Electronic Design

Step-Down Switching Regulator Provides 60-V Input Transient Protection

The LT3682 step-down switching regulator from Linear Technology provides input transient protection up to 60 V. Its Burst Mode operation keeps quiescent current under 75 µA in no-load standby conditions. With its 60-V transient ride through, its 3.6- to 36-V input voltage range suits the LT3682 for load dump and cold-crank conditions commonly found in automotive applications.

The regulator’s internal switch can deliver up to 1 A of continuous output current to voltages as low as 0.8 V. Its Burst Mode operation offers ultra-low quiescent current, which is well suited for applications like automotive or telecom systems that demand always-on operation and optimum battery life.

The switching frequency is user-programmable from 250 kHz to 2.2 MHz, so designers can optimize efficiency while avoiding critical noise-sensitive frequency bands. The combination of this switching frequency and its 10-pin, 3- by 4-mm DFN-14 (dual flat no-lead) package keeps external inductors and capacitors small, providing a very compact, thermally efficient footprint.

Furthermore, the LT3682 uses a high-efficiency, 1.5-A, 480-mΩ switch, with the boost diode, oscillator, control, and logic circuitry integrated into a single die. Its low-ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 15 mV p-p.

Special design techniques and a new high-voltage process enable high efficiency over a wide input voltage range while its current-mode topology enables fast transient response and excellent loop stability, according to Linear Technology. Other features include external synchronization (from 300 kHz to 2.2 MHz), a power-good flag, and soft-start capability.

Pricing for the LT3682EDE starts at $2.95 each in 1000-piece quantities. The LT3682IDE, which is tested and guaranteed to operate from a –40°C to 125°C operating junction temperature, costs $3.95 each in 1000-piece quantities. All versions are available from stock.

Linear Technology


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