xE922-3GR Hardware User Guide
1VV0301272
Rev.0.8 2017-01-05
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
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Page 42 of 112
Both V_BAT_PA and V_BAT are protected by Zener transient voltage suppressor diodes internal the module.
Although the internal transient suppressor also protects for reverse polarized input supply application, its max
power dissipation is limited as well.
For performance specification of this protection please consult the datasheet. (DF3A6.8FUT1 / ON
Semiconductor)
A low ESR buffer capacitor of adequate capacity must be provided on the application main board in order to
cut the current absorption peaks (either from system load or during cellular load TX slots , up to 2 A), taking
into account the sourcing power supply circuitry implementation is limited qua current rating and/or transient
response timing. The buffer capacitor must be selected in order to guarantee at all time V_BAT > BUV
battery under voltage (typical 3.0V).
For information, the total
‘
distributed
’
capacitance already present inside the module:
·
V_BAT_PA : 33uF
·
V_BAT : 82uF
5.2.
Output supply
5.2.1.
Linear voltage regulators
5.2.1.1.
VAUX_1P8V
parameter
symbol
value
unit
condition
Default
value
Default
state
Min
Typ
max
External
cappacitor
Cext
1000
1400
nF
Cappacitor
ESR
R_esr
100
ohm
100 Hz
0.05
ohm
1 MHz…30MHz
Output voltage Vreg
1.8
2.85
V
Configurable
1.8/2.5/2.8/2.85V
2.85V
OFF
Output
Current
Ireg
max
225
mA
Current
Limitation
Imax
400
mA
50% nominal
LDO voltage