L6722

4 Device description

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Device description

L6722 is multi-phase PWM controller with embedded high current drivers that provides

complete control logic and protections for a high performance step-down DC-DC voltage

regulator. Multi-phase buck is the simplest and most cost-effective topology employable to

satisfy the increasing current demand of the modern high current DC/DC converters and POLs

requirements. It allows distributing equally load and power between the phases using smaller,

cheaper and most common external power mosfets and inductors. Moreover, thanks to the

equal phase-shift between each phase, the input and output capacitor count results in being

reduced. Phase interleaving causes in fact input rms current and output ripple voltage reduction

and show an effective output switching frequency increase: the 100kHz free-running frequency

per phase, externally adjustable through a resistor, results multiplied on the output by the

number of phases.

The device comes with a fixed 0.8V reference that guarantee the output regulated voltage to be

within

FBG. OFFSET may be added to the main reference so allowing the device to be tested for

margining during the system production. In addition, droop function may be enabled to perform

precise voltage positioning according to the delivered current.

SS is performed by increasing the reference in 2048 clock cycles in closed loop regulation.

L6722 provides a complete set of protections to avoid damaging the load in any operative and

non-operative conditions:

●

Over-Voltage protection protects the load from dangerous over stress latching immediately

the lower driver ON and driving high the FAULT pin.

●

Preliminary OVP protection also allows the device to protect the load from dangerous OVP

when VCC is not above the UVLO threshold.

●

UVP protection latches the device and drives high the FAULT pin.

●

Over-Current protection is provided with an OC threshold for each phase; when set, it

causes the device to enter in constant current mode until the latched UVP.

●

Low-Side-Less start-up allows the device to perform soft-start over pre-biased output

avoiding dangerous current return through the main inductors as well as negative spike at

the load side and allowing the device to work in redundant systems.

A compact VFQFPN36 package with exposed thermal pad allows dissipating the power to drive

the external mosfet through the system board.