STS1TX datasheet(7/70 Pages) STMICROELECTRONICS

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STS1TX

Introduction

A simplified block diagram of the STS1TX is shown in Figure 1.

Figure 1. STS1TX block diagram

The transmitter part of the STS1TX is based on direct synthesis of the RF frequency. The

power amplifier (PA) input is the LO generated by the RF synthesizer, while the output level

can be configured between -30 dBm and +11 dBm in 0.5 dB steps. The data to be

transmitted can be provided by an external MCU either through the 96-byte TX FIFO

writable via SPI, or directly using a programmable GPIO pin. The STS1TX supports

frequency hopping, extending the link range and improving performance.

The STS1TX has a very efficient power management (PM) system.

An integrated switched mode power supply (SMPS) regulator allows operation from a

battery voltage ranging from +1.8 V to +3.6 V, and with power conversion efficiency of at

least 80%.

A crystal must be connected between XIN and XOUT. It is digitally configurable to operate

with different crystals. As an alternative, an external clock signal can be used to feed XIN for

proper operation. The STS1TX also has an integrated low-power RC oscillator, generating

the 34.7 kHz signal used as a clock for the slowest timeouts (i.e. sleeping and backoff).

A standard 4-pin SPI bus is used to communicate with the external MCU. Four configurable

general purpose I/Os are available.

FREQ

SYNTH

REGISTERS MAP

RADIO CONTROL

RCO

ΔΔΔΔΣΣΣΣ

Low Power

Digital LDO

TEMP SENS

SDO

SDI

SCLK

CSn

GPIO_3

GPIO_2

GPIO_1

GPIO_0

VR DIG

SDN

GND PA

POR

AES

LDO

1V5

CENTRAL

BIAS

BOR

(raw)

BOR

(acc)

BLD

SMPS

DIG

I/O

1/2

GAMS080520131020FSR

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