Datasheet BridgeSwitch Family (Power Integrations) - 5

BridgeSwitch BridgeSwitch Functional Description
R and R in Figure 6). External supply voltage V is greater than SL SH SUP bypass shunt regulator voltage V plus the voltage drop of BridgeSwitch combines two high-voltage power FREDFETs, gate BPX(SHUNT) bootstrap diode D . A typical value is V = 17 V. Resistors R and drivers and control ers into a single package. The FREDFETs are SH SUP SL R limit the external supply current to less than 12 mA (1.5 - 2 mA connected in a half-bridge configuration where their diode structure SH recommended). Shorting BPL pins or BPH pins from separate devices (ultra-soft and ultra-fast recovery) makes them ideal for hard- directly together is not recommended. switched inverter-based motor drivers.
BYPASS LOW-SIDE Pin and HIGH-SIDE Pin
To reduce external components, the drive control ers feature integrated
Undervoltage Threshold
high-voltage current sources, al owing them to draw current directly The BYPASS LOW-SIDE pin and BYPASS HIGH-SIDE pin undervoltage from the high-voltage DC Bus. The high-side control er provides circuitries disable the respective power FREDFET when either the high-side status updates to the low-side control er which generates BYPASS LOW-SIDE pin voltage or the BYPASS HIGH-SIDE pin voltage an instantaneous phase-current output signal (BRD126X). This drops below V -V or V -V , respectively, in steady-state BPL BPL(HYST) BPH BPH(HYST) unique capability al ows the implementation of a sensor-less operation. Once either the BYPASS LOW-SIDE pin voltage or the motor-control scheme. The control ers also ensure that the FREDFET BYPASS HIGH-SIDE pin voltage fal below this threshold, it must rise turn-off is faster than turn-on resulting in an optimal balance back up to V or V , respectively to enable power FREDFET switching. BPL BPH between thermal performance and EMI.
BYPASS LOW-SIDE Pin and HIGH-SIDE Pins
BridgeSwitch offers integrated fault protection and system level
Capacitor Selection
monitoring via a bi-directional bussed single-wire status interface. Capacitors connected to the BYPASS LOW-SIDE pin and BYPASS Internal fault protection includes cycle-by-cycle current limit for both HIGH-SIDE pin supply bias current for the low-side and the high-side FREDFETs as well as two-level thermal overload protection. control er and deliver the required Gate charge for turning on the BridgeSwitch offers sophisticated DC-bus sensing, providing four low-side or the high-side power FREDFET. The BYPASS HIGH-SIDE pin undervoltage levels and one overvoltage level, and can also support capacitor supplies the high-side control er bias current over a time external sensors such as an NTC. Figure 3 shows the functional block interval which is a function of the high-side commutation duty ratio and diagram of the device along with key features. PWM frequency. The recommended maximum voltage ripple at the
BYPASS LOW-SIDE Pin and HIGH-SIDE Pin Regulator
BYPASS HIGH-SIDE pin capacitor over this time interval is 250 mV. The minimum required capacitance value for both bypass low-side and The BYPASS LOW-SIDE pin and the BYPASS HIGH-SIDE pin have bypass high-side is 0.33 internal regulators that charge the BYPASS LOW-SIDE pin capacitor mF. The recommended bypass low-side capacitance is 1 and the BYPASS HIGH-SIDE pin capacitor to V and V , respec- mF. BPL BPH tively. A current source connected to HIGH-SIDE DRAIN charges the Given application operating conditions determine the required bypass BYPASS LOW-SIDE capacitor. Another current source connected to high-side capacitance to keep ripple voltage below 250 mV. Figure 7 HIGH-SIDE DRAIN charges the BYPASS HIGH-SIDE capacitor depicts the minimum recommended BYPASS HIGH-SIDE pin capaci- whenever the low-side power FREDFET turns on. Both current sources tance as function of high-side commutation duty ratio D and PWM HS start charging once the HD pin voltage reaches V (min. 50 V). frequency. HD(START) The BYPASS LOW-SIDE and the BYPASS HIGH-SIDE pins are the internal supply voltage nodes for the low-side and the high-side 100 control ers and Gate drivers. When the low-side or the high-side f(PWM) 100 power FREDFETs are on, the device operates from the energy stored 500 in the BYPASS LOW-SIDE pin capacitor or the BYPASS HIGH-SIDE pin 1000 6000 capacitor, respectively.
PI-8309-080918
10000 10 16000 In addition, there are shunt regulators clamping the BYPASS LOW-SIDE 20000 pin to V and the BYPASS HIGH-SIDE pin to V when BPL(SHUNT) BPH(SHUNT) current is provided to the BYPASS LOW-SIDE pin and the BYPASS HIGH-SIDE pin from an external DC source through resistors (see 1
apacitance (
µ
F) Minimum recommended value in C HV Bus P H P HD B
0.1
BPH
CBPH RSH
HB
DSH
BPL
0.010.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 RSL CBPL
SG LS Maximum High-Side Commutation Duty Ratio DHS(MAX)
VSUP
+ -
Figure 7. BYPASS HIGH-SIDE Pin Capacitance vs. High-Side Commutation Duty Ratio and PWM Frequency. PI-8313-110518 Note that multilayer chip capacitors (MLCC) can exhibit a significant DC bias characteristic. Selecting a BYPASS HIGH-SIDE pin capacitor Figure 6. External BPL Pin and BPH Pin Power Supply Example. (according to Figure 7) needs to take the possible capacitance reduction into account when biasing at V . Refer to the respective BPH capacitor data sheet for details.
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Rev. I 01/20 www.power.com Document Outline Product Highlights Description Output Power Table Pin Functional Description BridgeSwitch Functional Description Application Example PCB Design Guidelines Absolute Maximum Ratings Thermal Resistance Key Electrical Characteristics Typical Performance Characteristics inSOP-24C Package Drawing Package Marking Part Ordering and MSL Table ESD and Latch-Up Table Part Ordering Information