ST52T440F3M6 STMicroelectronics, ST52T440F3M6 Datasheet - Page 65

• Manufacturer Part Number: ST52T440F3M6
• Description: MCU 8-Bit ST52 CISC 8KB EPROM 5V 20-Pin SO
• Manufacturer: STMicroelectronics

Specifications of ST52T440F3M6

• Package: 20SO
• Family Name: ST52
• Maximum Speed: 20 MHz
• Ram Size: 256 Byte
• Program Memory Size: 8 KB
• Operating Supply Voltage: 5 V
• Data Bus Width: 8 Bit
• Program Memory Type: EPROM
• Number Of Programmable I/os: 13
• On-chip Adc: 6-chx12-bit
• Operating Temperature: -40 to 85 °C
• Number Of Timers: 1

10.2 PWM Mode Settings
By using the 16-bit Prescaler (REG_CONF8 and
REG_CONF9), the PWM period can be generated
by dividing the internal master clock, an external
clock signal applied to pin MAIN1, or the mains
voltage frequency, using the circuit of Figure
10.10.
NOTE: The external clock signal applied on
MAIN1 pin must have a frequency that is at least
two times smaller than the internal master clock.
The clock source can be selected by using
REG_CONF10(4) bit, CKSL (Table 10.3).
The period T of the PWM signal Tb (see Figure
10.4) can be calculated with the following formula:
T= 255*Tck
where Tck is the period of the signal in output of
the 16-bit prescaler, according to the value stored
in REG_CONF8 and REG_CONF9 pair (Figure
10.2).
By using a 20 MHz clock master a PWM fre-
quency in the range 1.2 Hz to 78.4KHz may be
obtained (Table 10.1).
Table 10.1 PWM Frequencies
Figure 10.3 PWM Working Mode
Frequencies
10 MHz
20 MHz
MCLK
5 MHz
TRIACOUT
T b
1.2 Hz
0.6 Hz
0.3 Hz
min
Ton = INIT_VALUE* Tck
1/T
19.6 KHz
39.2 KHz
78.4 KHz
max
T = 255 * Tck
The value Ton depends on the value set by the
user in the TRIAC_COUNT Register (Output Reg-
ister 9) by using the LDPR instruction. Ton and the
corresponding duty cycle can be calculated from
the following formulas:
The TRIAC_COUNT value can be changed on fly
but it is updated only at the end of the signal
period. If TRIAC_COUNT value is 255 then Toff is
zero and TROUT signal is always equal to one
during the period T.
According to REG_CONF10(0) configuration reg-
ister bit, POL, the firing pulses polarity must be
set.
IN PWM mode, it is possible to generate a pro-
grammable Interrupt in four different ways:
1) No Interrupt;
2) Interrupt on rising edge of the signal Tb
(INT_R).
3) Interrupt on falling edge of the signal Tb
(INT_F)
4) Interrupt on both edges of the signal Tb.
The Interrupt sources described above are always
active;
REG_CONF0(5:3) bits, INTSL (see Table 4.1).
NOTE: If the Interrupt on the rising edge (INT_R)
is not masked through REG_CONF0(4), the first
Interrupt after the start occurs with a delay of a
time period T. If TRIAC_COUNT is 255 or 0, the
first interrupt after the start (either INT_R and
INT_F) occurs at time T. In any case for
TRIAC_COUNT equal to 255 or 0, INT_R and
INT_F coincide and occur at each control period T.
Duty=TRIAC_COUNT / 255
Ton=TRIAC_COUNT * Tck
they
Toff
can
ST52T400/T440/E440/T441
be
masked
through
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