Mitsubishi M66242FP Datasheet

MITSUBISHI 〈DIGITAL ASSP〉

DESCRIPTION

M66242 Integrated Circuit has four 12-bit PWM (pulse width modulation) circuits which are built by using the CMOS (complementary metal oxide semiconductor) process. This IC controls PWM waveform by adjusting the “H” width according to serial data sent from MCU (micro controller unit) or other device. Each channel can be independently controlled. High-resolution digital-analog converter can be formed easily by connecting a low-pass filter circuit to the output pins of this circuit.

FEATURES

• Built-in four 12-bit high-resolution pulse width modulation circuits

• Easy digital-analog conversion – Quick output waveform smoothing Control by 1.22mV possible per step (V

CC =5V)

• Serial data input

• “H” level width setting type

• 4 independently controlled channels

• All 4 channels reset by reset input (R) High-impedance status after reset

• All 4 channels controlled by output control input (OC)

• Settings take effect after ongoing cycle is completed

• Input: TTL level

• Output: CMOS 3-state output Output current I

•V

CC =5V ± 10%

O = ±4mA

M66242P/FP

4-CH 12-BIT PWM GENERATOR

M66242P/FP

PIN CONFIGURATION (TOP VIEW)

CHIP SELECT

RESET

WRITE CONTROL

SERIAL DATA INPUT

WRITE CLOCK

OUTPUT CONTROL

CLK

GND

1 2 3 4 5 6 7

Outline

M66242P/FP

13 12 11 10

9 8

14P4

PWM1 PWM2

OUTPUT

PWM3 PWM4 X

OUT

CLOCK OUTPUT

CLOCK INPUT

14P2N-A

APPLICATION

• Analog signal control in televisions and audio systems

• Control of lamps, heaters and motors

• For software servo in home appliances and industrial machinery

BLOCK DIAGRAM (EACH CHANNEL)

Upper byte

CLK

1 3 2

Input

Lower byte

Control

circuit

To other channels

PWM

8-BIT

PWM circuit

4-bit-rate multiplier

1/2

divider

12-bit

PWM circuit

Oscillation

circuit

12 11 10

8 9 7

PWM1

PWM2 PWM3 PWM4

OUT

GND

MITSUBISHI 〈DIGITAL ASSP〉

M66242P/FP

4-CH 12-BIT PWM GENERATOR

FUNCTION

The PWM output waveform of each channel is controlled by taking in PWM data from MCU or other device via serial data

IN.

input S Twelve-bit PWM data is input being divided between upper 8 bits (upper byte) and lower 4 bits. The lower 4-bit data is combined with command data such as channel designation and input as 8-bit data (lower byte). The lower byte should be written first, and then the upper byte. Even if only the upper byte is to be changed, rewrite from the lower byte. The PWM waveform changes according to the new setting from the next cycle. One cycle of PWM waveform (4096 divisions; 12-bit resolu-

tion) are divided into 16 (2 consists of 256 (2 f

XIN**).

) subsections t. Each subsection

; 8-bit resolution) minimum bits τ (=2/

One subsection t consists of a 8-bit PWM waveform (basic waveform). The “H” width of this waveform is determined according to the upper 8 bits of PWM data. One cycle has 16

PIN DESCRIPTIONS

R CS

WR SIN

SCLK OC PWM1~PWM4

XIN

XOUT

Name

Reset input Chip select input

Write control input Serial data input

Write clock input Output control input PWM outputs 1 thru 4

Clock input

Clock output

Input/Output

Input Input

Output

Input

Output

“L”: All 4 channels put in high impedance state. “L”: Communication with MCU becomes possible. WR, SIN and SCLK put in

enable state. “L”: Serial data written.

“L”-to-“H” edge: Written data stored in upper or lower byte. Inputs 8-bit serial data from MCU synchronously with clock pulses. Inputs sync clock pulses for 8-bit serial data writing. “H”: All 4 channels put in high-impedance state. Outputs PWM waveform. (CMOS 3-state output) Inputs/outputs signals generated by clock signal generation circuit. Oscillation

frequency is determined by connecting ceramic or quartz resonator between XIN and XOUT. The frequency of internal clock (PWM timing clock) signals is the 1/2 divider of the frequency input from clock input XIN. When external clock signals are used, connect clock generator to XIN pin and leave XOUT open.

subsections t, each of which has this basic waveform. Among them, those which are designated by the 4-bit-rate multiplier are conditioned to have a “H” width that is longer by τ. The lower 4 bits of PWM data are used to specify those subsections (t

m). The waveform of other subsections remains un-

changed. A PWM waveform (12-bit resolution) is a combination of two types of waveforms which are different in “H” width, as described above. When output control input OC is “H”, the output of every channel turns high-impedance from the next cycle. When reset input R is “L”, the output of every channel turns high-impedance as soon as the ongoing cycle is completed, and PWM data of all channels is reset. If R input is changed from “L” to “H”, the next cycle starts, however, the output of the channels remains high-impedance. To enable output, rewrite input data for each channel.

XIN: Clock XIN repeat frequency

**)f

Functions

(1) Upper byte resister

b7 b6 b5 b4 b3 b2 b1 b0

MITSUBISHI 〈DIGITAL ASSP〉

M66242P/FP

4-CH 12-BIT PWM GENERATOR

(2) Lower byte resister

b7 b6 b5 b4 b3 b2 b1 b0

Fig. 1 Upper and Lower Byte Resister Makeup

PWM output “H” width setting bits

(Upper 8 bits: b11 thru b4)

Write data designation bit

0: Lower byte only 1: Both lower and upper bytes

PWM output select bit

00: PWM 1 01: PWM 2 10: PWM 3 11: PWM 4

Output control select bit

0: Output disable (Bits b7~b4 and b0 are ignored.) 1: Output enable

PWM output “H” width setting bits

(Lower 4 bits: b3 to b0)

Table 1 Mode Selection

PWM data setting

(output enable)

Mode

Lower 4-bit data setting 12-bit data setting

Output disable

b7 b6 b5 b4 1 b2 b1 0 b7 b6 b5 b4 1 b2 b1 1 XX XX0b2b1X

Lower byte data

Table 2 Patterns of Lower 4 Bits and Subsections Whose “H” Width Is Increased

PWM register

b3-b0

0000 0001 0010 0100 1000 1111

Subsections tm whose H width is

increased by τ (m =0 thru 15) Nothing m=8 m=4, 12 m=2, 6, 10, 14 m=1, 3, 5, 7, 9, 11, 13, 15 m=1~15 (m≠0)

Number of

Subsections

0 1 2 4 8

Input serial data

Upper byte data

––––

b7 b6 b5 b4 b3 b2 b1 b1

––––

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