L6731B

Summary description

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Summary description

The controller is an integrated circuit realized in BCD5 (BiCMOS-DMOS, version 5) fabrication

that provides complete control logic and protection for high performance step-down DC-DC and

niPOL converters.

It is designed to drive N-Channel MOSFETs in a synchronous rectified buck topology. The

output voltage of the converter can be precisely regulated down to 600mV with a maximum

tolerance of ±0.8%. If an external reference is used, it will be trasferred divided by 2 to the N.I.

input of the error-amplifier, in accordance to the DDR memory specifications.

An internal resistor divider and a voltage buffer allow to achieve an accuracy of 1% on both Vtt

and Vttref. It's possibile to provide an external reference from 0V to 2.5V in order to meet the

specification for DDRI and DDRII. The input voltage can range from 1.8V to 14V, while the

supply voltage can range from 4.5V to 14V. High peak current gate drivers provide for fast

switching to the external power section, and the output current can be in excess of 20A.

100ns making possible conversions with very low duty cycle at high switching frequency. The

device provides voltage-mode control that includes a selectable frequency oscillator (250KHz

or 500KHz).

The error amplifier features a 10MHz gain-bandwidth-product and 5V/µs slew-rate that permits

to realize high converter bandwidth for fast transient response. The device monitors the current

current sensing resistor and guaranteeing an effective over-current-protection in all the

application conditions.

When necessary, two different current limit protections can be externally set through two

external resistors. During the soft-start phase a constant current protection is provided while

after the soft-start the device enters in hiccup mode in case of over-current. The converter can

always sink current. Other features are Power-Good, not latched over-voltage-protection, feed-

back disconnection and thermal shutdown. The HTSSOP16 package allows the realization of

really compact DC/DC converters.