1 Features

• AEC-Q100 qualified for automotive applications:

– Device temperature grade 1: –40⁰C to +125⁰C

– Device HBM classification Level 2: ±2kV

– Device CDM classification Level C4B: ±750V

• Functional Safety-Capable

– Documentation available to aid functional safety

system design

• Enables zero-power (< 5mW) standby

consumption

• Primary-side regulation (PSR) eliminates optical

coupler

• ±5% voltage regulation and current regulation

across line and load

• 700V start-up switch with 30V minimum start-up

voltage

• 83kHz maximum switching frequency enables low

stand-by power charger designs

• Resonant-ring valley-switching operation for

improved overall efficiency

• Frequency-dither to ease EMI compliance

• Clamped gate-drive output for MOSFET

• Over-voltage, low-line, and over-current protection

functions

• Programmable cable compensation

• SOIC-7 package

2 Applications

• Hybrid, electric and powertrain systems

• Traction inverter-high voltage redundant and

backup power Supplies

• On-board charger primary bias supplies

• DC/DC converter standby and auxiliary power

supplies

3 Description

The UCC28731-Q1 isolated-flyback power supply

controller provides constant-voltage (CV) and

constant-current (CC) output regulation without the

use of an optical coupler minimizing board area plus

BOM count for higher lifetime reliability. This device

processes information from the primary power switch

and an auxiliary flyback winding for precise regulation

of output voltage and current, hence the label PSR.

A minimum switching frequency of 32Hz facilitates

achieving less than 5mW of no-load power. An

internal 700V start-up switch, dynamically- controlled

operating states and a tailored modulation profile

support ultra-low stand-by power without sacrificing

start-up time. Control algorithms in the UCC28731-

Q1 allow operating efficiencies to meet or exceed

applicable standards. Discontinuous conduction mode

(DCM) operation with valley-switching reduces

switching losses. Modulation of the switching

frequency and primary current peak amplitude (FM

and AM) keeps the conversion efficiency high across

the entire load and line ranges.