LNBS21PD(2002) 查看數據表（PDF） - STMicroelectronics

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LNBS21PD
(Rev.:2002)

LNB SUPPLY AND CONTROL IC WITH STEP-UP CONVERTER AND I2C INTERFACE

STMicroelectronics 

LNBS21

TABLE A: PIN CONFIGURATIONS

SYMBOL

NAME

VCC Supply Input

GATE Exrernal Switch Gate

SENSE Current Sense Input

Vup Step-up Voltage

OUT Output Port

SDA Serial Data

SCL Serial Clock

DSQIN DiSEqC Input

DETIN Detector In

DSQOUT DiSEqC Output

EXTM Extrernal Modulator

GND Ground

BYP Bypass Capacitor

LT1 Loop Through Switch

LT2 Loop Through Switch

ADDR Address Setting

FUNCTION

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

GND with a 470nF (ceramic) in parallel is

recommended

External MOS switch Gate connection of the

step-up converter

Current Sense comparator input. Connected to

current sensing resistor

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

Output of the linear post regulator modulator to the

LNB. See truth table for voltage selections.

Bidirectional data from/to I2C bus.

Clock from I2C bus.

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 thi pin if not used.

22kHz Tone Detector Input. Must be AC coupled to

the DiSEcQ bus.

Open collector output of the tone Detector to the

main µcontroller for DiSEcQ data decoding. It is

LOW when tone is detected.

External Modulation Input. Need DC decoupling to

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

Circuit Ground. It is internally connected to the die

frame for heat dissipation.

Needed for internal preregulator filtering

In standby mode the power switch between LT1

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

this pin can be left open if loopthrough function is

not needed.

Same as above

Four I2C bus addresses available by setting the

Address Pin level voltage

PIN NUMBER

vs PACKAGE

18

17

16

19

2

12

13

14

9

15

5

1, 10, 11, 20

8

4

3

7

4/19

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