User Guide

GM500-U1G_A

Hardware Development Guide

Table 2-4Power Supply

Pin Name Pin NO. Description Minimum Typical Maximum Unit

VBAT 50,51 Power supply for module 3.4 3.8 4.2 V

GND 3,9,11,20,21,31,36,46,49,5

2,61,63,78,80,81,87~102,1

07,117

Ground - -

GND signal is the power and signal ground of the module, which needs to be connected to the ground on the system board. If the

GND signal is not connected completely, the performance of module will be affected.

2.4.2. Decrease Voltage Drop

The power supply range of the module is 3.4V~ 4.2V. So we recommended to add Energy storage capacitor ( C6: 470μF). Filter

capacitor(10µF, 0.1µF, 33pF) need to be added to reduce interference. The capacitors should be placed close to the GM500-U1G_A’s

VBAT pins. The following figure shows structure of the power supply.

Figure 2–2 The input reference circuit of VBAT

In poor situation of the network, the antenna will transmit at the maximum power, so it’s recommended that continuous power

supply capacity is up to 2.5A when the module supports GSM mode, and it’s up to 1.5A in other modes.

The PCB traces from the VBAT pins to the power source must be wide enough to ensure that there isn’t too much voltage drop

occurs in the transmitting procedure. The width of VBAT trace should be no less than 2mm, and the principle of the VBAT trace is the

longer, the wider.

In addition, make the ground plane as complete as possible, and play more holes.

2.4.3. Reference Circuit of Power Supply



Option 1:DC-DC switching

The over-current capability requirement of DC/DC switching power supply needs to be above 2.5A. When the input and output

voltage difference is large, you need to select Buck circuit to improve translate efficiency.

The reference power supply circuit design with DC-DC is shown as figure below: