M38B74FD datasheet(62/110 Pages) RENESAS

62 / 110 page

38B7 Group

SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS

D-A CONVERTER

The 38B7 group has one internal D-A converter with 8-bit resolu-

tion.

The D-A conversion is performed by setting the value in the D-A

conversion register. The result of D-A conversion is output from

the DA pin by setting the DA output enable bit to “1”.

When using the D-A converter, the PB0/DA port direction register

bit must be set to “0” (input status).

The output analog voltage V is determined by the value n (deci-

mal notation) in the D-A conversion register as follows:

V = VREF ✕ n/256 (n = 0 to 255)

Where VREF is the reference voltage.

At reset, the D-A conversion register is cleared to “0016”, and the

DA output enable bit is cleared to “0”, and PB0/DA pin becomes

high impedance.

The DA output does not have buffers. Accordingly, connect an ex-

ternal buffer when driving a low-impedance load.

Set VCC to 3.0 V or more when using the D-A converter.

Fig. 62 Block diagram of D-A converter

Fig. 63 Equivalent connection circuit of D-A converter

PB0/DA

D-A conversion register (8)

R-2R resistor ladder

DA output enable bit

AVSS

VREF

“0”

“1”

MSB

“0”

“1”

LSB

PB0/DA

D-A conversion register

DA output enable bit

M38B74FD Datasheet(PDF) 62 Page - Renesas Technology Corp