PWM Controller suited for DC/DC power converters.

Press Release Summary:

Low-profile (1 mm) 6-pin ThinSOT(TM) PWM LTC3803 current mode DC/DC controller works with flyback power supplies with 1-25+ W of output power. With adjustable slope compensation and 40 µA start-up current, product offers integrated soft-start function and can be powered with inputs from 10-100 V through resistor. Unit operates at constant 200 kHz frequency, provides ±1.5% output voltage accuracy, and has 100 mV current sense threshold.

Original Press Release:

ThinSOT PWM Controller Provides Sophisticated Control Functions for DC/DC Power Converters with up to 25W of Output Power

MILPITAS, CA - September 16, 2003 - Linear Technology Corporation introduces the LTC3803, a 6-pin ThinSOT(TM) PWM current mode DC/DC controller that reduces the size and complexity of flyback power supplies with 1W to over 25W of output power. With adjustable slope compensation, an LTC3803-based power supply achieves fast transient response with minimum output capacitance. Furthermore, with ultralow 40uA start-up current, the IC allows the use of a high-value input resistor and a low-value capacitor for low power dissipation and quick power supply start-up. An integrated soft-start function reduces inrush current, reducing output voltage overshoot. The LTC3803 can be powered with inputs from 10V to 100V through a resistor due to the IC's very low start-up current. The micro power hysteretic start-up circuit uses an internal Zener clamp to protect the part from input over voltage. The LTC3803 has applications in isolated and non-isolated 48V telecom, 42V and 12V automotive, ADSL, SLIC, and Power-over-Ethernet applications.

The LTC3803 operates at a constant 200kHz frequency and is optimized for driving 6V-rated N-channel MOSFETs in high input voltage applications. The ground-referenced current sensing allows LTC3803-based converters to accept any input voltage above 10V. Constant frequency operation is maintained down to very light loads, resulting in less low frequency noise generation over a wide range of load currents. The LTC3803 provides ±1.5% output voltage accuracy and consumes only 240uA of quiescent current. The 100mV current sense threshold allows the use of very small current sense resistors even at high power levels, and also helps maintain high efficiency.

The LTC3803 is rated for operation from -40°C to 85°C. Pricing starts at $1.40 each in 1,000-piece quantities.

Summary of Features: LTC3803

VIN and VOUT Limited Only by External Components

Adjustable Slope Compensation

Internal Soft-Start

Constant Frequency 200kHz Operation

±1.5% Reference Accuracy

Micropower Start-Up Current

Low Profile (1mm) ThinSOT Package

Company Background

Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include operational, instrumentation and audio amplifiers; voltage regulators, power management devices, DC-DC converters and voltage references; comparators; monolithic filters; communications interface circuits; one-chip data acquisition sub-systems; pulse-width modulators and sample-and-hold devices; and high frequency devices. Applications for Linear Technology's high performance circuits include wireless and broadband telecommunications infrastructure, cellular telephones, networking products and satellite systems, notebook and desk top computers, computer peripherals, video/multimedia, industrial and medical instrumentation, automotive electronics, factory automation, process control, military and space systems, and high-end consumer products including digital cameras, MP3 players and other electronic products.

Note: LT, AND LTC are registered trademarks of Linear Technology Corp.


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