin

If an external DiSEqC envelope source is available, it is possible to use the internal 22 kHz

generator activated during the tone transmission by connecting the DiSEqC envelope

source to the DSQIN pin. In this case the I²C tone control bits must be set: EXTM=0 and

generate the LNB output 22 kHz tone. During the period in which the DSQIN is kept high the

internal control circuit activates the 22 kHz tone output.

signal rising edge, and it stops with a delay time in the range from 15 µs to 60 µs after the 22

kHz TTL signal on DSQIN has expired (refer to

Figure 3).

Figure 3.

Tone enable and disable timing (using envelope signal)

2.4

Output current limit selection

The linear regulator current limit threshold can be set by an external resistor connected to

the ISEL pin. The resistor value defines the output current limit by the equation:

Equation 1

with ISET=0,

where RSEL is the resistor connected between ISEL and GND expressed in k

each channel. However, it is recommended to not exceed for a long period a total amount of

overtemperature protection from triggering and to thoroughly validate the PCB layout

thermal management in real application environment conditions.

2.5

Output voltage selection

Each linear regulator channel output voltage level can be easily programmed in order to

accomplish application specific requirements, using 4 + 4 bits of an internal DATA1 register

(see

Section 7.3: Data registers and Table 13: Output voltage selection table (Data1

register, write mode) for exact programmable values). Register writing is accessible via the

I²C bus.

AM10427v1

~ 6 µs

15 µs ~ 60 µs

DSQIN

Tone

Output

206

.

1

MAX

RSEL

16578

.)

typ

(

I

=