Components

3A AEC-Q100 Switching Regulator can Operate from 24V Battery

The STMicroelectronics A7987 automotive switching regulator features a wide input voltage range that allows use in trucks and buses. An adjustable output voltage ensures flexibility and stable performance to power the numerous voltage rails in automotive applications including body infotainment and telematics.

With a maximum input voltage of 61V, the A7987 can operate from a 24V battery in a conventional or hybrid/electric vehicle and support a regulated output despite disturbances such as load-dump. Its output is adjustable from 0.8V up to the input voltage, with low dropout, and it can deliver up to 3A for a wide variety of loads from lighting to logic.

The wide input voltage range and the almost 100% duty cycle capability meet the fail-safe specifications for industrial systems.

Related: Peripheral Sensor Interface 5 Reduces Automotive Sensor System Costs

The embedded switch-over feature on the VBIAS pin maximizes the efficiency at light load. The adjustable current limitation, designed to select the inductor RMS current in accordance with the nominal output current.

A high switching frequency capability helps make the application compact.

Current limit and switching frequency are set with external pulldown resistors. The switching frequency can be set at up to 1.5MHz. This setting of the current limit and frequency allows the creation of compact power modules by optimizing the output-inductor size.

Pulse-by-pulse current sensing with digital frequency foldback in short-circuit reduces the stress on power components to improve reliability. Thermal protection is built-in along with shutdown and auto-recovery to reduce the reliance on external intervention.

The A7987 embeds a low-resistance N-channel power MOSFET. At light load, pulse skipping maintains output regulation.

Bias-voltage input with integrated switchover allows the powering analog circuitry from an external source for optimum efficiency.

A synchronization pin allows the coexistence of five regulators by switching out of phase to avoid noise effects and reducing the RMS current flowing in the input capacitor. An Enable pin and a Power-Good indicator with adjustable delay allow power-up sequencing.

Also, an adjustable soft-start function limits inrush current.

Key Features
  • 3A dc output current
  • 4.5V to 61V operating input voltage
  • RDS(on) = 250mΩ typ.
  • Adjustable fsw (250kHz to 1.5MHz)
  • Low IQ-SHD (11µA typ. from VIN)
  • Low IQ (1mA typ. – VIN 24V – VOUT 3.3V)
  • Output voltage adjustable from 0.8V to VIN
  • Synchronization
  • Adjustable soft-start time
  • Adjustable current limitation
  • Low-dropout operation
  • VBIAS improves efficiency at light load
  • PGOOD open collector output
  • Output voltage sequencing
  • Digital frequency fold-back in short-circuit
  • Auto recovery thermal shutdown
  • Qualified following AEC-Q100 requirements

AEC-Q100 certified, the A7987 switching regulator is now in production. It comes in a 5mm x 6.4mm HTSSOP16 exposed-pad package, priced from $2.00 for orders of 1000 pieces.

STEVAL-ISA207V1 evaluation board

ST also released the STEVAL-ISA207V1 evaluation board, available now from the company’s website or its distributors, to accelerate new projects using the A7987. The STEVAL-ISA207V1 evaluation board is a step-down switching power supply based on the A7987 regulator in an HTSSOP16 package. It is designed for automotive system battery-powered applications.

STMicroelectronics NV
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