User Guide

GM47/48 Design Guidelines
BA/SEM/MSC 02:0006 Rev PA1 12
C
BULK
ESR = 50mΩ
R
LINE
= 200mΩ
PSU LIMIT CBULK (min)
Transmit Burst
Vcc Dip (approx)
≥ 2.0 Amp 6000µF
200mV
1.5 Amp
6000µF
190mV
1.0 Amp 6000µF 190mV
0.5 Amp
*12000µF
200mV
Table 3.5
Note: When this capacitance is used with the PSU conditions stated,
the PSU will reach current limit. Although this condition on Vcc will
not adversely affect the module performance, this may not be a
condition appropriate to the supply and may adversely affect other
devices sharing the PSU output. If the PSU cannot be driven to current
limit, please select a non-current limiting configuration of CBULK and
RLINE. It is the responsibility of the application developer to ensure
correct operation of the PSU.
Further details of the GSM burst transmission waveform are given in
appendix III.
3.3.3 On/Off signal
The on/off line should be attached to an open collector drive or
momentary contact switch otherwise the module alarm clock feature
will not operate. The on/off line is wired Red internally with the alarm
wake up signal.