Satel SATELLINE-M3-R3 Guía de usuario descargar pdf (Pagina 20)

SATELLINE-M3-R3

User Guide, Version 1.2

3.11 Time parameters for start-up and shutdown sequences

Parameter

Min time

Recom. Time

Explanation

vic

Input capacitor

charge time

>50µs

When voltage is applied to VCC_IN the filter

capacitors inside the module are charged, creating a

small current surge. If the feeding power supply is not

very strong it is recommended to wait this time before

rising ENA_MODEM to minimize current surge.

ioms

Io module start

time

>50µs

ENA_MODEM rise enable the LDOs feeding the

FPGA and CPU inside the module. Waiting for the

internal parts of the module start before applying

external VCC_IO is good design practice to avoid

latchup problems.

iovs

Io voltage startup

time

>50µs

it is considered good design practice to KEEP all IO

signals (except ENA_MODEM) low or floating until

the internal parts of the module have power and the

IO voltage is stable.

ior

IO drive fall time

>10 µs

It is considered good design practice to set all IO

signals (except ENA_MODEM) low or floating before

starting to shut shutdown the modem. This way any

latchup/brownout problems can be avoided.

iovf

IO voltage

discharge time

>TBD

When using external IO voltage it is considered good

design practice to shut off this voltage and to let it

drop before shutting down the module.

ldof

LDO discharge

time

>TBD

To avoid any possibility of reverse biasing of

regulators inside the modem, it is considered good

design practice to use ENA_MODEM to shut down

the regulators before deactivating VCC_IN.

Table. Startup and shutdown sequence parameters.

*) Recommendations:

The modem is designed and tested for the minimum times mentioned in the table. The

recommendations are there for those who want to do the very best possible startup and startup

sequences.

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