Linear Technology Corporation introduces high-efficiency, four-output synchronous single-chip step-down switching regulators with up to 42V input

     Linear Technology Corporation introduces the LT8602, a 42V input, high-efficiency, four-output synchronous single-chip step-down switching regulator. The LT8602 comes in a heat-resistant enhanced 40-lead 6mm x 6mm QFN package. Three temperature grade versions are available, with extended E and Industrial I versions operating in the -40 °C to 125°C (junction temperature) range.

     The device's 4-channel design integrates two high voltage 2.5A and 1.5A channels and two lower voltage 1.8A channels to provide four independent outputs, which can deliver voltages as low as 0.8V. Its synchronous rectification topology provides up to 93% efficiency, while Burst Mode® operation keeps static currents below 30µA (all channels) without load backup, making the device ideal for systems that are always on. For noise-sensitive applications, the LT8602 operates in its pulse jump mode to minimize switching noise and meet CISPR25 Class 5 EMI requirements. The switching frequency can be set in the range of 250kHz to 2.2MHz, and can be synchronized in this range.

     The LT8602's 6ns minimum turn-on time allows for a step down conversion from 16VIN to 0.8VOUT and a switch at 2MHz, enabling designers to avoid critical noise sensitive bands such as AM radio while achieving a very compact solution. The device's 3V to 42V input voltage range makes it ideal for automotive applications, which must be regulated in cold start and vehicle start-stop situations as well as minimum input voltage drops to 3V and drop-off transients exceeding 40V.

     Each channel of the LT8602 maintains a minimum low-voltage differential voltage of only 200mV (at 1A) under all conditions, enabling the device to perform well in situations such as cold car start-up. The programmable power-on reset function and power good indicator for each channel ensure the overall reliability of the system. The LT8602's 40-lead heat-resistant enhanced 6mm x 6mm QFN package and high switching frequency allow for the use of small external inductors and capacitors, providing a high thermal efficiency solution with a compact plate area.

     The LT8602 features four internal up-tube and down-tube high-efficiency power switches that integrate the necessary boost diodes, oscillators, control and logic circuits in a single chip. Channels 1 and 3 switch at 180° reverse-phase relative to channels 2 and 4, reducing output ripple. Each channel has a separate input, increasing the flexibility of the design, but most applications will run two low-voltage channels directly with two high-voltage channels to provide a very simple high-frequency four-output design.

     Low Ripple burst mode operation maintains high efficiency at low output currents while keeping the output ripple below 15mVP-P. A unique design approach and the latest high-speed processes achieve high efficiency over a wide range of input voltages, and the LT8602's current mode topology enables fast transient response and excellent loop stability. Other features include internal compensation, good marking of the power supply, soft start/tracking of the output, and short circuit and overheat protection.