Specifications

L506 Hardware Design

current

IVBAT(power-off)

Power supply

current

in power off

mode

IVBAT(power-save)

Power supply

current

in power save

mode(sleep

mode)

3.4.3 Power Supply Design Guide

Make sure that the input voltage at the VBAT pin will never drop below 3.4V even during a transmit

burst when the current consumption rises up to more than 2A. If the power voltage drops below 3.4V,

the RF performance of module may be affected. Using large tantalum capacitors (above 300uF) will be

the best way to reduce the voltage drops. If the power current cannot support up to 2A, users must

introduce larger capacitor (typical 1000uF) to storage electric power. For the consideration of RF

performance and system stability, some multi-layer ceramic chip (MLCC) capacitors (0.1/1uF) need to

be used for EMC because of their low ESR in high frequencies. Note that capacitors should be put

beside VBAT pins as close as possible. Also User should keep VBAT net wider than 2 mm to

minimize PCB trace impedance on circuit board. The following figure is the recommended circuit.

Figure 3-3 VBAT input application circuit

Note: The Cd, Ce, Cb, Cc and Cf are recommended being mounted for L506, but the Ca, Cb, Ce,

Ccand Cf for tune.

In addition, in order to get a stable power source, it is suggested to use a Zener diode of which reverse

Zener voltage is 5.1V and dissipation power is more than 500mW.

Table 3-8: Recommended Zener diode models