DocID030710 Rev 1 25/31
STA8089G Electrical characteristics
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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 STA8089G 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 22. Characteristics of external slow clock input
Symbol Parameter Min. Typ. Max. Unit
T
JIT
(cc) Cycle-to-cycle jitter -70 — 70 ps
T
JIT
(per) Period jitter -70 — 70 ps
Variation -500 — 500 ppm
T
DUTY
Duty cycle 45 — 55 %
CL=18pF
CL=18pF
32.768 kHz
Crystal
RTC_XTII
RCT_XTO
Device
