Linear Technology Introduces Synchronous Step-Down DC/DC Controller

Photocoupler

Linear Technology Corporation has launched the LTC3869/-2, a dual-output high-efficiency synchronous step-down DC/DC controller that achieves up to 95% efficiency. This device is designed to deliver excellent current balance when operating in parallel, with a maximum mismatch of just 2mV and a current imbalance of less than ±4% between channels during both steady-state and transient conditions. Its wide input voltage range—ranging from 4V to 38V—makes it suitable for a variety of applications, including intermediate bus voltages and various battery chemistries.

The LTC3869/-2 features a powerful 1.1Ω internal gate driver, which helps reduce switching losses and supports high-power external MOSFETs to deliver up to 25A per channel across an output voltage range of 0.6V to 12.5V. The controller ensures stable and jitter-free performance, even when switching pulses span multiple phases, making it ideal for noise-sensitive environments such as ASIC and FPGA power supplies, network servers, and automotive systems.

With a minimum turn-on time of only 90ns, the LTC3869/-2 is well-suited for high-frequency, high-step-down ratio applications where space is limited. It includes current mode control, along with tracking and sequencing capabilities to optimize power-up and power-down sequences for multiple power rails. The device operates using full N-channel MOSFETs and maintains an output accuracy of ±1% over a broad temperature range from -40°C to 125°C.

The LTC3869/-2 offers flexible current sensing options: it can use the voltage drop across the output inductor (DCR) for maximum efficiency or a sense resistor for more precise measurements. The fixed operating frequency can be set between 250kHz and 780kHz, or synchronized to an external clock via an internal PLL. Additional features include a built-in LDO for IC power, programmable soft-start, power good signals, and external VCC control, making it a versatile solution for complex power management needs.

The LTC3869 is available in a compact 4mm x 5mm QFN package, while the LTC3869-2 comes in a SSOP-28 package. Both versions are compatible with the LTC3850 pinout, offering design flexibility. With a unit price of $2.65 for 1,000 pieces, they are readily available from stock, making them a cost-effective choice for engineers looking for reliable and high-performance power solutions.