DocID023065 Rev 3

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LNBH29

Application information

2

Application information

This IC has a built-in DC-DC step-up converter that, from a single source from 9 V to 17.5 V,

dissipated power of 0.5 W typ. @ 500 mA load (the linear post-regulator drop voltage is

threshold (4.7 V typically). The step-up converter is provided with a soft-start function which

reduces the inrush current during startup. The SS time is internally fixed at 4 ms typ. to

switch from 0 to 13 V and 6 ms typ. to switch from 0 to 18 V.

2.1

DiSEqC™ data encoding

The LNBH29 series includes two versions with different DiSEqC control pin solutions:

LNBH29 with DSQIN pin and LNBH29E with EXTM pin.

The LNBH29 is provided with the DSQIN logic input pin (TTL compatible) to be controlled by

an external DiSEqC data envelope source which activates the internal 22 kHz tone

generator factory trimmed. This guarantees the tone output waveform in accordance with

the DiSEqC standards.

The LNBH29E is provided with the EXTM analogic modulation input pin to be connected to

an external 22 kHz DiSEqC tone source. The tone output waveform depends on the

characteristics of an external signal injected by means of the EXTM pin.

2.2

LNBH29: data encoding by external DiSEqC envelope control

through the DSQIN pin

If an external DiSEqC code 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 (see Section 5: Typical application circuits). In this way, the internal

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 of 15 µs to 60 µs after the 22

kHz TTL signal on DSQIN has expired (refer to Figure 2).

Figure 2. Tone enable and disable timing (using envelope signal)

AM10427v1

~ 6 µs

15 µs ~ 60 µs

DSQIN

Tone

Output