L9779WD datasheet(31/170 Pages) STMICROELECTRONICS

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L9779WD

Functional description

169

6.3

VDD_IO function

6.3.1

Description of VDD_IO function and IC pin

The scope of the VDD_IO function and the new related VDD_IO pin is that the voltage level

of the L9779WD output ports can be adapted to the voltage levels of the ports of different

microcontrollers.The L9779WD output ports to be considered are the DO, CAN-RX,

K_RX,OUT_VRS, RST, WDA_INT. RST and WDA_INT are open drain structures.

The L9779WD input ports have a fixed voltage level which is compatible with both 3.3 V and

5 V µC-port voltages.

As the VDD_IO is an external supply, it is monitored and is evaluated for the reset

generation.

Concerning the max ratings, the VDD_IO pin should be specified similarly to the VDD5 pin

up to 19V.

The operating range would be at least from 2.9 V to 5.5 V.

The VDD_IO supply has a voltage monitoring similar to a VDD3V3 monitoring with min-

threshold 2.9 V and max-threshold 3.1V for low-voltage monitoring. Low-threshold is

adapted to VDD3 supply, even though both 3.3 V and 5 V supplies are possible. The

VDD_IO monitoring must be included in the RST logic to create a RST low output in case of

VDD_IO low voltage.

Table 8. VDD_IO electrical characteristics

Symbol

Parameter

Test condition

Min

Typ

Max

Unit

VDD_IO

IVDD_IO

Input current of VDD_IO

VB=14V,all VDD_IO

related pin without

load

VVDD_IO

Operation range

2.9

5.5

VVDD_IO

Maximum rating

-0.3

VVDD_IO_UV Under voltage threshold

2.9

3.0

3.1

tf_VDD_IO_UV Under voltage filter time

Tested by scan

µs

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