Application information

LNBH30

6/27

DocID023739 Rev 2

2

Application information

This IC has a built-in DC-DC step-up converter that, from a single source of typically 12 V,

below a fixed threshold (4.7 V typ.). The step-up converter is provided with a soft-start

function which reduces the in-rush current during startup. The SS time is internally fixed at

5 ms typ. to switch from 0 to 15 V.

2.1

Output current limit selection

The linear regulator current limit threshold can be set by an external resistor connected to

the ISEL pin. The resistor value defines the output current limit as per the following

equation:

where RSEL is the resistor connected between ISEL and GND expressed in kΩ and

2.2

Output voltage selection

The linear regulator channel output voltage level can be easily programmed in order to

accomplish application specific requirements, using 3 bits of the internal DATA register see

Section 7.1: "Write mode transmission" and Table 6: "Data (read/write register, register

address = 0x1)" for exact programmable values. Register writing is accessible via the I²C

bus.

2.3

COMP: boost capacitors and inductor

The DC-DC converter compensation loop can be optimized in order to properly work with

register (see COMP) can be set to “1” or “0” as follows:

COMP = 0 for electrolytic capacitors

COMP = 1 for ceramic capacitors

For recommended DC-DC capacitor and inductor values refer to Section 5: "Typical

application circuits" and to the BOM in Table 5: "Typical application circuit bill of material".

2.4

Diagnostic and protection functions

The LNBH30 has 5 diagnostic internal functions provided by the I²C bus, by reading 5 bits

on the status register (in read mode). All the diagnostic bits are, in normal operation, set to

LOW. Two diagnostic bits are dedicated to the overtemperature and overload protection

status (OTF and OLF) while the remaining 3 bits are dedicated to the output voltage level

(VMON), to external voltage source presence on the VOUT pin (PDO) and to the input

IMAX(typ.)= 13915

RSEL

1.111