TA84006F/FG
Equivalent Circuit
<Overcurrent detector (RF, VISD, ISD) >
• Input to the VISD1 pin the voltage generated at the overcurrent detection resistor RF connected to the
RF pin.
• At chopping ON, voltage spikes at the RF pin as a result of the Pch-MOS output capacitance. To cancel
the spike, externally connect a capacitor to the VISD2 pin. (10 kΩ resistor built-in)
• If the VISD2 pin voltage exceeds the internal reference voltage (VRF = 0.5 V), the overcurrent detection
output ISD pin goes Low.
Inputting the inversion of the ISD pin output to the TB6537P/PG/F/FG or TB6548F/FG OC pin limits the
PWM ON time and the current at the ISD output rising edge.
VCC
VISD1 10 kΩ VISD2
ISD
External
capacitor
<Pin voltage detector (COMP) >
• The pin voltage detector outputs the result of OR-ing the output pin voltages and the virtual mid-point N
voltage to determine the majority.
(If at least two phases of the three-phase output are greater than the mid-point potential, the detector
outputs “Low”. Conversely, if at least two phases are smaller than the mid-point potential, the circuit
outputs “High”.)
VCC
Majority-determining
OR data
COMP
GND
• With the virtual mid-point potential VN used as the reference for the pin voltage detection circuit
considered as half the voltage applied to the motor, then
VN = [ (VM − Ron (upper) *IO) − (Vsat (lower) + VRF) ]/2 + Vsat + VRF
= [VM − VRF + Vsat (lower) − Ron (upper) *IO]/2 + VRF.
Here, assuming that: Vsat (lower) − Ron (upper) *IO ∼− VF,
we have set the following: VN = [VM − VRF + VF]/2 + VRF
<Overheating protector>
• Automatic restoration
• Temperature hysteresis supported
TSD (ON) = 165°C
TSD (HYS) = 30°C
TSD (OFF) = 135°C
9
2004-08-10