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Iridium 9523/9523N L-Band Tra nsce iver Integrator Devel opme nt Guide
Revis ion 7 .4
3.2.2
Power On/Off Control, TRX_ON
The input signal TRX_ON is provided to allow the Iridium Core 9523/9523N to be powered off. This signal
controls the power regulators on the Iridium Core 9523/9523N.
The Iridium Core 9523/9523N starts up when power is applied and the TRX_ON input is high. As long as the
input voltage is applied, logic high on this line turns the Iridium Core 9523/9523N on and a logic low turns it
off. If this line is not required then it must be connected directly to the VBAT supply.
Prior to turning off the modem, command AT*P0 should be issued to ensure all memory write activity is
completed.
When the Iridium Core 9523/9523N is powered off, the power-on-reset circuit requires 2 seconds for voltages
to decay. Product Developers should therefore not reapply power until this time has elapsed after power has
reached 0V. If the 2 second wait time is not adhered to, the reset circuit may not operate and the modem
could be placed in a non-operational state. The state is not permanent and can be rectified by the above
procedure.
Damage may be caused if TRX_ON is high and VBAT is not supplied. Partners must ensure tha t this condition
cannot occur either by generating TRX_ON from VBAT or by adding protection circuitry such as a clamp diode
between TRX_ON and VBAT.
3.2.3
Typical Power Usage Profile
The amount of current taken by the Iridium Core 9523/9523N on its two supply rails depends on whether it is
active in a call and the 'power step' level that the transmitter is using. The current consumption during a call
at the highest power step is shown in Figure 8.
I/mA
1000
900
800
700
600
500
400
300
200
100
10
Proprietary & Confidential Information
Distribution of guide restricted to product dev elopers only . Inf ormation contained in this guide is subject to change without notice.
.
Figure 8: Current Profile of Supply Rails
Current in VBOOST Rail
Current in VBAT Rail
20
30
40
50
60
70
t/ms
80
90
100
27
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