User's Manual

WM620 Hardware User Guide V1.1

2 Applicable interface

2.1 Power supply Interface

The Power supply part of the WM620 module contains:

Signal name

I/O

Function description

Note

22、23

VBAT

PWR

For power voltage input

VRTC

PWR

Coin cell backup voltage input

VDD_1.8V

PWR

Linear regulator 1.8V output

VDD_2.6V

PWR

Linear regulator 2.6V output

Characteristics of the VBAT are shown in the table 2-1.

Table 2-1, Input voltage characteristics

Status

Min. voltage

Typical voltage

Max. voltage

VBAT

+3.3 VDC

+3.8 VDC

+4.2VDC

NOTE：Make sure that the VBAT can never exceed 4.5VDC. Voltage higher than 4.5VDC may damage the

WM620 module.

2.1.1 Power Supply Requirements

VBAT is the main power input ranged from 3.3V to 4.2V DC, 3.8V DC is recommended. The average current

is less than 500mA@3.8VDC. But in the module’s transmitting mode, the largest current can burst up to 1.8A

providing the RF power amplifier. The burst current may cause deep voltage drop, and trigger the module into

a power reset. Thus a high value and low ESR capacitor must be installed on the VBAT, to avoid or reduce the

voltage drop caused by the RF power amplifier.

Figure 2-1a, current and voltage curve of VBAT