Texas Instruments’ Bias Supply Module is Aimed at EV Applications
The isolated, 1.5W DC/DC device employs a tiny internal planar transformer to cut power solution sizes in half for EVS and HEVs.
The UCC14240-Q1 from Texas Instruments (TI) works with inputs ranging from 21V to 27V and is purposed to power IGBT or SiC gate drivers.
Simplified application diagram. Image courtesy of datasheet
A vital goal in EV design is to reduce the weight of the powertrain, the heaviest part of the vehicle. One of the means to this goal is the adaptation of a distributed power architecture, with every isolated gate driver served by a dedicated bias supply. This architecture also improves safety by reducing single-point failures, because even if one bias supply fails, the others, and their associated gate drivers, are unaffected. This allows the vehicle to remain operational until repairs can be safely effected.
Distributed Architectures for Next Generation of EVs
TI’s John Stevens notes that traditional EV architecture calls for a single transformer and bias supply for all of the powertrain’s gate drivers. This model is susceptible to EMI and makes it difficult to regulate the voltage at each point of the power network.
The size and weight of flybacks and push-pull controllers prevent their deployment in lightweight distributed architectures. What the UCC14240-Q1 achieves is the integration of the far smaller planner transformer and the other components into one small, light modular package. The transformer further offers a 3.5pF primary-to-secondary capacitance, which contributes to common-mode-transient immunity (CMTI) of 150 V/ns, an important feature in the dense, fast-switching EV arena.
The integration of primary-side and secondary-side control with isolation allows the device to achieve ±1.3% regulation of its 18V to 25V output.
Distributed architecture for EV/HEV traction inverters. Image courtesy of TI
EV power systems going forward will increasingly employ SiC and GaN power switches for smaller power supplies of greater efficiencies, but these vital new technologies do require the more tightly regulated gate-driver voltages that the UCC14240-Q1 offers. This is especially true because systems employing these advanced semiconductors will switch at higher voltages and at far faster speeds.
Important UCC14240-Q1 Features
The module offers:
- Input under-voltage and over-voltage lockout
- Over-temperature shutdown
- Soft-start timing
- Adjustable, isolated positive and negative output voltages
- VIN quiescent current, disabled: 500µA
- VIN operating current, no load: 8mA
- VIN operating current, full load: 135mA
- Junction-to-ambient thermal resistance: 52.3 °C/W
- Junction-to-case (top) thermal resistance: 28.5 °C/W
- Junction-to-board thermal resistance: 25.9 °C/W
The datasheet supplies complete information.
In addition to EV and HEV power train systems, the UCC14240-Q1 can be applied to:
- EV charging stations
- On-board charging
- Power grid infrastructure
- Robot servo drives
- The UCC14240-Q1 operates over a temperature range -40 to +125℃ or 150℃, depending on the version
- The unit is available in an SSOP package and takes up 12.83mm x 7.50mm (plus gull wings) of board space with a maximum height of only 3.55mm
Regulatory and Safety
3000-VRMS isolation for 1 minute as per UL 1577.
UL certification per:
○ IEC 60950-1
○ IEC 62368-1
○ IEC 60601-1
○ Human-body model (HBM) ±2kV
○ Charged-device model (CDM) ±500V