Features
Designed for iso-buck topology
3.5 V to 38 V operating input voltage
Primary output voltage regulation / no optocoupler required
4.5 A source / sink peak primary current capability
Peak current mode architecture in forced PWM operation
390 ns blanking time
200 kHz to 1 MHz programmable switching frequency. Stable with low ESR
capacitor: min 2 μF
Internal compensation network
2 μA shutdown current
Internal soft-start
Enable
Overvoltage protection
Output voltage sequencing
Thermal protection
Optional spread spectrum for improved EMC
Power Good
Synchronization to external clock
QFN16 (3x3 mm) package

Applications
Isolated IGBT/SiC MOSFET gate drive supply
OBC (On-board charger) for HEV/EV
Electric traction systems

Description
The L6983I is a device specifically designed for isolated buck topology. 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 enabling 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 QFN16 3x3 mm package and the internal compensation of the L6983I
help minimize 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 μA 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 L6983I
features 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.