LNBS21 datasheet(4/21 Pages) STMICROELECTRONICS

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LNBS21

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Table 4: Pin Description

SYMBOL

NAME

FUNCTION

PIN NUMBER

vs. PACKAGE

VCC

Supply Input

8V to 15V supply. A 220µF bypass capacitor to

GND with a 470nF (ceramic) in parallel is

recommended

GATE

External Switch Gate

External MOS switch Gate connection of the

step-up converter

SENSE

Current Sense Input

Current Sense comparator input. Connected to

current sensing resistor

Vup

Step-up Voltage

Input of the linear post-regulator. The voltage on this

pin is monitored by internal step-ut controller to

keep a minimum dropout across the linear pass

transistor

OUT

Output Port

Output of the linear post regulator modulator to the

LNB. See truth table for voltage selections.

SDA

Serial Data

Bidirectional data from/to I2C bus.

SCL

Serial Clock

Clock from I2C bus.

DSQIN

DiSEqC Input

When the TEN bit of the System Register is LOW,

this pin will accept the DiSEqC code from the main

µcontroller. The LNBS21 will use this code to

modulate the internally generated 22kHz carrier. Set

to GND the pin if not used.

DETIN

Detector In

22kHz Tone Detector Input. Must be AC coupled to

the DiSEqC bus.

DSQOUT DiSEqC Output

Open collector output of the tone Detector to the

main

µcontroller for DiSEqC data decoding. It is

LOW when tone is detected.

EXTM

External Modulator

External Modulation Input. Need DC decoupling to

the AC source. If not used, can be left open.

GND

Ground

Pins to be connected to ground.

1, 6, 10, 11, 20

BYP

Bypass Capacitor

Needed for internal preregulator filtering

LT1

Loop Through Switch

In standby mode the power switch between LT1 and

LT2 is closed. Max allowed current is 900mA. this

pin can be left open if loop through function is not

needed.

LT2

Loop Through Switch

Same as above

ADDR

Address Setting

Four I2C bus addresses available by setting the

Address Pin level voltage

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