SATELLINE-M3-R3
Integration Guide, Version 1.6
19
3.12
Time parameters for start-up and shutdown sequences
Parameter
Min time Recom. Time
(*
Explanation
T
vic
Input capacitor
charge time
0
>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.
T
ioms
Io module start
time
0
>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.
T
iovs
Io voltage startup
time
0
>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.
T
ior
IO drive fall time 0
>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 receiver module. This
way any latchup/brownout problems can be avoided.
T
iovf
IO voltage
discharge time
0
>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.
T
ldof
LDO discharge
time
0
>TBD
To avoid any possibility of reverse biasing of
regulators inside the module, 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 radio receiver module 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.
