LV5980MX

No.A1980-8/16

Detailed Description

Power-save Feature

The LV5980MX has Power-saving feature to enhance efficiency when the load is light.

By shutting down unnecessary circuits, operating current of the IC is minimized and high efficiency is realized.

Output Voltage Setting

Output voltage (VOUT) is configurable by the resistance R3 between VOUT and FB and the R2 between FB and GND.

VOUT is given by the following equation (1).

VOUT = (1 +

R3

R2 ) × VREF = (1 +

R3

R2 ) × 1.235 [V]

(1)

Soft Start

Soft start time (TSS) is configurable by the capacitor (C5) between SS and GND. The setting value of TSS is given by the

equation (2).

TSS = C5 ×

VREF

ISS

= C5

×

1.235

1.8

(2)

Power Good

FB constantly monitors VOUT. When FB voltage is lower than 1.02V, PG is pulled down to Low. PG comparator has

hysteresis of 50mV. Because PG is open-drain output, you can connect other ICs with PG to realize wired-or with other

ICs.

Hiccup Over Current Protection

Over current limit (ICL) is set to 4.7A in the IC. When the peak value of inductor current is higher than 4.7A for 15

consecutive times, the protection deems it as over current and stops the IC. Stop period (THIC) is defined by the external

capacitor of the C-HICCUP. When C-HICCUP is about 1.25V, the IC starts up. Regardless of a status; whether it starts up

or SS charge, once over current is detected, the IC stops again and when the protection does not detect over current status,

the IC starts up again. The setting value of THIC is given by the equation (3).

THIC =

C4

× VtHIC

IHIC

=

C4

× 1.25

1.8

(3)

ICL

IL

C-HICCUP

SS

1.25V

FB=1.02V

THIC

FB

PG

The IC stops when the peak value of inductor current is higher

than overcurrent limit for 15 consecutive times.

* The stop time defined by

external capacitor of C-HICCUP

The IC starts up when C-HICCUP is 1.25V

•The IC stops when overcurrent is detected.

•The IC starts up again if no overcurrent is detected.

* FB

≥ 1.07V ⇒ High