TB2905HQ Toshiba, TB2905HQ Datasheet - Page 3

• 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

Operational Description
1. Voltage Gain
2. Standby Switching Function
< Advantages of standby switching >
Pin 4 control voltage: V
within the IC.
eliminates the need for an NF capacitor, resulting in lower total application cost and smaller mounting
space.
down by controlling the state of pin 4
(standby pin).
approximately 3 VBE (typ.). The supply
current in standby state is approximately 2
µA (typ.).
When changing the time constant for pin 4, check the pop noise produced.
(1)
(2)
The TB2905HQ has no NF (negative feedback) pins. Therefore, the voltage gain (G
Therefore, the total voltage gain is determined by the following expression:
Although this configuration without an NF pin does not allow the user to adjust voltage gain, it
The TB2905HQ can be powered up or
The threshold voltage for pin 4 is
Stand-by
OFF
ON
Voltage gain of amplifier 1: G
Voltage gain of amplifiers 2A and 2B: G
Voltage gain obtained by BTL connection: G
G
The microcontroller can directly turn V
Since the control current is microscopic, a switching relay with small current capacity is satisfactory
for switching.
V
= G
V1
+ G
Power
OFF
ON
V2
+ G
(Each description applies to a single channel)
V (BTL)
Figure 1 Amplifier Configuration
Input
V
2.5~6 V
0~0.5
SB
SB
= 0 + 20 + 6 = 26dB
(V)
V1
(Pin 4)
= 0 dB
Amplifier 1
CC
V2
= 20 dB
on or off without using a switching relay.
3
V (BTL)
Figure 2 Driving pin 4 high powers up
Amplifier 2A
OFF
ON
Amplifier 2B
= 6 dB
Power
4
the TB2905HQ
10 kΩ
V
CC
≈ 2 V
V
) is determined
BE
To bias
cutoff circuit
TB2905HQ
2005-08-17