ST STEVAL-A6983IV1 User Manual

UM3476
User manual
Getting started with STEVAL-A6983IV1 evaluation board based on A6983I, 38 V,
10 W synchronous iso-buck converter for isolated applications
Introduction
The STEVAL-A6983IV1 is an evaluation board based on ST A6983I, 38 V, 10 W synchronous iso-buck converter designed for
isolated applications.
The primary output voltage can be accurately adjusted, whereas the isolated secondary output is derived by using a given
transformer ratio. No optocoupler is required. The primary sink capability up to -4.5 A (even during soft-start) allows a proper
energy transfer to the secondary side as well as enables a tracked soft-start of the secondary output. The control loop is based
on a peak current mode architecture and the device operates in forced PWM. The 390 ns blanking time filters oscillations,
generated by the transformer leakage inductance, making the solution more robust.
The compact QFN-16 3x3 mm package and the internal compensation of the A6983I help minimizing design complexity and
size.
The switching frequency can be programmed in the 200 kHz - 1 MHz range with optional spread spectrum for improved EMC.
The EN pin provides enable/disable functionality. The typical shutdown current is 2 uA when disabled. As soon as the EN pin is
pulled-up the device is enabled and the internal 1.3 ms soft start takes place. The A6983I features a power-good open collector
that monitors the FB voltage. Pulse by pulse current sensing on both power elements implements an effective constant current
protection and thermal shutdown prevents thermal run-away. Due to the primary reverse current limit, the secondary output is
protected against short-circuit events.
The evaluation board generates an isolated unregulated voltage and provides the possibility to use a postregulation to generate
a dual voltage (layout available on the bottom of the PCB, components not mounted).
Figure 1. STEVAL-A6983I
Notice: For dedicated assistance, submit a request through our online support portal at www.st.com/support.
UM3476 - Rev 1 - February 2025
www.st.com
For further information, contact your local STMicroelectronics sales office.