TB2939HQ 查看數據表（PDF） - Toshiba

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产品描述 (功能)

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TB2939HQ

45W ×4-ch BTL Audio Power IC

Toshiba 

TB2939HQ

2. Mute Function (pin 22)

The audio mute function is enabled by setting pin 22 Low. R1 and C4 determine the time constant of the

mute function. The time constant affects pop noise generated when power or the mute function is turned on

or off; thus, it must be determined on a per-application basis. (Refer to Figures 4 and 5.)

The value of the external pull-up resistor is determined, based on pop noise value.

For example, when the control voltage is changed from 5 V to 3.3 V, the pull-up resistor should be:

3.3 V/5 V × 47 kΩ = 31 kΩ

5V

22

R1

C4

1 kΩ

Mute On/Off

control

Figure 3 Mute Function

ATT – VMUTE

20

VCC = 13.2 V

0 f = 1 kHz

RL = 4 Ω

VO = 20dBm

−20 BW = 400 Hz to 30 kHz

−40

−60

−80

−100

−120

0

0.5

1

1.5

2

2.5

3

Pin 22 control voltage: VMUTE (V)

Figure 4 Mute Attenuation − VMUTE (V)

3. Diagnosis Output (pin 25)

This diagnosis output terminal of pin 25 has open collector output structure on chip as shown in Figure 5.

In case diagnosis circuit that detect unusual case is operated, NPN transistor (Q1) is turned on.

It is possible to protect all the system of apparatus as well as power IC protection.

In case of being unused this function, use this IC as open-connection on pin 25.

5V

OUTPUT OFFSET

VOLTAGE

DETECTOR

OUTPUT SHORT

PROTECTOR

OVER VOLTAGE

PROTECTOR

25

Q1

5V

GND

t

Q1 is turned on

Figure 5 Self Diagnosis Output

4

Rev-1.0 2009-01-21

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