Datasheet

R01DS0098EJ0180 Rev.1.80 Page 189 of 208
May 13, 2014
RX63N Group, RX631 Group 5. Electrical Characteristics
5.10 Battery Backup Function Characteristics
Note: The VCC-off period for starting power supply switching indicates the period in which VCC is below the minimum value of the
voltage level for switching to battery backup (V
DETBATT
).
Figure 5.68 Battery Backup Function Characteristics
Table 5.35 Battery Backup Function Characteristics
Conditions: VCC = AVCC0 = VREFH = VCC_USB = 2.7 to 3.6 V, VREFH0 = 2.7 V to AVCC0, V
BATT
= 2.0 to 3.6 V (for products
with 100 pins or more), V
BATT
= 2.3 to 3.6 V (for the 64-pin product)
VSS = AVSS0 = VREFL/VREFL0 = VSS_USB = 0 V
T
a
= T
opr
Item Symbol Min. Typ. Max. Unit
Test
Conditions
Voltage level for switching to battery backup V
DETBATT
2.50 2.60 2.70 V Figure 5.68
Lower-limit V
BATT
voltage for power supply switching due to
VCC voltage drop
V
BATTSW
2.70 — —
VCC-off period for starting power supply switching t
VOFFBATT
200 — — μs
VBATT
VCC
V
DETBATT
V
BATTSW
t
VOFFBATT
VBATT
Switching prohibited VBATT
Switching prohibited
VCC
Return from battery
backup not possible
VCC supply
VCC supplyVBATT supply
VCC voltage
guaranteed range
VBATT voltage
guaranteed range
Backup power
area
When VCC falls below V
DETBATT
, the voltage for switching to battery backup, make sure that VCC does not rise
above V
DETBATT
during the VCC-off period required to start switching between power supplies.
The VBATT voltage when the supplied power source switches from Vcc to V
BATT
should not be lower than V
BATTSW
,
the lower-limit VBATT voltage for switching between power supplies due to a drop in the VCC voltage.
Note.