TB2905HQ Toshiba, TB2905HQ Datasheet - Page 4

• Manufacturer Part Number: TB2905HQ
• Manufacturer: Toshiba

Specifications of TB2905HQ

• No. Of Channels: 4
• Package: HZIP 25-P-1.00F
• Recommended Vcc (v): 13.2
• Rl=2 Ohm: 80W x 4
• Rl=4 Ohm: 50W x 4
• Rl=8 Ohm: -
• Features/built-in Functions: 4 BTL channels, standby switch, mute, BiCD process, Class-KB high efficiency
• Operating Voltage (v): 9 to 18

3. Muting Function
The time constant for muting is determined from R1 and C4. Select the constants considering the pop noise
that is produced when powering the TB2905HQ on/off or turning muting on/off. (See Figures 4 and 5.)
Pin 22 is designed to be controlled at 3.3 V.
The pin functions as a current source switch for the internal muting circuit and is designed so that its
discharging current is 200 µA. The value of the external pull-up resistor is based on this current.
cannot take in the current if the pull-up resistance is too low. The series resistance (R1) for pin 22 must,
therefore, be at least 47 kΩ.
Figure 4 Muting function
3.3Ｖ
Driving pin 22 low triggers audio muting.
Example: When changing the control voltage from 3.3 V to 5 V, 5 V/3.3 V x 47 kΩ = 71 kΩ
The TB2905HQ internally triggers muting when the voltage is dropped, taking in a current of 200 µA. It
R
1
C
4
22
1 kΩ
Stand-By
(Pin 22)
V
CC
Large-current capacity switch
Small-current capacity switch
Muting
ON/OFF control
Figure 3 Standby switching
V
CC
Battery
Battery
- Conventional method -
- Standby switching -
4
Figure 5 Muting attenuation − VMUTE (V)
−100
−120
From microcontroller
−20
−40
−60
−80
20
0
0
Vcc = 13.2 V
f = 1kHz
R
V
V
L
OUT
Stand-By
CC
= 4 Ω
= 20dBm
0.5
Muting pin voltage: V
V
1
Relay
CC
ATT – V
1.5
MUTE
From microcontroller
MUTE
Battery
Battery
2
(V)
2.5
TB2905HQ
2005-08-17
3