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It also includes monitoring junction temperatures, and the control device should be immune to radiated and conducted noise while not contributing to emissions. The device should also be able to manage power sequencing during startup and shutdown, it should withstand large voltage transients and temperature extremes. Historically, many PMICs have not possessed the necessary power to handle these modern systems and microprocessors. Any solution to satisfy the automotive power management IC design constraints as already outlined must combine a high level of integration, including high-current switching regulators and LDOs, wide temperature range of operation, power sequencing and dynamic I2C control of key parameters with hard-to-do functional blocks. Furthermore, a device with high switching frequency reduces the size of external components and ceramic capacitors reduce output ripple. This low ripple combines with accurate, fast response regulators to satisfy demanding voltage tolerances of 45nm type processors. Such power ICs must also be capable of meeting the rigorous automotive environment including radiated emission suppression, although the input voltage is typically a preregulated 5V or 3.3V rail off the system or battery voltage. A high power, power management solution The LTC3676/-1 are complete power management solutions for Freescale i.MX6 processors, ARM based processors and other advanced portable microprocessor systems. The chip contain four synchronous step-down DC/DC converters at up to 2.5A each for core, memory, I/O and system on-chip (SoC) rails plus three 300mA linear regulators for low noise analog supplies. It configures a 1.5A buck regulator for source/sink and tracking operation to support DDR memory termination and also adds a VTTR reference output for DDR. These two pin features replace the LDO4 enable pin and feedback pins of the LTC3676. LDO4 is still programmable by I2C. Supporting the multiple regulators is a highly configurable power sequencing capability, dynamic output voltage scaling, a pushbutton interface controller, plus regulator control via an I2C interface with extensive status and fault reporting via an interrupt output. The LTC3676 supports i.MX6, PXA and OMAP processors with eight independent rails at appropriate power levels with dynamic control and sequencing. Other features include interface signals such as the VSTB pin that toggles between programmed run and standby output voltages on up to four rails simultaneously. Delivered in a 40-pin 6x6x0.75mm exposed pad QFN package, this integrated power management solution for application processors can solve the automotive infotainment system design challenges outlined above. The LTC3676HUJ PMIC is available in a high temperature (H-Grade) option with a junction temperature rating from -40°C to +150°C, easily satisfying the high temperature automotive operating requirement. The IC includes a thermal warning flag and interrupt specifically for junction temperature monitoring and also includes a hard thermal shutdown for reliable protection of the hardware, should power dissipation be mismanaged, or in the event of a severe fault condition. www.electronics-eetimes.com Electronic Engineering Times Europe November 2013 25


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