
TA8083P/F
2004-12-24
5
Description of Multi-detection Operation
The TA8083P and TA8083F has functions for detecting overvoltage (VSD), overcurrent (ISD), and overheating
(TSD). These functions temporarily protect the IC (and the motor load in some cases) from deterioration or
destruction due to power-related overstress.
The three functions work independently and each function is explained below.
Note 1: These functions are intended to protect the IC from instantaneous faults, including output short circuits, and
are not designed to protect the IC from all types of faults.
Note 2: If the IC is used beyond the maximum ratings, it may be damaged before the detection circuits are
activated.
Note 3: These functions are not activated if the operating voltage is less than 8 V. In this range, short-circuiting the
output can cause damage to the IC.
1. Overvoltage detection (VSD)
Basic operation
When the voltage supplied to the VCC pin is up to the VSD detection voltage, the output is controlled by the
input signals. However, when the VCC voltage exceeds the detection voltage, the output enters
high-impedance state regardless of the input signals.
Detailed explanation
The VSD voltage is detected by an internal zener diode. If the input voltage is higher than the zener voltage,
a signal to turn off the output transistors is sent to the control logic. If it is lower than the zener voltage,
the logic is controlled by the input signals from DIA and DIB.
2. Overheat detection (TSD)
Basic operation
When the junction (chip) temperature is up to the TSD detection temperature, the output is controlled by
the input signals. When it exceeds the TSD detection temperature, the output enters high-impedance state
regardless of the input signals.
Detailed explanation
The temperature is detected by monitoring the VF of a diode on the chip. When the diode VF is lower than
the internal reference voltage, a signal to turn off the output transistors is sent to the control logic. When it
is higher than the internal reference voltage, the logic is controlled by the input signals from DIA and DIB.
Control logic
M (
+)
M (
)
DIA
DIB
VSD
ISD
TSD