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MANUAL
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7/198 17-LXE 108 566 Uen
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2.3.3.2 VREF
VREF is a module supply voltage reference output from the module to be used, current amplified, by the application
for its interface circuitry. The signal is applied to the system interface when the module is powered up.
The signal can also be used as an application wakeup signal if the Alarm function of the RTC is used.
Limits
Parameter
Symbol
Condition
Minimum
Nominal
Maximum
Units
Supply voltage
reference
VREF 2.5
2.75
3.0
V
Voltage
level
VREF
Alarm
indication
0.8 2.0
Output impedance
R
OUT
Short circuit
protection
0.9 1 1.1 k
Ω
Module output
current
I
L
2.75
6.0
μ
A
Application load
R
L
Resistance to
GND
470 1000
k
Ω
rise time
t
r
10
us
fall time
t
f
100
ms
Table 8: VREF Electrical Parameters
Vref Voltage level vs. temp
2.45
2.50
2.55
2.60
2.65
2.70
2.75
2.80
-40
-30
-20
-10
0
10
20
30
40
50
60
70
80
Temperature (deg C)
V
o
lt
age l
evel
(
V
)
Vref 1M load
Vref 100k load
Figure 7: VREF vs. temperature
