LV5980MX Datasheet, PDF (8/16 Pages) Sanyo Semicon Device – Low power consumption and high efficiency Step-down Switching Regulator

Detailed Description
LV5980MX
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 × 10^-6
[ms]
(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).
C4 × VtHIC _{C4 × 1.25}
THIC = _IHIC = _{1.8 × 10-6} [s]
(3)
The IC stops when the peak value of inductor current is higher
than overcurrent limit for 15 consecutive times.
ICL
IL
* The stop time defined by
external capacitor of C-HICCUP
C-HICCUP
SS
1.25V
THIC
FB
FB=1.02V
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.
PG
* FB ≥ 1.07V ⇒ High
No.A1980-8/16