ST7FDALI 查看數據表（PDF） - STMicroelectronics

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ST7FDALI

8-BIT MCU WITH SINGLE VOLTAGE FLASH MEMORY, DATA EEPROM, ADC, TIMERS, SPI, DALI

STMicroelectronics 

ST7DALI

7 SUPPLY, RESET AND CLOCK MANAGEMENT

The device includes a range of utility features for

securing the application in critical situations (for

example in case of a power brown-out), and re-

ducing the number of external components.

Main features

■ Clock Management

– 1 MHz internal RC oscillator (enabled by op-

tion byte)

– 1 to 16 MHz or 32kHz External crystal/ceramic

resonator (selected by option byte)

– External Clock Input (enabled by option byte)

– PLL for multiplying the frequency by 8 or 4

(enabled by option byte)

– For clock ART counter only: PLL32 for multi-

plying the 8 MHz frequency by 4 (enabled by

option byte). The 8 MHz input frequency is

mandatory and can be obtained in the follow-

ing ways:

–1 MHz RC + PLLx8

–16 MHz external clock (internally divided

by 2)

–2 MHz. external clock (internally divided by

2) + PLLx8

–Crystal oscillator with 16 MHz output fre-

quency (internally divided by 2)

■ Reset Sequence Manager (RSM)

■ System Integrity Management (SI)

– Main supply Low voltage detection (LVD) with

reset generation (enabled by option byte)

– Auxiliary Voltage detector (AVD) with interrupt

capability for monitoring the main supply (en-

abled by option byte)

7.1 INTERNAL RC OSCILLATOR ADJUSTMENT

The device contains an internal RC oscillator with

an accuracy of 1% for a given device, temperature

and voltage range (4.5V-5.5V). It must be calibrat-

ed to obtain the frequency required in the applica-

tion. This is done by software writing a calibration

value in the RCCR (RC Control Register).

Whenever the microcontroller is reset, the RCCR

returns to its default value (FFh), i.e. each time the

device is reset, the calibration value must be load-

ed in the RCCR. Predefined calibration values are

stored in EEPROM for 3 and 5V VDD supply volt-

ages at 25°C, as shown in the following table.

RCCR

RCCR0

RCCR1

Conditions

VDD=5V

TA=25°C

fRC=1MHz

VDD=3V

TA=25°C

fRC=700KHz

ST7DALI

Address

1000h

and FFDEh

1001h

and FFDFh

Note:

– See “ELECTRICAL CHARACTERISTICS” on

page 100. for more information on the frequency

and accuracy of the RC oscillator.

– To improve clock stability, it is recommended to

place a decoupling capacitor between the VDD

and VSS pins.

– These two bytes are systematically programmed

by ST, including on FASTROM devices. Conse-

quently, customers intending to use FASTROM

service must not use these two bytes.

– RCCR0 and RCCR1 calibration values will be

erased if the read-out protection bit is reset after

it has been set. See “Read out Protection” on

page 14.

Caution: If the voltage or temperature conditions

change in the application, the frequency may need

to be recalibrated.

Refer to application note AN1324 for information

on how to calibrate the RC frequency using an ex-

ternal reference signal.

7.2 PHASE LOCKED LOOP

The PLL can be used to multiply a 1MHz frequen-

cy from the RC oscillator or the external clock by 4

or 8 to obtain fOSC of 4 or 8 MHz. The PLL is ena-

bled and the multiplication factor of 4 or 8 is select-

ed by 2 option bits.

– The x4 PLL is intended for operation with VDD in

the 2.4V to 3.3V range

– The x8 PLL is intended for operation with VDD in

the 3.3V to 5.5V range

Refer to Section 15.1 for the option byte descrip-

tion.

If the PLL is disabled and the RC oscillator is ena-

bled, then fOSC = 1MHz.

If both the RC oscillator and the PLL are disabled,

fOSC is driven by the external clock.

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