Burst Transmission Current Requirements; Power Input (Vcc_3V6); Start-Up Current; Start-Up Current Peak Range - Sierra Wireless AirPrime SL808 Series Product Technical Specification & Customer Design Manuallines

Product Technical Specification & Customer Design Guidelines
26 Proprietary and Confidential - Specifications subject to change

3.1.1 Burst transmission current requirements

The power supply must be able to deliver high current peaks in a short time due
to the burst transmission nature of GSM. During these peaks, the ripple (U
the supply voltage must not exceed the level noted in
Table 3-3 describes radio burst rates in connected mode. For detailed power
consumption figures, see
Table 3-3: Radio burst rates — Connected mode
GSM / GPRS
a
Multislot class
Class 10
Class 12
a. (TBD) Table contents to be updated to classes supported by SL808X.

3.1.2 Power input (VCC_3V6)

An external power supply uses the VCC_3V6 pins to:
• Supply the AirPrime SL808X Embedded Module.
• Directly supply the RF components with 3.6 V.
· It is essential to keep a minimum voltage ripple at this connection in order
to avoid any phase error or spectrum modulation degradation.
· Insufficient power supply can significantly affect RF performance (TX
power, modulation spectrum, EMC performance, spurious emission,
frequency error, etc.).
• Provide reference voltage VREF_1V8 (through several internal regulators) for
the baseband signals. The host should draw less than 1 mA on this rail.
When the AirPrime SL808X Embedded Module is supplied with a battery, the total
impedance (battery + protections + PCB) should be such that the supply will be
>= 3.3 V during GSM burst mode operation (drawing a maximum peak current of
2.2 A for 577 µs (one slot) or 1154 µs (two slots) TX.

3.1.3 Start-up current

During the first second following Power ON, a current peak occurs. This current
peak (t ) has a duration of about 165 ms (typical).
Startup
Table 3-4 indicates the expected peak current range.
Table 3-4: Start-up current peak range
Current peak at
ambient
temperature (25°C)
t
Startup
Table 6-2 on page 77.
RF Power
Amplifier Burst duration
current
577
2.0 A peak
1154
VCC_3V6 VCC_3V6
min
(3.3 V)
150 mA
Table 3-1 on page 25.
Period
µs 4.615 ms
µs 4.615 ms
VCC_3V6
typ
(3.6 V) (4.3 V)
140 mA 115 mA
) on
ripp
Rising
time
10 µs
max
2400058