Step-down Controller Features Start-up Regulator

Apr 6, 2005 11:38 AM

Linear Technology’s LT3800 is a current-mode, high-voltage step-down controller that integrates a start up regulator, which allows the chip to operate directly off of 4-V to 60-V supplies. Designed to offer tight line and load regulation and fast transient response, the controller generates an output voltage ranging from 1.23 V to 36 V at currents up to 10 A.

By driving N-channel MOSFETs synchronously with maximum gate-source “ON” voltage, this controller operates at 94% efficiency while converting 60-V input to 12 V at 36-W output. Moreover, the LT3800 incorporates Burst Mode operation, which reduces no load quiescent current to less than 100 µA, a feature required in automotive maintenance power supplies. The LT3800 has applications in 12-V and 42-V automotive, 48-V telecom supplies, avionic and industrial control systems.

The LT3800 operates at a 200-kHz fixed frequency. The device employs a reverse-current inhibit feature to increase efficiency during light loads. This feature disables the synchronous switch if inductor current approaches zero. Another feature of the LT3800 is its adaptive non-overlap control. Non-overlap control maintains a constant dead time, preventing shoot-through switch currents independent of the type, size or operating conditions of the external MOSFET switches.

The LT3800 is offered in a 16-pin thermally enhanced TSSOP. In quantities of 1000, unit pricing starts at $3.10.

For more information, visit www.linear.com.

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