20-101-1221 Rabbit Semiconductor, 20-101-1221 Datasheet - Page 118

• Manufacturer Part Number: 20-101-1221
• Description: RCM4400W (JAPAN TELEC CERTIFIED)
• Manufacturer: Rabbit Semiconductor
• Series: RabbitCore®r

Specifications of 20-101-1221

• Frequency: 2.4GHz
• Modulation Or Protocol: 802.11 b
• Power - Output: 16dBm
• Voltage - Supply: 3.3V
• Current - Receiving: 450mA
• Current - Transmitting: 450mA
• Data Interface: Connector, 2 x 25 Header
• Memory Size: 512K Flash, 1MB SRAM
• Antenna Connector: SMA
• Operating Temperature: -20°C ~ 85°C
• Package / Case: Module
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Applications: -
• Sensitivity: -
• Data Rate - Maximum: -
• Other names: 316-1147

The drain on the battery by the RCM4400W is typically 7.5 µA when no other power is
supplied. If a 165 mA·h battery is used, the battery can last about 2.5 years:
The actual battery life in your application will depend on the current drawn by components
not on the RCM4400W and on the storage capacity of the battery. The RCM4400W does not
drain the battery while it is powered up normally.
Cycle the main power off/on after you install a backup battery for the first time, and when-
ever you replace the battery. This step will minimize the current drawn by the real-time
clock oscillator circuit from the backup battery should the RCM4400W experience a loss
of main power.
Rabbit’s Technical Note TN235, External 32.768 kHz Oscillator Circuits, provides addi-
tional information about the current draw by the real-time clock oscillator circuit.
C.1.2 Battery-Backup Circuit
Figure C-2 shows the battery-backup circuit.
The battery-backup circuit serves three purposes:
• It reduces the battery voltage to the SRAM and to the real-time clock, thereby limiting
• It ensures that current can flow only out of the battery to prevent charging the battery.
• A voltage, VOSC, is supplied to U13, which keeps the 32.768 kHz oscillator working
112
the current consumed by the real-time clock and lengthening the battery life.
when the voltage begins to drop.
NOTE: Remember to cycle the main power off/on any time the RCM4400W is removed
165 mA·h
----------------------- -
7.5 µA
from the Prototyping Board or motherboard since that is where the backup battery
would be located.
=
Figure C-2. RCM4400W Backup Battery Circuit
2.5 years.
W
W
RabbitCore RCM4400W