UPSD3233 datasheet(138/170 Pages) STMICROELECTRONICS

138 / 170 page

uPSD3234A, uPSD3234BV, uPSD3233B, uPSD3233BV

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EMC CHARACTERISTICS

Susceptibility test are performed on a sample ba-

sis during product characterization.

Functional EMS (Electromagnetic

Susceptibility)

Based on a simple running application on the

product (toggling 2 LEDs through I/O ports), the

product is stressed by two electromagnetic events

until a failure occurs (indicated by the LEDs).

ESD. Electro-Static Discharge (positive and neg-

ative) is applied on all pins of the device until a

functional disturbance occurs. This test conforms

with the IEC 1000-4-2 Standard.

FTB. A burst of Fast Transient voltage (positive

and negative) is applied to VDD and VSS through a

100pF capacitor, until a functional disturbance oc-

curs. This test conforms with the IEC 1000-4-2

Standard.

A device reset allows normal operations to be re-

sumed. The test results are given in Table 109,

based on the EMS levels and classes defined in

Application Note AN1709.

Designing Hardened Software To Avoid Noise

Problems

EMC characterization and optimization are per-

formed at component level with a typical applica-

tion environment and simplified MCU software. It

should be noted that good EMC performance is

highly dependent on the user application and the

software in particular.

Therefore, it is recommended that the user applies

EMC software optimization and prequalification

tests in relation with the EMC level requested for

the user’s application.

Software Recommendations. The

software

flowchart must include the management of ‘run-

away’ conditions, such as:

–

Corrupted program counter

–

Unexpected reset

–

Critical data corruption (e.g., control registers)

Prequalification trials. Most of the common fail-

ures (unexpected reset and program counter cor-

ruption) can be reproduced by manually forcing a

low state on the RESET pin or the oscillator pins

for 1 second.

To complete these trials, ESD stress can be ap-

plied directly on the device over the range of spec-

ification values. When unexpected behavior is

detected, the software can be hardened to prevent

unrecoverable errors occurring (see Application

Note AN1015).

Absolute Maximum Ratings (Electrical

Sensitivity)

Based on three different tests (ESD, LU, and DLU)

and using specific measurement methods, the

product is stressed in order to determine its perfor-

mance in terms of electrical sensitivity. For more

details, refer to the Application Note AN1181.

Electro-Static Discharge (ESD). Electro-Static

discharges (a positive then a negative pulse sepa-

rated by 1 second) are applied to the pins of each

sample according to each pin combination. The

sample size depends on the number of supply pins

in the device (3 parts*(n+1) supply pin). The Hu-

man Body Model is simulated (see Table 110).

This test conforms to the JESD22-A114A Stan-

dard.

Table 109. EMS Test Results

Note: 1. Data based on characterization results, not tested in production.

Table 110. ESD Absolute Maximum Ratings

Note: 1. Data based on characterization results, not tested in production

Symbol

Parameter

Conditions

Level/

Class(1)

VFESD

Voltage limits to be applied on any I/O pin to

induce a functional disturbance

VDD = 4V; TA = 25°C; fOSC = 40MHz;

WDT off conforms to IEC 1000-4-2

Symbol

Parameter

Conditions

Maximum Value(1)

Unit

VESD(HBM)

Electro-static discharge voltage (Human

Body Model)

TA = 25°C

2000

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