STB5701 datasheet(23/35 Pages) STMICROELECTRONICS

23 / 35 page

STB5701

Functional description

23/35

4.3.4

Min /Max peak detector

The peak detector embedded in the STB5701, in conjunction with an external RC filter

(PINs 22, 23, 24), generates a DC output voltage equal to the mean of the min and max

peak value of the data signal. The resistor provides a path for the capacitor to discharge,

allowing the peak detector to dynamically follow peak changes of the data filter output

voltage.

4.3.5

Data slicer

The purpose of the data slicer is to take the analog output of the data filter and convert it to

a digital signal. This is achieved by using a comparator and comparing the analog input to a

threshold voltage. One input is supplied by the data filter output.

The other path is fed to the min/max Peak detector to derive the average value (DC

component) as an adaptive slice reference which is presented to the positive comparator

input. The adaptive reference allows detecting the received data over a large range of noise

floor levels.

4.4

Digital control and source selection

Figure 7.

Digital section block diagram

The STB5701 digital section is responsible for the following functions:

●

Configuration of the RF front end through software programmable config bits.

●

Configuration of the PLL through software programmable registers (PLLA,M,R).

●

Detection of a pre-programmed start code sequence (one of two possibilities).

●

Arbitration between UHF and IR sources.

The serial data emerges from the DATA output pin (PIN 17) and the system state emerges

from the STATE output pin (PIN 14).

I2C

Interface

Data Slicer

SCD

Digital

Section

Test_EN

Pin 28

SAD

Pin 25

Clk

DOUT (17)

notReset

SCL

(12)

SDA

(13)

IR_IN

(15)

Vcc_Dig

(16)

STATE

(14)

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