MB39A132QN-G-ERE1 Fujitsu Semiconductor America Inc, MB39A132QN-G-ERE1 Datasheet - Page 40

• Manufacturer Part Number: MB39A132QN-G-ERE1
• Description: IC CONV DC-DC LI-ION 32QFN
• Manufacturer: Fujitsu Semiconductor America Inc

Specifications of MB39A132QN-G-ERE1

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Operating Temperature: 25°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 32-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 865-1020

MB39A132
40
• Input capacitor selection
Select an input capacitor that has an ESR as small as possible. A ceramic capacitor is ideal. If a high-
capacitance capacitor is needed for which there is no suitable ceramic capacitor use a polymer capacitor or
a tantalum capacitor having a low ESR.
The ripple voltage by the switching operation of the DC/DC converter is generated in the power supply
voltage. Please consider the lower limit value of the input capacitor according to the allowable ripple voltage.
The ripple voltage of the power supply can be easily found by the following formula.
The ripple voltage of the power supply can be decreased by raising the switching frequency besides using
the capacitor.
The capacitor has its own frequency, temperature and bias voltage, therefore its effective capacitance can
be extremely small depending on the application conditions.
Select a capacitor whose rating has a sufficient margin against input voltage.
In addition, when using a capacitor having an allowable ripple current rating, select a capacitor that has a
sufficient margin against ripple current.
The allowable ripple current can be found by the following formula.
Δ
Irms ≥ I
ΔV
I
C
V
V
f
ESR : Series resistance element of input capacitance [Ω]
ΔIL : Inductor ripple current peak-to-peak value [A]
Irms : Allowable ripple current (Root-mean-square value) [A]
I
V
V
V
OMAX
OSC
OMAX
O
O
IN
IN
IN
IN
IN
=
: Switching power supply ripple voltage peak-to-peak value [V]
: Maximum charge current [A]
: Input capacitance [F]
: Switching power supply voltage [V]
: Charge voltage [V]
: Switching frequency [Hz]
: Maximum charge current [A]
: Switching power supply voltage [V]
: Charge voltage [V]
OMAX
I
OMAX
C
IN
×
×
√V
V
O
IN
× (V
V
× f
V
O
IN
OSC
IN
− V
+ ESR × (I
O
)
OMAX
+
ΔIL
2
)
DS04–27265–3E