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PCE84C882

Microcontroller for monitor OSD and auto-sync applications

Philips Electronics 

Philips Semiconductors

Microcontroller for monitor OSD

and auto-sync applications

Preliminary specification

PCE84C882

7 ANALOG (DC) CONTROL

The PCE84C882 has eight Pulse Width Modulated (PWM)

outputs for analog control purposes e.g. brightness,

contrast, H-shift, V-shift, H-width, V-size, E-W, R (or G or

B) gain control etc. Each PWM output generates a pulse

pattern with a programmable duty cycle.

The eight PWM outputs are specified below:

• 3 PWM outputs with 6-bit resolution (PWM4, 6 and 7)

• 4 PWM outputs with 7-bit resolution (PWM0 to PWM3)

• 1 PWM output with 14-bit resolution (PWM8).

The 6 and 7-bit PWM outputs are described in Section 7.1;

the 14-bit PWM output is described in Section 7.2 and a

typical PWM output application is described in Section 7.3.

7.1 6 and 7-bit PWM outputs

PWM outputs PWM0 to PWM4, PWM6 and PWM7, share

the same pins as Derivative Port lines DP00 to DP04,

DP06 and DP07, respectively. Selection of the pin function

as either a PWM output or a Derivative Port line is

achieved using the appropriate PWMnE bit in Register 21

(see Table 38).

The polarity of the PWM outputs is programmable and is

selected by the P7LVL or the P6LVL bit in Register 23

(see Section 12.2). The state of the P7LVL bit determines

the polarity of the 7-bit PWMs; the state of the P6LVL bit

determines the polarity of the 6-bit PWMs.

The duty cycle of each PWM output is dependent upon the

programmable contents of its associated data latch

(Registers 10 to 17 respectively, Register 15 is not used

as there is no PWM5 output). As the clock frequency of

each PWM circuit is 1⁄3 × fxtal, the pulse width of the pulse

generated can be calculated as shown below.

Pulse width = -3----×------(--f-P-x--t-W-a--l--M-----n----)-

Where (PWMn) is the decimal value held in the data latch.

The maximum repetition frequency (fPWM) of the 6 and

7-bit PWM outputs is shown below.

For the 6-bit PWM outputs: fPWM = 1-f--x-9-t-a-2--l

For the 7-bit PWM outputs: fPWM = 3-f--x-8-t-a-4--l

The block diagram for the 6 and 7-bit PWM outputs is

shown in Fig.5.

handbook, full pagewidth

f xtal

3

internal data bus

6 or 7-BIT PWM DATA LATCH

P6LVL/P7LVL

DP0x data

I/O

PWMnE

Q

6 or 7-BIT DAC PWM

CONTROLLER

Q

DP0x/PWMx

MLC069

1996 Jan 08

Fig.5 Block diagram for 6 and 7-bit PWMs.

9

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