Milpitas, Calif. - Touting a step improvement in power management for 14- and 42-volt automotive systems as well as industrial and other high-voltage applications, Linear Technology Corp.'s LT1976 is a 1.5-amp, 200-kHz monolithic buck switching regulator with a quiescent current of 100 micro-amps, which the company bills as unique for regulators of this type.
The LT1976, built around a proprietary high-voltage process, contains a 200-kHz oscillator and blocks that provide slope compensation, burst-mode detection, foldback detection and soft-start, as well as undervoltage lockout. It also includes complete driver circuitry, including a 1.5-A, 200-milliohm switch. These attributes, combined with burst-mode operation at low currents, achieves 80 to 90 percent chip efficiency in the 100-mA to 1-A load current range over a wide input voltage. The regulator's current-mode (vs. voltage-fed) topology derives fast transient response and optimizes loop stability, the company said. Supporting circuitry maintains peak switch current over the full duty cycle range.
The quiescent operating current of this bipolar device, which works from a 3- to 60-V input, is perhaps a tenth that of high-voltage step-down regulators, Armstrong said. He cited a savings of 40 to 50 cents on transient-suppressor circuitry that otherwise would be required for 36-V-rated parts in each of the car's MCU subsystems.
Withstanding the rigors of automotive environments, this chip can provide a regulated output down to about 3.5 V during cold-crank conditions. Other features include capability for external synchronization.
The LT1976 comes in a 16-pin TSSOP with exposed lead frame for maintaining low thermal resistance, and is rated for operation over -40 degrees C to 125 degrees C. It is priced at $4 each in lots of 1,000.
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