C8051F902-GM Silicon Laboratories Inc, C8051F902-GM Datasheet - Page 173

• Manufacturer Part Number: C8051F902-GM
• Description: IC MCU 8BIT 8KB FLASH 24QFN
• Manufacturer: Silicon Laboratories Inc
• Series: C8051F9xxr

Specifications of C8051F902-GM

• Program Memory Type: FLASH
• Program Memory Size: 8KB (8K x 8)
• Package / Case: 24-QFN
• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 25MHz
• Connectivity: SMBus (2-Wire/I²C), SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, Temp Sensor, WDT
• Number Of I /o: 16
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 0.9 V ~ 3.6 V
• Data Converters: A/D 15x10/12b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Processor Series: C8051F9x
• Core: 8051
• Data Ram Size: 768 B
• Interface Type: UART
• Maximum Clock Frequency: 25 MHz
• Number Of Timers: 4
• Operating Supply Voltage: 0.9 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: C8051F912DK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 12 bit
• Package: 24QFN EP
• Device Core: 8051
• Family Name: C8051F90x
• Maximum Speed: 25 MHz
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 16
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 336-1848-5

18.2. Power-Fail (VDD/DC+ Supply Monitor) Reset
C8051F91x-C8051F90x devices have a VDD/DC+ Supply Monitor that is enabled and selected as a reset
source after each power-on or power-fail reset. When enabled and selected as a reset source, any power
down transition or power irregularity that causes VDD/DC+ to drop below V
be driven low and the CIP-51 will be held in a reset state (see Figure 18.3). When VDD/DC+ returns to a
level above V
After a power-fail reset, the PORSF flag reads 1, the contents of RAM invalid, and the VDD/DC+ supply
monitor is enabled and selected as a reset source. The enable state of the VDD/DC+ supply monitor and
its selection as a reset source is only altered by power-on and power-fail resets. For example, if the
VDD/DC+ supply monitor is de-selected as a reset source and disabled by software, then a software reset
is performed, the VDD/DC+ supply monitor will remain disabled and de-selected after the reset.
In battery-operated systems, the contents of RAM can be preserved near the end of the battery’s usable
life if the device is placed in Sleep Mode prior to a power-fail reset occurring. When the device is in Sleep
Mode, the power-fail reset is automatically disabled and the contents of RAM are preserved as long as the
VBAT supply does not fall below V
above V
source select state of the VDD/DC+ supply monitor are restored to the value last set by the user.
To allow software early notification that a power failure is about to occur, the VDDOK bit is cleared when
the VDD/DC+ supply falls below the V
interrupt. See Section “12. Interrupt Handler” on page 120 for more details.
Important Note: To protect the integrity of Flash contents, the VDD/DC+ supply monitor must be
enabled and selected as a reset source if software contains routines which erase or write Flash
memory. If the VDD/DC+ supply monitor is not enabled, any erase or write performed on Flash memory
will cause a Flash Error device reset.
VBAT
POR
VDD
V
V
WARN
while the user is replacing the battery. Upon waking from Sleep mode, the enable and reset
POR
RST
RST
WARN
VDDOK
SLEEP
RST
, the CIP-51 will be released from the reset state.
Power-Fail Reset
Active Mode
Figure 18.3. Power-Fail Reset Timing Diagram
POR
WARN
. A large capacitor can be used to hold the power supply voltage
VDD/DC+
VBAT
threshold. The VDDOK bit can be configured to generate an
Rev. 1.0
RAM Retained - No Reset
C8051F91x-C8051F90x
Sleep Mode
RST
will cause the RST pin to
Note: Wakeup signal
required after new
battery insertion
t
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