Moteur de recherche de fiches techniques de composants électroniques |
|
ST72411R Fiches technique(PDF) 47 Page - STMicroelectronics |
|
ST72411R Fiches technique(HTML) 47 Page - STMicroelectronics |
47 / 71 page ST72411R 47/71 SMARTCARD SUPPLY SUPERVISOR (Cont’d) 5.5.4 Functional Description The core of the SSS is the internal reference volt- age generator that is used for the output voltage level regulation and for the Current Overload de- tection. Output regulation is achieved from the MCU VDD with a follower transistor used as output stage, as- sociated to a feedback regulation. Software control through the Status/Control regis- ter allows software to: s Turn-on / turn-off the SSS s Enable the overload detector s Enable interrupt in case of overload Smartcard Power Supply When disabled, the whole SSS is stopped in order to achieve minimum consumption. The SC_PWR line is tied to ground, and the I/O lines supplied by SC_PWR, are also tied to ground. When the SSS module is enabled, the SC_PWR line provides a regulated voltage to the smartcard, and the I/O lines have a logic “1” level identical to the smartcard supply ensuring a safe interface. Current Overload protection When a current overload occurs on the SC_PWR supply output, SC_PWR level drop is detected by the Current Overload detector when enabled. As a consequence, the SSS is turned-off with the SC_PWR line tied to ground and the SSSEN bit is cleared. On top of that, the OVLD flag is set into the Status/Control Register and an interrupt re- quest can be initiated. Note: The Current Overload detector must be en- abled by setting OVLDEN bit only after setting the SSSEN bit. Figure 37. Current Overload Detection Switching SC_PWR from 3V to 5V output and vice versa The usual (and safe) procedure is to test the card at 3V before selecting 5V output. The application should avoid making a direct tran- sition from 5V to 3V as a delay is required before the 3V level is reached (the delay depends on the external capacitor and card type). For a controlled transition from 5V to 3V it is rec- ommended to clear the SSSEN bit to tie the SC_PWR to ground before enabling 3V output. See Figure 52. Figure 38. Recommended transitions when switching the voltage regulator (SSSR bit). ISC_PWR 0mA 0V SHORT CIRCUIT VOVLD OVLDF FLAG VSC_PWR 0V VSC_PWR 3V 5V SSSR =0 SSSEN=1 SSSR=1 SSSEN=1 SSSR=1 SSSEN= 0 SSSR=0 SSSEN=1 t |
Numéro de pièce similaire - ST72411R |
|
Description similaire - ST72411R |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |