ST52T440F3M6 STMicroelectronics, ST52T440F3M6 Datasheet - Page 66

• 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

ST52T400/T440/E440/T441
10.3 Burst Mode
When working in Burst mode, the synchronization
with
REG_CONF10(4) bit CKSL must be set to “1”.
(Table 10.3).
A square wave Tb is generated with a duty cycle
proportional to the power the user needs to trans-
fer to the load. A pulse is generated for each zero
crossing of the mains voltage included in the Ton
of the fixed period T. Figure 10.4 illustrates the
typical Burst Control working mode. The period T
of the signal Tb (Figure 10.4) is:
The signal Tck is generated by programming the
16-bit
REG_CONF9 (Figure 10.2). Tck is equal to the
mains voltage frequency (50 or 60 Hz) divided by
N+1, where N is an integer value in the range [0,
2
The value Ton is proportional to the value con-
tained in TRIAC_COUNT Register (Output Regis-
ter 9)
The number of generated pulses N_PULSES in
TROUT pin is equal to:
where N is the value stored in the 16-bit prescaler.
Therefore it is:
The TRIAC_COUNT can be changed on fly and
takes effect from the following period; the Pres-
caler value N instead is fixed since the beginning
Figure 10.4 Burst Working Mode
66/94
16
-1].
the
N_PULSES = 2*[(N+1)*TRIAC_COUNT]
Prescaler
Ton = TRIAC_COUNT*Tck
T = 255*Tck
mains
Tb
Power
Line
-0.5
-1.5
1.5
0.5
is
-1
by
1
0
mandatory,
REG_CONF8
Ton
therefore
T = 255 * Tck
and
and cannot be changed on fly.
The first pulse is obtained during the first zero
crossing of the main voltage and the last one is
generated after clock pulses included in the time
period TRIAC_COUNT*Tck, where Tck is the
Prescaler output, generated by using the main
voltage frequency applied to MAIN1 and MAIN2
pins. This guarantees synchronization with the
mains voltage frequency.
Ranges of the Tb signal period depend on the
power line frequency and Prescaler (Table 10.2).
In order to drive a Triac in Burst Mode a pulse
sequence must be generated, which must be cen-
tered on the zero crossing of the power line as
illustrated in Figure 10.7. Therefore, the pre zero
crossing and the post zero crossing of the power
line must be detected.
To detect the zero-crossing and also obtain the
main voltage frequency, the user must generate
MAIN1 and MAIN2 signals by using the circuit
illustrated in Figure 10.5.
MAIN1 and MAIN2 signals are used in the block
called PULSE GENERATOR of the peripheral
(see Figure 10.1).
Table 10.2 TROUT Signal Period
Power Line
Frequency
50 Hz
60 Hz
5.10 s
4.25 s
min
T
334233.60 s
278528.05 s
max