STK433-070-E
STK433-000 Series Application Explanation
Stand-by Circuit
in Pre Driver IC
SW transistor
4.7kΩ (*3)
STK433-000 series
ΔV
BE
1) Stand-by control circuit part
H: Operation mode (+5V)
L: Stand-by mode (0V)
Ch1
Ch1
Ch2
Ch2
Ch1 Ch1
Ch2
Ch2
IN
-PRE -V
1
+V
+PRE
8
GND
ST-BY
NF
SUB
9
IN
NF
CC
OUT(+)
OUT(-) OUT(+)
OUT(-)
CC
2
3
4
6
7
10
11
12
13
14
15
1kΩ
5
6.8kΩ
6.8kΩ
56kΩ
33kΩ
56kΩ
(*1) R1
Stand-By control
Voltage VST
Tr5
I1
ex)5.1kΩ
2kΩ
33μF
Tr1
Tr2
Point.B
Point.B
Point.C
I2
Point.C
22kΩ
56kΩ
Operate mode (VST
) ≥ 2.5V
) < 0.6V (0V typ)
OFF
Stand-By mode (VST
ON
(2) Load short
detection part
I3
Tr4
(*4) R2
1kΩ
0.1μF
10kΩ
Tr3
(3) Latch-up
circuit part
100kΩ
-V
CC
Tr5
82kΩ
Tr6
OUT Ch1
OUT Ch2
22μF
82kΩ 22μF
100
kΩ
(4) DC offset
protection
The protection circuit application for the STK433-000sr consists of the following blocks (blocks (1) to (4)).
(1) Standby control circuit block
(2) Load short-circuit detection block
(3) Latch-up circuit block
(4) DC voltage protection block
1) Standby control circuit block
Concerning pin 13 reference voltage VST
<1> Operation mode
The switching transistor of the predriver IC turns on when the pin 13 reference voltage, VST, becomes greater
than or equal to 2.5V, placing the amplifier into the operation mode.
Example: When VST (min.) = 2.5V
I1 is approximately equal to 0.40mA since VST = (*2) × IST + 0.6V → 2.5V = 4.7kΩ × IST + 0.6V.
<2> Standby mode
The switching transistor of the predriver IC turns off when the pin 13 reference voltage, VST, becomes lower
than or equal to 0.6V (typ. 0V), placing the amplifier into the standby mode.
Example: When VST = 0.6V
I1 is approximately equal to 0mA since VST = (*2) × IST + 0.6V → 0.6V = 4.7kΩ × IST + 0.6V.
(*1) Limiting resistor
Determine the value of R1 so that the voltage VST applied to the standby pin (pin 13) falls within the rating
(+2.5V to 5.5V (typ. 3.0V)).
(*2) The standby control voltage must be supplied from the host including microcontrollers.
(*3) A 4.7kΩ limiting resistor is also incorporated inside the hybrid IC (at pin 13).
No. A1488-9/11
SANYO [ SANYO SEMICON DEVICE ]
