Timing Requirements; Power Ramp-Up; Power-Up Timing; Transmit Power Wave Form (Gsm) - Sierra Wireless MC5725 Hardware Integration Manual

CDMA and GSM / UMTS Mini Card Hardware Integration Guide
26
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.

Timing requirements

Power ramp-up

During the first 0.5 seconds, as the internal voltage regulators
are activated in sequence, several current transients of up to
500 mA with a 30 μs rise time may occur.
The supply voltage must remain within specified tolerances
while this is occurring.

Power-up timing

The unit is ready to enumerate with a USB host within a
maximum of 5.1 seconds (depending on module type) after
power‐up. (Most modules enumerate within 4 seconds.)
Note: The actual startup time may vary between the different module
types (for example, MC5725 versus MC8775).
Figure 2-6: Power-up timing diagram
3.3V
W _Disable#
USB D+
Startup tim e
Note: Startup time is the time after power-up when the modem is
ready to begin the enumeration sequence.
Transmit power wave form
(GSM)
As shown in Figure 2‐7, at maximum GSM transmit power, the
input current can remain at 2.4 A for up to 25% of each 4.6 ms
GSM cycle (1.15 ms). For Class 12 operation, the peak could
remain for 2.3 ms (four timeslots). The 2.4 A current draw is
for 50 ohm systems (1:1 VSWR). For worst‐case antenna
designs, such as 3.5:1 VSWR (as stated in Table 2‐5), this
current draw could increase from 2.4 A to 2.75 A, as shown in
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