STR910FAZ32H6T STMICROELECTRONICS [STMicroelectronics], STR910FAZ32H6T Datasheet - Page 24

• Manufacturer Part Number: STR910FAZ32H6T
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Functional overview
3.12
3.12.1
3.12.2
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Mode. The entire chip is quiescent (except for RTC and wake-up circuitry). There are three
means to exit Sleep Mode and re-start the system:
●
●
●
Voltage supplies
The STR91xFA requires two separate operating voltage supplies. The CPU and memories
operate from a 1.65V to 2.0V on the VDD pins, and the I/O ring operates at 2.7V to 3.6V on
the VDDQ pins.
Independent A/D converter supply and reference voltage
The ADC unit on 128-pin and 144-ball packages has an isolated analog voltage supply input
at pin AVDD to accept a very clean voltage source, independent of the digital voltage
supplies. Additionally, an isolated analog supply ground connection is provided on pin AVSS
only on 128-pin and 144-ball packages for further ADC supply isolation. On 80-pin
packages, the analog voltage supply is shared with the ADC reference voltage pin (as
described next), and the analog ground is shared with the digital ground at a single point in
the STR91xFA device on pin AVSS_VSSQ.
A separate external analog reference voltage input for the ADC unit is available on 128-pin
and 144-ball packages at the AVREF pin for better accuracy on low voltage inputs. For 80-
pin packages, the ADC reference voltage is tied internally to the ADC unit supply voltage at
pin AVREF_AVDD, meaning the ADC reference voltage is fixed to the ADC unit supply
voltage.
See
AVDD, AVREF, and AVREF_AVDD.
Battery supply
An optional stand-by voltage from a battery or other source may be connected to pin VBATT
to retain the contents of SRAM in the event of a loss of the main digital supplies (V
V
VBATT pin when the voltage of V
to use the battery supply, the LVD must be enabled.
The VBATT pin also supplies power to the RTC unit, allowing the RTC to function even when
the main digital supplies (V
it is possible to select whether or not to power from VBATT only the RTC unit, or power the
RTC unit and the SRAM when the STR91xFA device is powered off.
DDQ)
Table 12: Operating
Some resets (external reset pin, low-voltage, power-up, JTAG debug command)
RTC alarm
Input from wake-up unit
. The SRAM will automatically switch its supply from the internal V
conditions, for restrictions to the relative voltage levels of VDDQ,
DD
and V
DD
drops below the LVD threshold (and not V
DDQ
) are switched off. By configuring the RTC register,
STR91xFAx32 STR91xFAx42 STR91xFAx44
DD
source to the
BAT
). In order
DD
and