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Número de pieza

componentes Descripción

Fabricante

3544L_OLD

HEADPHONE AMPLIFIER FOR CD-ROMS

Unisonic Technologies 

UTC 3544 LINEAR INTEGRATED CIRCUIT

APPLICATION EXAMPLE

330μ

Vcc

+

+

1μ

+ 47μ

Vcc

8

OUT2

7

BIA

S

6

IN2

5

VIN2

TSD

BIAS

6dB

+

+

6dB

90K

90K

VMUTE

H:Active

L:Mute

MUTE

1

OUT1

+

2

MUTE

3

IN1

100k

1μ

4

GND

1μ

VIN1

EXPLANATION OF EXTERNAL XOMPONENTS

(1)Input coupling capacitor(C3 and C5)

Determined by the low-band cut-off frequency.Since the input impedance for this IC is 180kΩ,it can be

determined by the formula below,but take into consideration the fluctuations,ambent temperature,etc.(a

multi-layered ceramic capacitor is recommended).

C3(C5)=1/(2π×180kΩ×f)

(2)BIAS capacitor(C6)

47μF when Vcc=5V,and 33μF when Vcc=3V.If the capacitance is lowered too much,the electrical

characteristics will be adversely affected and popping noise may occur.Therefore,take th sufficient considerations

before changing these values.

(3)MUTE pin for anti-pop measures(R2 and C2)

Possesses an impedance of 190kΩ with respect to GND,so if R2 is increased too much,the MUTE mode may

become unable to be released.

(4)Output coupling capacitor(C1 and C7)

Determined by the low-band cutoff frequency.As the output load resistance value RL(assuming that for output

protection or current limiting,a resistor Rx will be inserted),it can be determined by the formula below.

C1(C7)=1/(2π×(RL+Rx) ×f)

(5)Input gain adjustment resistor(R3 and R4)

Input gain adjustment can by performed by extemal resistors R3 and R4,The desired gain can be set by the

formula givev below.

Gvc=6+20log(90kΩ/(90kΩ+R3))［ dB ］

UTC UNISONIC TECHNOLOGIES CO. LTD 6

QW-R107-040,A

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