Application Note
[Page 7]
Design Considerations of EMW3239
Figure 2.3 SMT Package
DC Power Design
2.3
Peak current of the module is approximately 360mA. DC/DC with maximum output current 600mA is
suggested as power supply. DC/DC is better than LDO in low power consumption.
Route should be particularly aware for DC/DC power supply. Compact element, excellent connection
between input and output ground, long distance between feedback signal and inductance and Schottky diode are
required for route. Details about the requirements should refer to the datasheet of DC/DC device.
Maximum output current and dissipate heat should be aware for the using of LDO. voltage drop is 1.7V when
voltage reduce from 5V to 3.3V. If the current is 300mA, power consumption is1.7V * 360mA=612mW,
PowerDisspation is a parameter on LDO datasheet which should be over 510mW (same methods are used to
calculate other input voltage).
The problem rate about final product would be reduced by fully consideration of power design.
Pin Function
2.4
Set module in different mode by combo PIN 36
（
BOOT
）
, PIN37
（
STATUS
）
, PIN9(ELINK).
Table 2.1 Switch Mode
BOOT
STATUS
ELINK
FUNCTION
H
/
/
NORMAL WORK
L
H
L
ATE
L
L
H
QC
L
H
H
BOOTLOADER
