STK433-090-E

No. A1248-10/11

2) Load short-circuit detection block

Since the voltage between point B and point C is less than 0.6V in normal operation mode (VBE < 0.6V) and TR1 (or

TR2) is not activated, the load short-circuit detection block does not operate.

When a load short-circuit occurs, however, the voltage between point B and point C becomes larger than 0.6V,

causing TR1 (or TR2) to turn on (VBE > 0.6V), and current I2 to flows.

3) Latch-up circuit block

TR3 is activated when I2 is supplied to the latch-up circuit.

When TR3 turns on and current I3 starts flowing, VST goes down to 0V (standby mode), protecting the power

amplifier.

Since TR3 and TR4 configure a thyristor, once TR3 is activated, the IC is held in the standby mode.

To release the standby mode and reactivate the power amplifier, it is necessary to set the standby control voltage (*2)

temporarily low (0V). Subsequently, when the standby control is returned to high, the power amplifier will become

active again.

(*4) The I3 value varies depending on the supply voltage. Determine the value of R2 using the formula below, so that

I1 is equal to or less than I3.

I1

≤ I3 = VCC/R2

4) DC offset protection block

The DC offset protection circuit is activated when

±0.5V (typ) voltage is applied to either "OUT CH1" or "OUT

CH2," and the hybrid IC is shut down (standby mode).

To release the IC from the standby mode and reactivate the power amplifier, it is necessary to set the standby control

voltage temporarily low (0V).

Subsequently, when the standby control is returned to high (+5V, for example), the power amplifier will become

active again.

The protection level must be set using the 82k

Ω resistor. Furthermore, the time constant must be determined using

22

μ//22μ capacitors to prevent the amplifier from malfunctioning due to the audio signal.

STK433-100 Series BTL Application

2

3

4

5

67

8

9

10

11

12

13

14

1

15

+VCC

-VCC

STK433-100-E series

OUT

10

μF

/10V

4.7

Ω

0.1

μF

56k

Ω

3pF

56k

Ω

3pF

GND

Ch1 IN

2.2

μF

/50V

1k

Ω

+VCC

Ch1

IN

Ch1

NF

Ch2

IN

Ch2

NF

Ch2

OUT

Ch1

OUT

-VCC

SUB

GND

+PRE

ST-BY

100

μF

/100V

1.8k

Ω

100

μF

/100V

1.8k

Ω

Stand-by Control

Ch1

OUT

Ch2

OUT

-PRE

100

Ω

/1W

3

μH

100pF

0.22

Ω

0.22

Ω

4.7

Ω

3

μH

4.7

Ω/1W

0.1

μF

4.7

Ω

/1W

RL=8Ω

56k

Ω

33

μF

33

μF

10

μF

/10V

100

Ω/1W

100

μF

/100V

(*1) R1

(*1) The voltage applied to the Stand-by pin (#13) must not

exceed the maximum rated value (VST max).