Rainbow Electronics AT86RF231 - Manual (Page 113)

113
8111A–AVR–05/08
AT86RF231
9.5 Battery Monitor (BATMON)
The main features of the battery monitor are:
• Configurable voltage threshold range: 1.7V to 3.675V
• Generates an interrupt when supply voltage drops below a threshold
9.5.1 Overview
The battery monitor (BATMON) detects and indicates a low supply voltage of the external supply
voltage at pin 28 (EVDD). This is done by comparing the voltage on the external supply pin 28
(EVDD) with a configurable internal threshold voltage. A simplified schematic of the BATMON
with the most important input and output signals is shown in
Figure 9-6 on page 113 .
Figure 9-6. Simplified Schematic of BATMON
9.5.2 Configuration
The BATMON can be configured using the register 0x11 (BATMON). Register subfield
BATMON_VTH sets the threshold voltage. It is configurable with a resolution of 75 mV in the
upper voltage range (BATMON_HR = 1) and with a resolution of 50 mV in the lower voltage
range (BATMON_HR = 0), for details refer to register 0x11 (BATMON).
9.5.3 Data Interpretation
The signal bit BATMON_OK of register 0x11 (BATMON) monitors the current value of the bat-
tery voltage:
• If BATMON_OK = 0, the battery voltage is lower than the threshold voltage
• If BATMON_OK = 1, the battery voltage is higher than the threshold voltage
After setting a new threshold, the value BATMON_OK should be read out to verify the current
supply voltage value.
Note, the battery monitor is inactive during P_ON and SLEEP states, see status register 0x01
(TRX_STATUS).
BATMON_HR
BATMON_VTH
4
EVDD
Threshold
Voltage
BATMON_OK
„1“
BATMON_IRQ
For input-to-output mapping
see control register
0x11 (BATMON)
DAC
+
-
D
Q
clear