SM1350XXXM 查看數據表（PDF） - Nippon Precision Circuits

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SM1350XXXM

High Tone Quality Melody LSI

Nippon Precision Circuits  

SM1350 series

Melody Output Circuit

The volume control circuit comprises a P-channel

current-summing D/A converter, a built-in constant-

current source and an external variable resistor. The

circuit is set for either BTL output or A-class output

by master-slice option.

BTLoutput

The BTL output comprises a pair of 9-bit D/A

converters and 4 external transistors (2 × NPN + 2 ×

PNP) to drive a speaker.

VDD

MSB

MSBN

SP

SPN

VSS VOL

VDD

C

SPEAKER

VSS

Figure 4. BTL output circuit

A-class output circuit

The A-class output circuit comprises a single 10-bit

D/A converter with current output on SP. The D/A

converter MSB is set ON immediately after the

oscillator starts, and the current output that results is

the center point above and below which the converter

current output varies in response to the waveform

amplitude. The SP output is current-to-voltage

converted for connection to audio equipment or

amplifiers. In A-class output mode, the 4 sound

generator waveforms are time multiplexed, so an

integrating circuit must be connected between SP

and the amplifier to recover the signal.

VDD

BUSYN

VSS VOL

SP

VDD

AMP

SPEAKER

VSS

Note: Refer to the "TIMING DIAGRAMS" section to confirm melody timing specifics.

Figure 5. A-class output circuit

NIPPON PRECISION CIRCUITS—9

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