Power

High voltage synchronous buck-boost converter

28th November 2018
Alex Lynn

The TPS5516x-Q1 family of devices from Texas Instruments is a high-voltage synchronous buck-boost DC/DC converter. The device provides a stable power-supply output from a wide varying input-power supply such as an automotive car battery. The buck-boost overlap control ensures automatic transition between step-down and step-up mode with optimal efficiency. 

The TPS55165-Q1 output voltage can be set to a fixed level of five or 12V. The TPS55160-Q1 and TPS55162-Q1 devices have a configurable output voltage ranging from 5.7V to 9V that is set by an external resistive divider.

Output currents can be as high as one amp for a normal car battery voltage, and can be maintained at 0.4 A for lower input voltages, such as those for common battery-cranking profiles. The buck-boost converter is based on a fixed-frequency, pulse-width-modulation (PWM) control circuit using synchronous rectification to obtain maximum efficiency. The switching frequency is set to 2 MHz (typical) which allows for the usage of a small inductor that uses less board space.

A selectable spread-spectrum option (TPS55160-Q1 and TPS55165-Q1) helps reduce radiated electromagnetic interference (EMI). Internal loop compensation eliminates the need for external compensation components. In low-power mode (TPS55160-Q1 and TPS55165-Q1), the device achieves a quiescent current of less than 15µA which allows an automotive electronic control unit (ECU) to stay in standby mode (for example, listen-to-CAN mode) while achieving OEM quiescent-current requirements.

The low-power mode can be disabled which forces the converter to operate in full continuous mode at a fixed switching frequency of 2MHz (typical) for the entire load-current range. The maximum average current in the inductor is limited to a typical value of 2A.

The converter can be disabled to minimise battery drain. Furthermore, the device offers a power-good (PG) pin to indicate when the output rail is less than the specified tolerance. The device also has a power-latch function to allow an external microcontroller unit (MCU) to keep the output voltage available for as long as needed.

The device is available in a 20-pin HTSSOP PowerPAD package.

To find out more, click here.

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