Application information (valid for each section

A/B)

LNBH26LS

8/33

DocID025504 Rev 1

2.3

Data encoding by external DiSEqC envelope control through

the DSQIN pin

If an external DiSEqC™ envelope source is available, the internal 22 kHz generator can be

activated during the tone transmission by connecting the DiSE

qC™ envelope source to the

DSQIN pin. In this case the I²C tone control bits must be set: EXTM=0 and TEN=1. In this

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: "Tone enable and disable

timing (using envelope signal)").

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 as per below equation:

with ISET = 0,

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

for each channel. However, do not exceed, for a long period of time, a total amount of

overtemperature protection 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 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.

2.6

Diagnostic and protection functions

The LNBH26LS has 4 diagnostic internal functions provided via the I²C bus, by reading 4

bits on the STATUS1 register (in read mode). All the diagnostic bits are, in normal

operation (that is, no failure detected), set to low. One diagnostic bit is dedicated to the

overtemperature (OTF), and two bits (one per section) are dedicated to overcurrent (OLF-

I

16578

R S E L

1.206

----------------------------

=