LNBH26 STMicroelectronics, LNBH26 Datasheet - Page 7

• Manufacturer Part Number: LNBH26
• Description: Dual LNB supply and control IC with step-up and I2C interface
• Manufacturer: STMicroelectronics

LNBH26
2.6
2.7
2.8
output pin). In order to avoid 22 kHz waveform distortion during tone transmission, each
LNBH26 section is provided with a BPSW pin to be connected to an external transistor,
which allows the bypassing of the corresponding output RL filter in DiSEqC 2.x applications
while in transmission mode. Before starting tone transmission by means of the DSQIN pin,
provide that the TEN bit is preventively set to “1” and after ending tone transmission, provide
that the TEN bit is set to “0”.
Output current limit selection
The linear regulators 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
Equation 2
with ISET=1
(Refer also to the ISET bit description in
where RSEL is the resistor connected between ISEL and GND expressed in kΩ and
I
each channel. However, it is recommended to not exceed, for a long period, a total amount
of current of 1 A from both sections (I
overtemperature protection triggering and to thoroughly validate the PCB layout thermal
management in real application environment conditions.
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
register, write mode)
I²C bus.
Diagnostic and protection functions
The LNBH26 has 14 diagnostic internal functions provided via the I²C bus, by reading 14
bits on two STATUS registers (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 status (OTF), one bit is dedicated to the input voltage power not good
function (PNG), while the remaining 12 bits (6 per channel) are dedicated to the overload
MAX
I
I
MAX
MAX
(typ.) is the typical current limit threshold expressed in mA. I
Section 7.3: Data registers
(
(
typ
typ
.)
.)
=
=
RSEL
RSEL
16578
6452
. 1
. 1
159
206
for exact programmable values). Register writing is accessible via the
Doc ID 022771 Rev 1
and
Application information (valid for each section A/B)
Table 14: Output voltage selection table (Data1
OUT_A
Table 9
+ I
OUT_B
.)
< 1 A) in order to avoid the
MAX
can be set up to 1 A for
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