Benefits of UCC5880 over UCC587x

The UCC5880-Q1 device is an isolated, highly configurable adjustable slew rate gate driver. One element that makes UCC5880 very useful in high power EV/HEV applications is it’s SPI based device configurability, verification, and diagnostics.

Although the SPI communication provides a lot of flexibility for the system, some applications do not require the complexity of SPI. Customers who are not familiar with SPI may appreciate its benefits, but when getting started with this new driver, may want to do a simple evaluation without spending time and resources developing the software. The UCC5880-Q1 device can support this as it can be used without SPI communication for initial evaluation of the device

Using this functionality, the engineer can evaluate basic driver performance like drive strength, switching losses with power modules, adjustable gate drive, short circuit protection, etc. The user will be able to speed up the evaluation process since there is no requirement to develop any new code or even connect to a computer.

High Level Specification Comparison:

Pinout & Application level Improvements:

                                 UCC587x Application Diagram                                                                                UCC5880 Application Diagram

The UCC5880 has improved upon the previous UCC587x by optimizing the pinout/supply topology allowing lower pin count and a smaller package to 32 pin DFC package vs the 36 pin DWJ, achieving better performance and power density. Below is a table depicting the differences and similarities in the pinout and functionality of the devices.

UCC588x Pin/feature change vs UCC587x

Output Drive Improvements:

UCC5880 adds the variable gate drive feature with its new innovative output structure. UCC5880 has a dual-split output structure compared to a simple split output structure of UCC587x. This then gives the device the ability to use 3 different combinations for turn on and turn off. The driver can also switch between the different drive strengths on the fly using SPI commands or an external control with the GDx pins. This gives the user the ability to control the drive strength for different load conditions, ultimately leading to significant improvements to efficiency and EMC. Based on TI’s inverter testing, Adjustable Gate Drive gives an increased 2% efficiency gain.

                                                                                               UCC587x vs UCC5880 Output Stage Diagram                               

Programming Improvements:

UCC5880 enhances SPI communication requirements to increase flexibility and configurability to the SPI programming of the device.

Key changes to UCC5880:

1. Starts up in active mode – Read registers are always available, all startup BISTs happen during transition to active mode and the driver can be evaluated without software
2. Reduced number of registers from 31 to 23 - Increased efficiency for using configuration register bits to optimize programming and increase configuration speed
3. Requires commands to enable/disable addressing mode
4. Requires command to enable/disable configuration mode

ADC Improvements:

UCC5880 adds continuous mode sampling to allow digitization without PWM toggle for easier start-up diagnostics. ADC channel bits can be used to include measurements in round robin when PWM is static high or low. VCC2 and DESAT nodes have also been added to the MUX and can be measured and reported in the ADC register.

UCC5880 also boasts increased ADC configurability and accuracy. The table below shows the total unadjusted error based on the improved datasheet specifications.

UCC5880 ADC Accuracy Results

EMC Robustness Improvements:

In a typical inverter system, noise can couple into the device through Switch node noise, ground loops, noise from other systems, hole in shield walls, DC bus bars, etc. Therefore, it is important to choose a robust and reliable gate driver. UCC5880 has significant improvements over UCC587x in regards to robustness.

Key Lane Improvements:

1. Internal LDO’s for communication lanes that were previously decoupled in UCC587x, are now completely internal in UCC5880, eliminating a possible noise coupling path.
2. UCC5880’s communication method is designed to optimize common mode rejection. This translates to increased immunity on the communication lanes which leads to improvements in GNTI, CMTI and Radiated Noise.
3. CMTI rating increase from 100V/ns to 150V/ns for UCC5880.

Device Evaluation Improvements:

A major improvement of UCC5880 over UCC587x is the ability for UCC5880 to drive the power stage without the need for SPI control or communication. This prevents the user from needing to design any software for simple evaluation of the driver for Double Pulse, which directly results in a shorter development cycle time. To learn more about using UCC5880 without SPI, please see the FAQ here.

UCC5880 adds a new 16- bit SPITEST register which may be written with any data pattern. The read back of these contents can be used to test SPI engine health during diagnostics cycles and SPI test routines from the controller.