UCC21521DWR Isolators

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1. Describe

The UCC21521DWR is an isolated dual-channel gate driver with 4A source and 6A peak sink current. It is designed to drive power MOSFETs, IGBTs and SiC MOSFETs up to 5MHz with best-in-class propagation delay and pulse width distortion. The input side is isolated from the two output drivers by a 5.7kVRMS reinforced isolation barrier with a minimum common-mode transient immunity (CMTI) of 100V/ns. Internal functional isolation between the two secondary side drivers allows operating voltages up to 1500 VDC. Each driver can be configured as two low-side drivers, two high-side drivers, or a half-bridge driver with programmable dead time (DT). Pulling the EN pin low turns off both outputs simultaneously and allows normal operation when left open or pulled high. As a fail-safe measure, a primary-side logic fault forces both outputs low. The device accepts VDD supply voltages up to 25 V. The wide input VCCI range of 3 V to 18 V makes the driver suitable for interfacing with analog and digital controllers. All supply voltage pins have undervoltage lockout (UVLO) protection. With all these advanced features, UCC21521 can achieve high efficiency, high power density and robustness in various power supply applications.

2. Feature

    1. Universal: Dual low-side, dual high-side or half-bridge drivers

    2. Operating temperature range –40 to +125°C

    3. Switch parameters:

        – 19-ns typical propagation delay

        – 10ns minimum pulse width

        – 5ns maximum delay matching

        – 6ns maximum pulse width distortion

    4. Common Mode Transient Immunity (CMTI) greater than 100 V/ns

    5. Surge immunity up to 12.8 kV

    6. Barrier life > 40 years

    7. 4A peak source current, 6A peak sink current output

    8. TTL and CMOS compatible inputs

    9. 3-V to 18-V input VCCI range to interface with digital and analog controllers

  10. Up to 25V VDD output drive power

        – 5V, 8V, 12V VDD UVLO options

  11. Programmable overlap and dead time

  12. Rejects input pulses and noise transients less than 5 ns

  13. Quick enable power sequencing

  14. Wide body SOIC-16 (DW) package

3. Application

    1. Isolated converters in off-line AC to DC power

    2. Server, Telecom, IT and Industrial Infrastructure

    3. Motor drives and DC to AC solar inverters

    4. LED lighting

    5. Induction heating

    6. Uninterruptible Power Supply (UPS)

4. Pin configuration

5. Function description

The UCC21521DWR has internal undervoltage lockout (UVLO) protection on the power block between the VDD and VSS pins of both outputs. When the VDD bias voltage falls below VVDD_ON at device startup or below VVDD_OFF after startup, the VDD UVLO function holds the affected outputs low regardless of the state of the input pins (INA and INB). When the output stage of the driver is in an unbiased or undervoltage lockout state, the driver output is held low by an active clamp circuit, which limits the voltage rise on the driver output. In this case, the upper PMOS is blocked by RHi-Z, while the lower NMOS gate is connected to the driver output through RCLAMP. In this configuration, when no bias supply is available, the output is effectively clamped to the threshold voltage of the lower NMOS device, typically less than 1.5 V. The VDD UVLO protection has a hysteresis feature (VVDD_HYS). This hysteresis prevents chattering when the power supply has ground noise. This also allows the device to accept a small drop in bias voltage, which is bound to happen when the device starts switching and the operating current consumption suddenly increases. The UCC21521 also has internal undervoltage lockout (UVLO) protection on the input side. The device will not be active unless the voltage VCCI exceeds VVCCI_ON at startup. When this pin receives a voltage below VVCCI_OFF, it will stop passing the signal. Also, like the UVLO for VDD, there is hysteresis (VVCCI_HYS) to ensure stable operation.

6. Pin Description

7. Application Information

The UCC21521DWR effectively combines isolated and buffered drive functions. The flexible, versatile features of the UCC21521 (up to 18V VCCI and 25V VDDA/VDDB) allow the device to be used as a low-side, high-side, high-/low-side or half-bridge driver for MOSFETs, IGBTs or SiC MOSFETs. With integrated components, advanced protection features (UVLO, dead time, and enable), and optimized switching performance; the UCC21521 enables designers to Faster time to market for automotive and industrial applications.

8. Typical application

Circuit in Reference Design Using UCC21521DWR to Drive a Typical Half-Bridge Configuration guration which could be used in several popular power converter topologies such as synchronous buck, synchronous boost, half-bridge/full bridge isolated topologies, and 3-phase motor drive applications.