In modern industrial automation systems, isolated drives are widely used in various high-voltage scenarios in industrial drive motors, inverters and switching power supplies and other circuit nodes to drive power semiconductor devices such as MOSFETs, IGBTs, and SiC MOSFETs and thus improve the operational accuracy, efficiency and reliability of industrial automation equipment.
Isolated drives, the "catalyst" for industrial automation processes
Isolated drivers are isolation devices that introduce isolation functionality into the gate driver and are responsible for acting as an interface between low voltage control signals and high power semiconductor switches while achieving electrical isolation. Its primary function is to provide the necessary voltage and current levels to effectively drive the power semiconductor devices and to enhance the system's immunity to interference.
Dual Channel Isolated Driver - Typical Functional Block Diagram (Example: CMT8602X)
At this stage, the optocoupler isolation drive is more widely used due to its advantages of simple use, low cost, small size, and no contact. However, there are common mode interference suppression capability is poor, isolation performance and reliability is not high enough, transmission delay is long and other issues, it is difficult to meet the requirements of the development of industrial isolation drive technology.
The capacitively coupled digital isolation drive external circuit can do opto-coupler isolation drive perfect compatibility, and in the anti common-mode interference suppression capability, isolation performance and reliability, transmission delay and drive capability and other indicators than opto-coupler isolation has a greater advantage, and better protection of low-voltage control circuits from high-voltage power circuits, to ensure the safety of the operator.
Product Recommendation, CMT8602X Isolated Gate Driver
Take the CMT8602X series of isolators independently developed by the veteran RF chip original manufacturer HOPERF as an example, the CMT8602X is an enhanced isolated dual-channel gate driver with 4A peak pull current and 6A peak sink current.
The CMT8602X input side is isolated from the two output drivers by a 5700 Vrms enhanced isolation layer with a minimum common mode transient immunity (CMTI) of 150 kV/us. The two secondary side drivers are internally functionally isolated from each other to support operating voltages up to 1500 VDC.
At the same time, the CMT8602X, as a special "RF chip" that adopts On-Off Keying (OOK) modulation technology to transmit data information, also has first-class propagation delay and pulse-width distortion. The maximum value of pulse width distortion (tPWD) of CMT8602X is only 9ns; the maximum value of transmission delay matching (tDM) between two channels (A/B) of CMT8602X is only 5ns.
CMT8602X Delay Matching and Pulse Width Distortion Measurement
Test conditions: VVCCI=3.3V or 5.0V, 0.1μF bypass capacitor between VCCI and GND, VVDDA=VVDDB=15V, 0.1μF bypass capacitor between VDDA and VDDB, GNDA and GNDB, TA=-40°C to +125°C.
The CMT8602X effectively removes the ground loop between two circuits through advanced isolation technology and optimised circuit design, blocking the propagation of common mode, surge and other interference signals.
CMT8602X Common Mode Transient Inhibition (CMTI) Test Circuit
CMT8602X Product Features
● General purpose: Dual low-side, dual high-side or half-bridge drivers
● Operating temperature range: - 40°C ~ 125°C
● 4A peak pull current, 6A peak sink current output
● 3V ~ 5.5V Input VCCI Operating Range, Connectable to Digital and Analogue Controllers
● Common mode transient immunity CMTI greater than 150 kV/us
● Barrier life > 40 years
● TLL and CMOS compatible
● Up to 30V VDD output drive supply, 9V and 13V VDD UVLO options
● Switching parameters:
40 ns typical propagation delay
50 ns minimum pulse width
5 ns max delay match
9 ns maximum pulse width distortion
● Programmable overlap and dead time
● Suppression of input pulse and noise transients shorter than 25ns
● Power sequencing quick disable
● Safety-related certifications:
8000 VPK Enhanced Isolation according to DIN V VDE V 0884-11:2017-01
UL1577 compliant and up to 1 minute 5700 VRMS isolation
It has obtained the CSA certification and complies with the terminal equipment standards of IEC 60950-1, IEC 62368-1, IEC 61010-1, and IEC 60601-1.
Apply for CQC certification, compliant with GB4943.1-2011 standard
● Available in SOW14 / SOW16 / SOP16 packages
CMT8602X Product Applications
● HEV and EV Battery Chargers
● Isolated Converters in DC/DC and AC/DC Power Supplies
● Motor drives and DC/AC PV inverters
● LED lighting
● induction heating
● Uninterruptible power supply (UPS)
The CMT8602X is a flexible dual gate driver that can be configured to fit a variety of power and motor drive topologies, as well as to drive many types of transistors.
