MP2214 – 16V, 4A, 600kHz SYNCHRONOUS STEP-DOWN CONVERTER
Selecting the Inductor
VCC Power Supply
A 1µH to 4.7µH inductor with DC current rating at
least 25% higher than the maximum load current
is recommended for most applications. For best
efficiency, the inductor DC resistance shall be
<10mꢀ. See Table 2 for recommended inductors
and manufacturers. For most designs, the
inductance value can be derived from the
following equation:
VCC is the power supply of both the internal control
circuit and the gate drivers.
Generally, the VCC power supply could be provided
directly by a proper power rail or generated from
other VCC generation circuits. For instance, Figure4
shows a typical VCC generation circuit for VOUT=5V
application.
It is noteworthy that the voltage applied on the VCC
pin should never be higher than 6V.
VOUTx(V − VOUT
)
IN
L =
V xΔILxfOSC
IN
APPLICATION INFORMATION
where ∆IL is Inductor Ripple Current. Choose
inductor ripple current approximately 30% of the
maximum load current, 4A. The maximum
inductor peak current is:
Setting the Output Voltage
The external resistor divider sets the output
voltage (see Figure1). For typical applications,
choose R2 to be 10kꢀ, R1 is then given by:
ΔIL
2
IL(MAX) = ILOAD
+
VOUT
R1 = R2(
−1)
0.8V
Under light load conditions, larger inductance is
recommended for improved efficiency
Table 1—Resistor Selection vs. Output
Voltage Setting
Input Capacitor Selection
L (μH)
COUT
(ceramic)
VOUT (V) R1 (kΩ) R2 (kΩ)
The input capacitor reduces the surge current
drawn from the input and switching noise from
the device. The input capacitor impedance at the
switching frequency shall be less than input
source impedance to prevent high frequency
switching current passing to the input. Ceramic
capacitors with X5R or X7R dielectrics are highly
recommended because of their low ESR and
small temperature coefficients. For most
applications, a 47µF capacitor is sufficient.
1.2
1.5
1.8
2.5
3.3
5
10
10
10
10
10
1μH-4.7μH
1μH-4.7μH
1μH-4.7μH
1μH-4.7μH
1μH-4.7μH
47μF
8.75
12.5
21.25
31.25
47μF
47μF
47μF
47μF
Table 2—Suggested Surface Mount Inductors
Max
DCR
(mꢀ)
Current
Rating
(A)
Inductance
Dimensions
L x W x H (mm3)
Manufacturer
Part Number
(μH)
TOKO
FDA1055-3R3M
744314330
3.3
3.3
3.3
7.3
9.6
11.7
8
10.8x11.6x5.5
7x6.9x5
Wurth Electronics
TDK
ULF100457-3R3N6R9
11.6
7.5
10x9.7x4.5
MP2214 Rev. 0.9
9/1/2010
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