AN3352 datasheet(10/26 Pages) STMICROELECTRONICS

10 / 26 page

Block diagram and pin function description

AN3352

10/26

Doc ID 018526 Rev 3

12/29

TTX-A/

TTX-B

TTX enable

This pin, as well as the TTX I²C bit of the system register, is used to

control the TTX function enable before starting the 22 kHz tone

transmission. Set this pin floating or to GND if not used.

11/30

Reserved

To be connected to GND

9/32

PDC-A/

PDC-B

Pull-down control

To be connected to the external NPN transistor base to reduce the 22

kHz tone distortion in case of heavy capacitive load at light output

current. If not used it can be left floating.

13/28

EXTM-A/

EXTM-B

External modulation

External Modulation Input acts on VORX linear regulator output to

superimpose an external 22 kHz signal. Needs DC decoupling to the

AC source. If not used it can be left floating.

4/3

P-GND

Power ground

DC-DC converter power ground to be connected directly below the

ePad of the PCB top GND layer

ePad

On the bottom side of the QFN-32 package. It must be connected with

power ground and to the ground layer through vias to dissipate heat.

A-GND

Analog ground

Analog circuits ground

BYP

Bypass capacitor

Needed for internal pre-regulator filtering. The BYP pin is intended

only to connect an external ceramic capacitor. Any connection of this

pin to an external current or voltage sources may cause permanent

damage to the device.

8/1

ADDR-A/

ADDR-B

Address setting

Two I²C bus addresses available by setting the ADDR pin voltage level

15/26

ISEL-A/

ISEL-B

Current selection

The resistor RSEL connected between ISEL and GND defines the

linear regulator current limit threshold by the equation: Imax(typ.) =

10000 / RSEL

14/27

Reserved

To be left floating. Do not connect to GND.

Table 3.

LNBH24L pin description (continued)

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