M50 Hardware Design
M50_HD_V2.0
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VBAT
C2
C1
+
C3
C4
GND
100uF
100nF
10pF
0603
33pF
0603
Figure 4: Reference circuit for the VBAT input
3.3.3. Reference design for power supply
The power design for the module is very important, since the performance of power supply for the
module largely depends on the power source. The power supply is capable of providing the
sufficient current up to 2A at least. If the voltage drop between the input and output is not too high,
it is suggested to use a LDO as module’s power supply. If there is a big voltage difference
between the input source and the desired output (VBAT), a switcher power converter is prefer to
use as a power supply.
Figure 5 shows a reference design for +5V input power source. The designed output for the power
supply is 4.16V and the maximum load current is 3A. In addition, in order to get a stable output
voltage, a zener diode is placed close to the pins of VBAT. As to the zener diode, it is suggested to
use a zener diode which reverse zener voltage is 5.1V and dissipation power is more than 1 Watt.
DC_IN
C1
C2
MIC29302
U1
IN
OUT
EN
GND
ADJ
2
4
1
3
5
VBAT
100nF
C3
470uF
C4
100nF
R1
D1
120K
51K
R2
470uF
Figure 5
: Reference circuit for power supply
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