3886 datasheet(82/380 Pages) RENESAS

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3886 Group User’s Manual

HARDWARE

D-A CONVERTER

The 3886 group has two internal D-A converters (DA1 and DA2)

with 8-bit resolution.

The D-A converter is performed by setting the value in each D-A

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

the DA1 or DA2 pin by setting the DA output enable bit to “1”.

When using the D-A converter, the corresponding port direction

“0” (input status).

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

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 registers are cleared to “0016”, the

DA output enable bits are cleared to “0”, and the P56/DA1/PWM01

and P57/DA2/PWM11 pins become high impedance.

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

ternal buffer when driving a low-impedance load.

Set VCC to 4.0 V or more when using the D-A converter.

Fig. 52 Block diagram of D-A converter

Fig. 53 Equivalent connection circuit of D-A converter (DA1)

FUNCTIONAL DESCRIPTION

P56/DA1/PWM01

D-A1 conversion register (8)

R-2R resistor ladder

DA1 output enable bit

P57/DA2/PWM11

D-A2 conversion register (8)

R-2R resistor ladder

DA2 output enable bit

AVSS

VREF

“0”

“1”

MSB

“0”

“1”

LSB

P56/DA1/PWM01

D-A1 conversion register

DA1 output enable bit

3886 Datasheet(PDF) 82 Page - Renesas Technology Corp

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