Switching Regulator enhances automotive and industrial applications
Published: 9 July 2012 - Michelle Winny
A quad 1A output, 40V step-down switching regulator has been released by Linear Technology Corporation with 100 percent duty cycle operation.
The new device is the LT3504 featuring a 3.2V to 40V input voltage range making it ideal for automotive and industrial applications that require multiple outputs.
The internal 1.5A switches are capable of delivering up to 1A of continuous output current per channel to voltages as low as 0.8V. An interesting design aspect includes an onboard boost regulator, enabling each channel to operate at 100 percent duty cycle, even with input voltage as low as 3.2V.
This architecture makes the device well suited for applications requiring continuous output regulation, such as automotive cold-crank and stop-start scenarios.
Switching frequency is user-programmable from 250kHz to 2.2MHz and synchronisable throughout the range, enabling users to optimise efficiency while avoiding critical noise-sensitive frequency bands.
The well considered mix of its 28-lead 4mm by 5mm QFN and high switching frequency keeps external inductors and capacitors small, providing a compact, thermally efficient footprint for multiple output applications.
This device utilises four internal 1.5A switches for the step-down conversion and a 220mA switch for the internal boost circuit, with the necessary oscillator, control and logic circuitry integrated into a single die.
Special design techniques and a new high voltage process deliver efficiencies up to 88 percent over a wide input voltage range, while the current mode topology enables fast transient response and excellent loop stability.
Anti-phase switching reduces input ripple and robust short-circuit protection enhances system reliability.
Other features include output voltage tracking, programmable undervoltage lockout and a power good pin to indicate when all outputs are in regulation.