ST52T301 datasheet(47/100 Pages) STMICROELECTRONICS

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10.1 PWM GENERATOR WORKING MODE

When REG_CONF10 (3:2) bits, MODE, are ”01”,

the peripheral is programmed to work in PWM

Mode.

By using the 16-bit prescaler, the PWM period can

be generated by dividing the internal master clock,

or an external clock signal applied on the pin

MAIN1, or the main voltage frequency, by using the

circuit shown in Figure 10.6.

NOTE: The external clock signal, applied on

MAIN1 pin, must have a frequency at least three

time smaller than the internal master clock.

The clock source can be selected by using

REG_CONF10(5:4)bits, CKSL (see Table 10.4 and

Figure 10.9). If the clock source selected is not the

main voltage frequency(CKSL=1x), MAIN2 pin can

be configured as input or output, by using

REG_CONF10(7) bit, IOSL (see Table 10.4).

If MAIN2 is an output, on this pin it is possible to

get the prescaler output signal Tck.

The period of the PWM signal is obtained by using

the following relation:

T=256*Tck

where Tck is the output of the 16-bit prescaler

managed by REG_CONF8 and REG_CONF9 (see

Figure 10.2).

NOTE. In PWM working mode, the value N,

stored in the 16-bit prescaler, must be in the

range from 2 to 216-1

By using a 20 MHz clock master it is possible to

obtain a PWM frequency in the range 1.2 Hz to

26.04 KHz.

The value Ton is prop or tional to a value,

INIT_VALUE, that can be a fuzzy output or a value

Value

Description

PWM Driver

Burst Mode Control

(1)

Phase Angle Control

Note:

(1) REG_CONF10(5) must be set to ”1”

Table 10.1. MODE - Triac/PWM Working Mode

Settings

MCLK

Frequency

min

max

5 MHz

0.3Hz

6.51 kHz

10 MHz

0.6 Hz

13.02 kHz

20 MHz

1.2 Hz

26.04 kHz

Table 10.2. PWM Frequencies

T= 256 * Tck

Ton = INIT_VALUE* Tck

Toff

TRIACOUT

Figure 10.3. PWM Functionament

coming from Register File, according with the

I NPSL and F Z S L c onf i gu r at i on bit s of

REG_CONF12 (see Table 10.6 and Figure 10.12).

The Ton is equal to:

Ton= INIT_VALUE*Tck.

It means the Ton can be fixed by the control

algorithm that can be either the output of a fuzzy

inference or the result of an arithmetic calculus. In

the second case, the data, stored in the i-th location

of the Register File, can be loaded by using the

instruction:

LDPR 1, reg-i

If the INIT_VALUE is 255 the Toff is equal to Tck.

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ST52T301/E301

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