Specifications

Product Technical Specification & Customer Design Guidelines
26 Proprietary and Confidential - Specifications subject to change 2400058
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
ripp
) on
the supply voltage must not exceed the level noted in Tab l e 3- 1 on page 25.
Tabl e 3- 3 describes radio burst rates in connected mode. For detailed power
consumption figures, see Ta bl e 6 - 2 on page 77.
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
Startup
) has a duration of about 165 ms (typical).
Tabl e 3- 4 indicates the expected peak current range.
Table 3-3: Radio burst rates—Connected mode
GSM/GPRS
Multislot class
a
a. (TBD) Table contents to be updated to classes supported by SL808X.
RF Power
Amplifier
current
Burst duration Period
Rising
time
Class 10
2.0 A peak
577 µs 4.615 ms
10 µs
Class 12 1154 µs 4.615 ms
Table 3-4: Start-up current peak range
Current peak at
ambient
temperature (25°C)
VCC_3V6
min
(3.3 V)
VCC_3V6
typ
(3.6 V)
VCC_3V6
max
(4.3 V)
t
Startup
150 mA 140 mA 115 mA