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Backup Mode
The backup mode is established by setting all inputs Low except for B.U. (Vbat: 2.6 to 3.0V). In this mode, the
low power consumption can be achieved by stopping all oscillators except for RTC oscillator. Although all
registers are initialized, the SRAM for both of Ephemeris data and Almanac data in backup area are held.
Antenna Sense (Option)
The antenna sensing function detects three kinds of external active antenna connection conditions, open/
normal/short, by using A/D converter incorporated into the CXD2951.
The @ANT command shows the previous antenna sensing result and users would know the three kinds of
conditions. For details, see the CXD2951 Communication Command Specifications.
T + 1
RTC
Antenna
condition
V
DD
Voltage
(RFIN)
0
Threshold Levels
The threshold current Ir is as follows when V
open:
normal: 3.7mA ≤ Ir ≤ 44.0mA
short:
44.0mA < Ir
T + 2
T + 3
T + 4
T + 5
T + 6
open
Approx.1s
Antenna status detection timing
Ir < 3.6mA
T + 7
T + 8
T + 9 T + 10 T + 11 T + 12 T + 13 T + 14 T + 15 T + 16 T + 17
normal
short
Approx. 3s
= 3.3V.
DD
- 11 -
GXB5005
(Second)
normal
Approx. 3s
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