ST72T331N2T6 STMicroelectronics, ST72T331N2T6 Datasheet - Page 18

• Manufacturer Part Number: ST72T331N2T6
• Description: 8-bit Microcontrollers - MCU OTP EPROM 8K SPI/SCI
• Manufacturer: STMicroelectronics

Specifications of ST72T331N2T6

• Product Category: 8-bit Microcontrollers - MCU
• Rohs: yes
• Core: ST7
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 16 MHz
• Program Memory Size: 8 KB
• Data Ram Size: 384 B
• On-chip Adc: Yes
• Package / Case: TQFP-64
• Mounting Style: SMD/SMT
• A/d Bit Size: 8 bit
• A/d Channels Available: 8
• Interface Type: SCI, SPI
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Number Of Programmable I/os: 44
• Number Of Timers: 2
• On-chip Dac: No
• Program Memory Type: EPROM
• Factory Pack Quantity: 90
• Supply Voltage - Max: 5.5 V
• Supply Voltage - Min: 3.5 V

ST72E331 ST72T331
3 CLOCKS, RESET, INTERRUPTS & POWER SAVING MODES
3.1 CLOCK SYSTEM
3.1.1 General Description
The MCU accepts either a crystal or ceramic reso-
nator, or an external clock signal to drive the inter-
nal oscillator. The internal clock (f
from the external oscillator frequency (f
external Oscillator clock is first divided by 2, and
an additional division factor of 2, 4, 8, or 16 can be
applied, in Slow Mode, to reduce the frequency of
the f
chip peripherals. The CPU clock signal consists of
a square wave with a duty cycle of 50%.
The internal oscillator is designed to operate with
an AT-cut parallel resonant quartz crystal resona-
tor in the frequency range specified for f
circuit shown in
using a crystal, and
ed capacitance and feedback resistance values.
The crystal and associated components should be
mounted as close as possible to the input pins in
order to minimize output distortion and start-up
stabilisation time.
Use of an external CMOS oscillator is recom-
mended when crystals outside the specified fre-
quency ranges are to be used.
3.1.2 External Clock
An external clock may be applied to the OSCIN in-
put with the OSCOUT pin not connected, as
shown on
Table 5 Recommended Values for 16 MHz
R
crystal (upper limit).
C
tal (upper limit 7pF).
C
pins OSCIN and OSCOUT (the value includes the
external capacitance tied to the pin plus the para-
sitic capacitance of the board and of the device).
18/107
18
SMAX
0
OSCOUT
C
: Parasitic shunt capacitance of the quartz crys-
C
R
OSCOUT
CPU
OSCIN
SMAX
: Parasitic series resistance of the quartz
; this clock signal is also routed to the on-
, C
Crystal Resonator (C
Figure
OSCIN
56pF
56pF
Figure 11
40
10.
: Maximum total capacitance on
Table 5
is recommended when
lists the recommend-
47pF
47pF
60
0
< 7pF)
CPU
) is derived
OSC
150
22pF
22pF
osc
)
. The
.
The
Figure 10. External Clock Source Connections
Figure 11. Crystal/Ceramic Resonator
Figure 12. Clock Prescaler Block Diagram
C
OSCIN
OSCIN
C
OSCIN
OSCOUT
EXTERNAL
OSCIN
CLOCK
OSCIN
C
OSCOUT
%2
OSCOUT
OSCOUT
NC
% 2, 4, 8, 16
C
OSCOUT
f
to CPU and
Peripherals
CPU