MP111 データシートの表示（PDF） - Monolithic Power Systems
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MP111 Datasheet PDF : 13 Pages
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MP111 – DYING GASP STORAGE AND RELEASE CONTROL IC
APPLICATION INFORMATION
SET STORAGE VOLTAGE
The storage voltage can be set by choosing
appropriate external feedback resistors R1 and
R2 which is shown in Figure 4.
Figure 4 – Feedback Circuit for Storage
Voltage
The storage voltage is determined by:
VSTORAGE
(1
R1
R2
)
VFB1
Here is the example, if the storage voltage is
set to be 20V, choose R2 to be 40kΩ, R1 will be
then given by:
R1
40k (20
VFB2
VFB2 )
760k
Table 1 lists the recommended resistors for
different storage voltages.
Table 1 – Resistor Selection for Different
Storage Voltages
VSTORAGE (V)
R1 (kΩ)
R2 (kΩ)
15
750
53.2
19
750
41.6
23
850
37.4
Select Release Voltage and Input Capacitors
The release voltage can be set by choosing
external feedback resistors R3 and R4 which is
shown in Figure 5.
Figure 5 – Release Feedback Circuit
Similarly, the release voltage is set by:
VRELEASE
(1
R3
R4
)
VFB2
However, the selection of R3 and R4 not only
determines the release voltage, but impacts the
stability. Generally, choosing R3 to be
300~500kΩ is recommended for a stable
performance with 47μF Cin. Table 2 lists the
recommended resistors setup for different
release voltages.
Table 2 – Resistor Selection for Different
Release Voltages
VRELEASE
(V)
R1
(kΩ)
R2
(kΩ)
Cf
Cin
(pF) (μF)
11
475
47.5
15
47
10.2
464
49.9
15
47
9.0
324
40.2
15
47
Select Storage Capacitor
The Storage Capacitor is for energy storage
during normal operation and the energy will be
released to VIN in case of losing input power.
Typically, a general purpose electrolytic
capacitor is recommended.
The voltage rating of storage capacitor needs to
be higher than the targeted storage voltage.
The voltage rating of storage capacitor can be
fully utilized since the voltage on storage
capacitor is very stable during normal operation.
There will be less ripple current/voltage for most
of the time during normal operation. The ripple
current rating of storage cap can be less
consideration.
The needed capacitance is dependent on how
long the dying gasp time based on typically
MP111 Rev. 1.0 1
www.MonolithicPower.com
10
4/25/2018
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