S50 Hardware User Guide
1VV0301505 Rev. 1
Page
13
of
53
2018-03-02
4.
APPLICATION INTERFACE
Power Supply
S50 require a power supply with the following characteristics:
Typical: 3,0V
DC
, min.: 1,7V
DC
, max.: 3,6V
DC
, thereby delivering > 25 mA peak
S50 is designed to be powered from 3V coin cell batteries e.g. CR2032 directly,
or any other power source complying with the given requirements. For optimal performance,
a stable supply is recommended. Furthermore, it is recommended to place a capacitor in
parallel to the CR2032 3V coin cell battery in order to prolong battery lifetime, by
compensating the effects of the rising source resistance of the battery to pulsed loads. Since
the isolation resistance of this capacitor will discharge the battery in a not insignificant scale,
the capacitor should be chosen under consideration of the following rules:
•
capacitance as small as necessary
•
nominal voltage as high as possible
•
case size as large as possible
•
use X7R instead of X5R
.
S50
XC6209F-3.3
E-6,F-6
VSUP
GND:
A-7,E-7,F-7,B-[5:8],
C-[5:8],D-8,E-8,F-8
1µ + 100n
1µ
VOUT
VSS
VIN
CE
5
1
3
2
+5VDC
Figure 3: S50 Example Power Supply with LDO
It is strongly recommended NOT to switch the module power
supply on/off while other parts of the circuitry stay powered. This
mostly leads to hardly controllable back-feeding issues.
Due to the ultra-low power design a few µAmps are enough to raise
VSUP to an undefined state, which may cause a hang-up deadlock if
power is switched on again.
Any I/O pin at a voltage > 0,3V while the supply VSUP is at 0V
violates the abs. max. ratings given in chapter 5.1 Absolute Maximum
Ratings.
It is instead recommended to use the advanced power management
features, which may reduce the supply current to 300nA.
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