SM8146AD1 データシートの表示（PDF） - Nippon Precision Circuits
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SM8146AD1 Datasheet PDF : 19 Pages
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SM8146AD1
OPERATIONAL DESCRIPTION
EL Sheet
I EL Emission Condition
An AC (30Hz to several kHz) high voltage (60Vp-p to several hundred Vp-p) is required for EL emission. The
SM8146AD1 supports an EL drive frequency range of 31Hz to 1500Hz and an EL drive voltage range of
86Vp-p to 170Vp-p.
I EL Life
The EL drive frequency and EL drive voltage have a simultaneous affect on the EL brightness and EL life span.
The EL life decreases when the EL brightness is high, so an optimized value should be selected for the EL
sheet used. The EL life also has an effect on the EL drive voltage waveform. The SM8146AD1 EL drive volt-
age waveform is a sine wave with small high-harmonic components which helps to extend EL life.
I EL Audible Noise
The EL sheet has a piezoelectric characteristic that generates audible noise when excited by the applied AC
high voltage. The SM8146AD1 EL drive voltage waveform is a sine wave with small high-harmonic compo-
nents which helps to reduce EL audible noise. The EL drive waveform sine wave, generated by the EL drive
circuit, does not require an output resistor. Consequently, peripheral components and a corresponding drop in
power efficiency can be avoided.
I EL Drive Voltage (Constant-Voltage Control and Overvoltage Protection)
The SM8146AD1 uses constant-voltage control where the EL drive voltage is set to 7 stabilized voltage ampli-
tude levels determined by the IC internal circuitry. The EL drive voltage amplitude is initially set to the default
value of 85V, and then changes in sync with the falling edge of each DIM input pulse in the continuous
sequence 85V → 78V → 71V → 64V → 57V → 50V → 43V → 0V (OFF) → 85V. The EL drive voltage con-
stant-voltage control not only eliminates EL brightness variations due to supply voltage fluctuations, but also
functions as overvoltage protection when the EL load is removed.
Interface
The SM8146AD1 uses an interface comprised by the ENA and DIM input pins. The ENA and DIM pins have a
HIGH-level input voltage range of 1.4V to VDD + 0.3V, enabling direct control from a 1.8V system microcon-
troller without the need for a voltage converter. Pull-down resistances are built-in.
I ENA Pin
The ENA pin functions as the IC ON/OFF control. The device is enabled when ENA is HIGH, and disabled
when ENA is LOW.
I DIM Pin
The DIM pin functions as the EL brightness adjustment (dimming) control. The EL drive voltage amplitude
reduces in sync with the falling edge of each DIM input pulse in the continuous sequence 85V → 78V → 71V
→ 64V → 57V → 50V → 43V → 0V (OFF) → 85V. The DIM pin should be connected to GND when EL
brightness control is not used.
SEIKO NPC CORPORATION —5
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