AN3115

Block diagram and pin function description

Doc ID 16830 Rev 3

5/28

1

Block diagram and pin function description

The internal blocks of the LNBH23L are described in the following paragraphs:

1.1

Step-up controller

The LNBH23L features a built-in step-up DC-DC converter that, from a single supply source

ranging from 8 V to 15 V, generates the voltages that allow the linear post-regulator to work

with minimum power dissipation. The external components of the DC-DC converter are

1.2

Pre-regulator block

This block includes a voltage reference connected to the BYP pin, an undervoltage lockout

threshold (6.7 V typ), and a power-on reset that sets all the I²C registers to zero when the

1.3

I²C interface and diagnostic

The main functions of the device are controlled via the I²C bus by writing 5 bits on the

system register (SR bits in write mode). In the same register there are 5 bits that can be

read back (SR bits in read mode) and provide 2 diagnostic functions, whereas the other 3

bits are for internal usage (TEST1, TEST2, and TEST3).

Two bits report the diagnostic status of the two internal monitoring functions:

–

OTF: over temperature flag. If an overheating occurs (junction temperature

exceeds 150 °C), the OTF I²C bit is set to “1”.

–

OLF: overload flag. If the output current required exceeds the current limit

threshold or a short circuit occurs, the OLF I²C bit is set to “1”.

Moreover, three bits report the last output voltage register status (EN, VSEL, LLC) received

by the I²C. The LNBH23L I²C interface address can be selected from two different

addresses by setting the voltage level of the dedicated ADDR pin according to Table 1:

1.3.1

Reserved I²C address

The device has another I²C address reserved only for internal usage, see Table 2.

Table 1.

LNBH23L I²C addresses

Pin Set-up

Write (HEX)

Read (HEX)

ADDR=Low or floating

0x14

0x15

ADDR=High

0x16

0x17

Table 2.

LNBH23L other I²C addresses

Pin Set-up

Write (HEX)

Read (HEX)

ADDR=Low/High or floating

0x10

0x11