L6731D

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 600 mV with a maximum

tolerance of ±0.8 %. If an external reference is used, it will be transferred 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 possible to provide an external reference from 0V to 2.5 V in order to meet

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

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

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

than 100 ns making possible conversions with very low duty cycle at high switching

frequency. The device provides voltage-mode control that includes a selectable frequency

oscillator (250 kHz or 500 kHz).

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

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

the need for a 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.