CXA2513M View Datasheet(PDF) - Sony Semiconductor

Part Name

Description

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CXA2513M

3-Band Preset Graphic Equalizer IC (with standby and memory on last preset mode)

Sony Semiconductor 

CXA2513M

3. Mute Pulse Generation

The CXA2513M has one voltage comparator built-in. The built-in voltage comparator is used to produce mute

pulse during the depress of the preset mode switches. During depress the switch, there is a voltage pulse of

about 1V depending appearing at the cathode of the LEDs.

The mute detector comparator is used to detect this voltage changes at the cathode of LEDs and produce

mute pulse at Pin 12. The polarity of the mute pulse can be set. When the M_DET+ pin (Pin 18) is higher than

the M_DET– pin (Pin 17), the MUTE pin (Pin 12) will be high. When the M_DET+ pin (Pin 18) is lower than the

M_DET– pin (Pin 17), the MUTE pin (Pin 12) becomes low.

A capacitor is used to store the initial voltage before the depression of the mode switch. Once the switch is

depressed, the capacitor starts discharge. The values of the resistors and capacitor set the duration of the

mute pulse.

Notes on Operation

1) Value of Timing Capacitor

The timing and the duration of the MUTE pin and the LEDs light-up depends on the value of the timing

capacitor as the timing capacitor is discharging to (VCC – 5∗VBE).

The charging time constant is 250K∗(timing capacitor) and the discharging time constant is 150K∗(timing capacitor).

The two threshold values:

a) Latch Output Enable (LATCH_OE_ctl)

b) Latch enable/Mute disable (LATCH_ctl)

The threshold values of the Latch Output Enable (LATCH_OE_ctl) is set to (VCC – 3∗VBE) and the threshold

values of the Latch enable/Mute disable (LATCH_ctl) is set to (VCC – 4∗VBE).

So, the duration for all the LEDs light-up is

2∗VBE = (5VBE) exp (–t1/RC)

where R = 150K

and the sound appears after t2 seconds if the mute pulse output pin is used. This t2 is given by

VBE = (5VBE) exp (–t2/RC)

where R = 150K

Therefore, depending on the requirements of the time on the mute sound and the duration of all LEDs light-up,

choose the value of the timing capacitors.

– 16 –

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