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PCE84C886

Microcontroller for monitor OSD and auto-sync applications

Philips Electronics 

Philips Semiconductors

Microcontroller for monitor OSD

and auto-sync applications

Preliminary specification

PCE84C886

7 ANALOG (DC) CONTROL

The PCE84C886 has nine 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 nine PWM outputs are specified below:

• 4 PWM outputs with 6-bit resolution (PWM4 to PWM7)

• 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 PWM7 share the same pins as

Derivative Port lines DP00 to 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 and P6LVL bits in Register 23 (see

Section 12.2).

The duty cycle of outputs PWM0 to PWM7 is dependent

on the programmable contents of the data latches

(Registers 10 to 17 respectively). 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---tW-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.

8

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