SLM770A Module Hardware Design Manual
MeiG Smart Technology Co., Ltd 77/77
3.6.3 Reference Design for Power Supply
The design of the module power supply is very important because the performance of the module
depends largely on the power supply. The SLM770A must be supplied with at least 3A current capability.
If the voltage difference between the input voltage and the module supply voltage is not large, it is
recommended to use LDO as the power supply. If there is a large voltage difference between the input
and output voltages, it is recommended to use DCDC as the module power supply.
The figure below is the reference design of +5V power supply circuit. The design use Micrel LDO, model
MIC29302WU. Its typical output voltage is 3.8V and the peak load current reaches 3A.
Figure 5 Reference design for power supply input
3.6.4 VDD_EXT Voltage Output
When the SLM770A module is normally started, there is a voltage output on Pin7 with an output voltage
of 1.8V and a current load of 50mA. When the module is turned on, this power supply will always output,
the power supply capacity is limited, can’t be used for external heavy load circuit, can be used for the
level conversion chip reference voltage similar to light load applications.
Note: This pin is sensitive to ESD. If this pin is used, please advised to add an ESD component to
it for ESD prevention.
To prevent Flash data loss due to frequent module power outages, it is recommended that the customer
reserve three 47uF capacitors (0603 or 0805) externally on VDD_EXT, and determine whether to attach
capacitors based on actual conditions and scenarios.
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