ST72F621J4T1 STMicroelectronics, ST72F621J4T1 Datasheet - Page 30

• Manufacturer Part Number: ST72F621J4T1
• Description: IC MCU 8BIT LS 16K 44-TQFP
• Manufacturer: STMicroelectronics
• Series: ST7r

Specifications of ST72F621J4T1

• Core Processor: ST7
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SCI, SPI, USB
• Peripherals: DMA, LVD, POR, PWM, WDT
• Number Of I /o: 31
• Program Memory Size: 16KB (16K x 8)
• Program Memory Type: FLASH
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 44-TQFP, 44-VQFP
• Processor Series: ST72F6x
• Core: ST7
• Data Bus Width: 8 bit
• Data Ram Size: 768 B
• Interface Type: SCI, SPI, USB
• Maximum Clock Frequency: 12 MHz
• Number Of Programmable I/os: 31
• Number Of Timers: 2
• Maximum Operating Temperature: + 70 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: 0 C
• On-chip Adc: 10 bit, 8 Channel
• For Use With: 497-5046 - KIT TOOL FOR ST7/UPSD/STR7 MCU
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details
• Other names: 497-2111

ST7262xxx
8 POWER SAVING MODES
8.1 INTRODUCTION
There are three Power Saving modes. Slow Mode
is selected by setting the SMS bits in the Miscella-
neous register. Wait and Halt modes may be en-
tered using the WFI and HALT instructions.
After a RESET the normal operating mode is se-
lected by default (RUN mode). This mode drives
the device (CPU and embedded peripherals) by
means of a master clock which is based on the
main oscillator frequency divided by 3 and multi-
plied by 2 (f
From Run mode, the different power saving
modes may be selected by setting the relevant
register bits or by calling the specific ST7 software
instruction whose action depends on the oscillator
status.
8.1.1 Slow Mode
In Slow mode, the oscillator frequency can be di-
vided by a value defined in the Miscellaneous
Register. The CPU and peripherals are clocked at
this lower frequency. Slow mode is used to reduce
power consumption, and enables the user to adapt
clock frequency to available supply voltage.
8.2 WAIT MODE
WAIT mode places the MCU in a low power con-
sumption mode by stopping the CPU.
This power saving mode is selected by calling the
“WFI” ST7 software instruction.
All peripherals remain active. During WAIT mode,
the I bit of the CC register is forced to 0, to enable
all interrupts. All other registers and memory re-
main unchanged. The MCU remains in WAIT
mode until an interrupt or Reset occurs, whereup-
on the Program Counter branches to the starting
address of the interrupt or Reset service routine.
The MCU will remain in WAIT mode until a Reset
or an Interrupt occurs, causing it to wake up.
Refer to
30/139
Figure
CPU
).
24.
Doc ID 6996 Rev 5
Figure 24. WAIT Mode Flow Chart
Note: Before servicing an interrupt, the CC register is
pushed on the stack. The I-Bit is set during the inter-
rupt routine and cleared when the CC register is
popped.
N
INTERRUPT
Y
OSCILLATOR
PERIPH. CLOCK
CPU CLOCK
I-BIT
N
OR SERVICE INTERRUPT
OSCILLATOR
PERIPH. CLOCK
CPU CLOCK
FETCH RESET VECTOR
I-BIT
WFI INSTRUCTION
CYCLES DELAY
514 CPU CLOCK
IF RESET
RESET
Y
ON
ON
OFF
CLEARED
ON
ON
ON
SET