L5988D 查看數據表（PDF） - STMicroelectronics

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L5988D

4 A continuous (more than 5 A pulsed) step-down switching regulator with synchronous rectification

STMicroelectronics 

Description

1

Description

L5988D

The L5988D is a monolithic step down power switching regulator able to deliver a

continuous output current of 4 A to the load in most of the application conditions limited only

by the thermal performance. The device is able to deliver more than 5 A to the load for a

maximum time which is dependent on the thermal impedance of the system and the specific

operating conditions).

The input voltage can range from 2.9 V to 18 V. The device is capable of 100% duty cycle

operation thanks to the embedded high side PMOS switch which doesn’t need external

bootstrap capacitor to be driven.

The internal switching frequency is adjustable by external resistor and can be set

continuously from 100 kHz to 1 MHz. The L5988D can also be synchronized to an external

frequency signal driven to the SYNCH pin I/O pin.

The multifunction UOS pin allows to set-up properly the additional embedded features

depending on the value of the voltage level.

 U (UVLO): two UVLO thresholds can be selected to match the 3.3 V and 5 V or 12 V

input buses

 O (OVP): latched or not latched OVP protection selectable. In latched mode the

switching activity is interrupted until an UVLO or INH event happens

 S (SINK): the sink capability is always disabled during soft-start time to support pre-

biased output voltage. Afterwards the sink capability can be enabled or not depending

on the voltage set on the multifunction pin.

During soft-start phase a constant current protection is active to deliver extra current

necessary to load the output capacitor. The current limit protection is achieved by sensing

the current flowing in both embedded switches to assure an effective protection even at

extreme duty cycle operations. Finished the soft-start phase the current protection feature

triggers the “HICCUP” mode forcing the soft-start capacitor to be discharged and recharged.

The current thresholds of both switches can be adjusted in tracking by using an external

resistor to dimension the current protection accordingly to the local application.

The soft-start time is based on a constant current charge of an external capacitor. As a

consequence the time can be set accordingly to the value of the output capacitor.

The latest smart power technology BCD6 (Bipolar-CMOS-DMOS version 6) features a low

resistance of the embedded switches (35 m typical for a NMOS, 50 m typical for a

PMOS), achieving high efficiency levels.

The HTSSOP16 package with exposed pad accomplishes low RthJA (40 °C/W), useful in

dissipating power internally generated during high output current / high frequency

operations.

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DocID15324 Rev 4

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