Texas Instruments 3138 155 232931 - Manual (Page 52)

CC2420
SWRS041B Page 52 of 89
In applications where the internal voltage
regulator is not used, connect VREG_EN
and VREG_IN to ground. VREG_OUT shall be left open. Note that the battery monitor
will not work when the voltage regulator is
not used.
VREG_IN
Internal
bandgap
voltage
reference
1.25 V
VREG_OUT
VREG_EN
Regulator
Enable / disable
Figure 28. Voltage regulator, simplified schematic
30 Battery Monitor
The on-chip battery monitor enables
monitoring the unregulated voltage on the
VREG_IN
pin. It gives status information
on the voltage being above or below a
programmable threshold. A simplified
schematic of the battery monitor is shown
in Figure 29.
VREG_IN
Internal
bandgap
voltage
reference
1.25 V
BATTMON.BATTMON_VOLTAGE[4:0]
BATTMON.BATTMON_OK
BATTMON.BATTMON_EN
Figure 29. Battery monitor, simplified schematic