Output - Fibocom NL668-LA Series Hardware Manual

Table 4-2 Filter capacitors design of power supply
Recommended Capacitor
220uF x 2
1uF, 100nF
39pF, 33pF
18pF, 8.2pF, 6.8pF
The power stability can ensure the normal operation of NL668-LA module. The power supply ripple limit
for the module is no more than 300mV (the circuit ESR < 100mΩ) requires special attention when design
circuit.
When the module is operating in GSM mode (Burst transmit), the maximum operating current can reach
3A, and the power voltage needs to be at least 3.3V. Otherwise, the module may power off or restart. The
power limit is shown in Figure 4-2:
VBAT
min:3.3V
4.3 1.8V Output
The NL668-LA series module outputs a 1.8V voltage through the VDD_EXT for the use of the internal
digital circuit of module. The voltage is the logic level of the module and can be used to indicate module
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FIBOCOM NL668-LA Series Hardware Guide
Application
Regulating capacitor
Digital signal noise
700, 850/900 MHz bands
1700/1800/1900,2100/2300,2500/
2600MHz bands
Burst transmit
Figure 4-2 Power limit
Description
Reduce power fluctuations during
module operation, requiring low ESR
Capacitor
LDO or DCDC power requires not
less than 440uF capacitor
Battery power can be properly
reduced to 100uF ~ 220uF capacitor
Filter clock and digital signal
interference
Filter low band RF interference
Filter middle/high band RF
interference
Burst transmit
Drop
VBAT≥3.3V
Ripple≤300mV
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