Synchronous buck-boost converter

30th August 2018
Posted By : Alex Lynn
Synchronous buck-boost converter

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 5.7 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 0.4A 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 2MHz (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 minimize 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.

Features

  • Qualified for Automotive Applications
  • AEC-Q100 Qualified with the Following Results:
    • Device Temperature Grade 1: -40 to +125°C Ambient Operating Temperature
    • Device HBM ESD Classification Level two
    • Device CDM ESD Classification Level C4B
  • 2 to 36V Input Voltage Range for VOUT = 5V
  • 5V or 12V Fixed Output Voltage (TPS55165-Q1)
  • Adjustable Output Voltage Options from 5.7 to 9V (TPS55160-Q1 and TPS55162-Q1)
  • Up to 85% Efficiency
  • 1A Output Current for VOUT = 5V and VIN ≥ 5.3V
  • 0.8A Output Current for VOUT = 5V and VIN ≥ 3.8V
  • 0.4A Output Current for VOUT = 5V and VIN ≥ 2.3V
  • Automatic Transition Between Step-Down and Step-Up Mode
  • Low-Power Mode for Improved Efficiency at Light Load Conditions (TPS55160-Q1 and 
    TPS55165-Q1)
  • Device Quiescent Current Less than 15µA in Low-Power Mode (TPS55160-Q1 and 
    TPS55165-Q1)
  • Device Shutdown Current Less than 3µA
  • Forced Fixed-Frequency Operation at 2MHz
  • Selectable Spread Spectrum (TPS55160-Q1 and TPS55165-Q1)
  • Wake-up Through IGN With Power-Latch Function
  • Smart Power-Good Output With Configurable Delay Time
  • Overtemperature Protection and Output Overvoltage Protection
  • Available in Easy-to-Use 20-Pin HTSSOP PowerPAD™ Package

To find out more, click here


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