Technical data

SYSTEM CONNECTOR INTERFACE
29
LZT 123 8020 R1A
Hard Shutdown Sequence
ON/OFF
VIO
t
HSD
t
PULSE
Figure 5.4 Hard Shutdown Sequence
Symbol Parameters Conditions Min. Typ Max Unit
t
HSD
Time to complete
hardware shutdown
2 - 11 s
t
PULSE
(4)
Application
ON/OFF pulse
width
ON/OFF low
until VIO is
disabled
t
HSD
10 - s
(4) To implement the Hard Shutdown of the GM47r5, the ON/OFF pulse must be
held low until the sequence is complete. Ensure that ON/OFF is not released
before VIO has been deactivated by the module.
A hard shut down is only necessary where a normal power down has failed,
this should only happen if the software has 'greyed out'. This has never been
seen in the modules but is a safety mechanism build into the chipset where
the power will be cut from the chips enabling the unit to be powered up
normally.
5.6.1 VIO - 2.75V Supply
VIO provides an output voltage derived from an internal 2.75V
regulator. Its electrical characteristics are shown below.
Parameter Min. Typ. Max. Units
Output Voltage (I
load
= 50 mA) 2.70 2.75 2.85 V
Load current 75 mA
You can use this output for the following:
• to indicate that the radio device is powered;
• to power interface circuits, external to the radio device.