ACR3901U-S1 – Reference Manual
Version 1.09
www.acs.com.hk
Page 10 of 96
5.0. Hardware Design
5.1. Battery
ACR3901U-S1 is using a rechargeable Lithium-ion battery which has a capacity of 320 mAh.
5.1.1. Battery charging
Once the battery of ACR3901U-S1 runs out, it may be charged in any of the following modes: OFF,
USB, Bluetooth; as long as it is connected to a power outlet.
5.1.2. Battery life
The battery life is dependent on the usage of the device. Below is an estimate of the battery life
depending on the various work conditions:
Mode
Estimated Battery Life
Working Mode
24 days*
(1)
Standby Mode
28 days
(2)
OFF Mode
2 years
Table 2
: Estimated Battery Lifespan
*Note: Results may vary as it depends on the smart card used.
(1)
In Bluetooth mode, run 10 operations per day with 1 minute operation run.
(2)
In Bluetooth mode, set sleep time as 60 seconds and wake up once per day.
5.2. Bluetooth Interface
ACR3901U-S1 uses Bluetooth Low Energy (LE) 4.0 as the medium to pair the device with
computers/mobile devices.
5.3. USB Interface
The micro-USB port is used to connect the ACR3901U-S1 to the computer as battery charging port.
This port is also used in order for the ACR3901U-S1 to operate in PC-linked mode.
5.3.1. Communication Parameters
ACR3901U-S1 is connected to a computer through USB as specified in the USB Specification 2.0.
ACR3901U-S1 is working in full speed mode, i.e. 12 Mbps.
Pin
Signal
Function
1
V
BUS
+5 V power supply for the reader
2
D-
Differential signal transmits data between ACR3901U-S1 and computer
3
D+
Differential signal transmits data between ACR3901U-S1 and computer
4
GND
Reference voltage level for power supply
Table 3
: USB Interface Wiring
