Datasheet TPD4162F (Toshiba) - 7

TPD4162F
(3) Under-voltage protection The IC incorporates under-voltage protection circuits to prevent the IGBT from operating in unsaturated mode when the VCC voltage or the VBS voltage drops. When the VCC power supply falls to the IC internal setting VCCUVD = 11 V (typ.), all IGBT outputs are shut down regardless of the input. This protection function has hysteresis. When the VCC power supply reaches 0.5 V higher than the shutdown voltage VCCUVR = 11.5 V (typ.), the IC is automatically restored and the IGBT is turned on/off again by the input. When the VBS supply voltage drops VBSUVD = 3.0 V (typ.), the high-side IGBT output shuts down. When he VBS supply voltage reaches 0.5 V higher than the shutdown voltage VBSUVR = 3.5 V (typ.) VBS supply voltage reaches 0.5 V higher than the shutdown voltage VBSUVR = 3.5 V (typ.), the IGBT is turned on/off again by the input signal. (4) Thermal shutdown The IC incorporates a thermal shutdown circuit to protect itself against excessive rise in temperature. When the temperature of this chip rises to the internal setting TSD due to external causes or internal heat generation, all IGBT outputs are shut down regardless of the input. This protection function has hysteresis ∆TSD = 50 °C (typ.). When the chip temperature falls to TSD − ∆TSD, the chip is automatically restored and the IGBT is turned on/off again by the input. Because the chip contains just one temperature-detection location, when the chip heats up due to the IGBT for example, the distance between the detection location and the IGBT (the source of the heat) can cause differences in the time taken for shutdown to occur. Therefore, the temperature of the chip may rise higher than the thermal shutdown temperature.
7.4. Description of Bootstrap Capacitor Charging and Its Capacitance
The IC uses bootstrapping for the power supply for high-side drivers. The bootstrap capacitor is charged by turning on the low-side IGBT of the same arm (approximately 1/5 of PWM cycle) while the high-side IGBT controlled by PWM is off. For example, to drive at 20 kHz, it takes approximately 10 μs per cycle to charge the capacitor. When the VS voltage exceeds 3.8 V (55 % duty), the low-side IGBT is continuously in the off state. This is because when the PWM on-duty becomes larger, the arm is short-circuited while the low-side IGBT is on. Even in this state, because PWM control is being performed on the high-side IGBT, the regenerative current of the diode flows to the low-side FRD of the same arm, and the bootstrap capacitor is charged. Note that when the on-duty is 100 %, diode regenerative current does not flow; thus, the bootstrap capacitor is not charged. When driving a motor at 100 % duty cycle, take the voltage drop at 100 % duty (see the figure below) into consideration to determine the capacitance of the bootstrap capacitor. Capacitance of the bootstrap capacitor = Current dissipation (max) of the high-side driver × Maximum drive time /(VCC − VF (BSD) + VF (FRD) − 13.5) [F] VF (BSD) : Bootstrap diode forward voltage VF (FRD) : Fast recovery diode forward voltage Consideration must be made for aging and temperature change of the capacitor. Duty cycle 100 % (VS: 5.4 V) Duty cycle 80 % C Triangular wave Duty cycle 55 % (VS: 3.8 V) PWM reference voltage B Duty cycle 0 % (V S: 2.1 V) VVsOFF (V S: 1.3 V) Low-side ON High-side duty ON A GND
VS Range IGBT Operation
A Both high and low-side OFF. B Charging range. Low-side IGBT refreshing on the phase the high-side IGBT in PWM. C No charging range. High-side at PWM according to the timing chart. Low-side no refreshing. © 2 020 7 2020-02-20 Toshiba Electronic Devices & Storage Corporation