stk433-290-e Sanyo Semiconductor Corporation, stk433-290-e Datasheet - Page 12

• Manufacturer Part Number: stk433-290-e
• Description: Thick-film Hybrid 3-channel Class Audio Power 3-channel Class Audio Power
• Manufacturer: Sanyo Semiconductor Corporation

2) Load short detection block
1) Stand-by control circuit block
-PRE
Concerning pin 13 reference voltage VST
3) Latch-up circuit block
4) DC offset protection block
1
Since the voltage between point B and point C is less than 0.6V in normal operation mode (V BE < 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 (V BE > 0.6V), and current I2 to flows
When I2 was supplied to latch-up circuit, TR3 operate.
VST becomes Stand-By Mode (0V) when TR3 operates (I3 flows), the power amplifier is protected.
Stand-By Mode is maintained when once TR3 operates because TR3 and TR4 compose the thyristor.
It is necessary to make the Stand-By Control voltage (*2) L (0V) once to release Stand-By mode and to make the
power amplifier operate again.
After, when Stand-By Control (*2) is returned to H (ex, +5V), it operates again.
(*4) I3 is changed depending on the power-supply voltage (-V CC ).
The DC offset protection circuit is activated when ±0.5V (typ) voltage is applied to either "OUT CH1" or "OUT
CH2," or "OUT CH3," 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 82kΩ resistor. Furthermore, the time constant must be determined using
22μ//22μ capacitors to prevent the amplifier from malfunctioning due to the audio signal.
(Reference example) STK433-300-E series test circuit (when +5V is applied to Stand-by control.)
STK433-300-E series
<1> Operation Mode
<2> Stand-By Mode
(*1) The current limiting resistor (R1) must be used to ensure that the voltage flowing into the stand-by pin (pin 13)
(*2) The pop noise level when the power is turned on can be reduced by setting the time constant with a capacitor in
(*3) Determines the time constant at which the capacitor (*2) is discharged in standby mode.
-V CC
2
Please set resistance (R2) to become I1 < I3 by the following calculation types.
When the voltage flowing into pin 13 (VST) is stopped (=0V), the switching transistor in the bias circuit turns
off, placing the amplifier into the standby mode.
does not exceed its maximum rated value VST max.
operating mode.
The switching transistor in the bias circuit turns on and places the amplifier into the operating mode when the
voltage flowing into pin 13 (VST) becomes 0.25V or greater.
+V CC
3
OUT
Ch1
4
I1 ≤ I3 = V CC /R2
OUT
Ch1
5
OUT
Ch2
6
OUT
Ch2
7
+PRE
8
SUB
9
GND
10
Stand-By Circuit
in PreDriver IC
Ch1
11
IN
ΔVBE
Ch1
4.7kΩ
12
NF
STK433-290-E
ST-BY
13
14
Ch2
NF
Ch2
15
IN
Ch3
16
IN
VST
Ch3
17
NF
OUT
Ch3
18
(*1) R1
2.7kΩ
OUT
Ch3
19
ΔVBE
ex) Stand-By control voltage=+5V
VST=(5V-VBE×2)×4.7kΩ/((*1)+4.7kΩ)+VBE
=(5V-0.6V×2)×4.7kΩ/(4.7kΩ+2.7kΩ)+0.6V
≈3.0(V)
33μF
(*2)
1kΩ (*3)
33kΩ
2kΩ
(*3)
Stand-by Control Voltage
H: Operation Mode (+5V)
L: Stand-by Mode (0V)
No. A1630-12/13