STA8089GAT datasheet(27/33 Pages) STMICROELECTRONICS

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DS11777 Rev 4

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STA8089GAT

Electrical characteristics

Figure 3. 32.768 kHz crystal connection

To drive the 32.768 kHz crystal pins from an external clock source:



Disable the oscillator (bit28-OSCI_EN = 0b in PRCC_BACKUP_REG0 register). This

disables the internal inverter, thus reducing the power consumption to minimum.



Drive the RTC_XTI pin with a square signal or a sine wave.

4.8.3

OSCI oscillator specifications

Default supported values are 16.368 MHz, 24 MHz, 26 MHz and 48 MHz.

To enable USB peripheral the 48 MHz is mandatory

4.8.4

ADC specifications

This section gives the AC specification of the 10 bit Successive Approximation Register

ADC embedded in STA8089GAT device. It is controlled by the ARM9 MCU through a

wrapper and an APB bridge as depicted in Figure 4 and it has a maximum conversion rate

of 1MSPS with 8 muxed analog input channels capability. An internal voltage reference is

used and analog/digital power supplies connections are implemented inside the device

without any needs of dedicated external pins.

Table 23. Characteristics of external slow clock input

Symbol

Parameter

Min.

Typ.

Max.

Unit

TJIT (cc)

Cycle-to-cycle jitter

-70

—

TJIT (per)

Period jitter

-70

—

Variation

-500

—

500

ppm

TDUTY

Duty cycle

—

CL = 18 pF

32.768 kHz

Crystal

RTC_XTII

RCT_XTO

Device

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