CDMA and GSM / UMTS Mini Card Hardware Integration Guide
26
Proprietary and Confidential
2130114
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
μ
s
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
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
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
5),
this
current
draw
could
increase
from
2.4
A
to
2.75
A,
as
shown
in
Enum eration
3.3V
W _D isable#
U SB D +
Startup tim e
