LQH4C100K04 MPS [Monolithic Power Systems], LQH4C100K04 Datasheet - Page 9

• Manufacturer Part Number: LQH4C100K04
• Description: 1.6MHz Synchronous Step-Down plus 200mA LDO
• Manufacturer: MPS [Monolithic Power Systems]

APPLICATION INFORMATION
Output Voltage Setting
The external resistor divider sets the output
voltage. The feedback resistor R1 of the switcher
also sets the feedback loop bandwidth with the
internal compensation capacitor (see Figure 1).
R1 of the switcher should be 300kΩ for optimal
transient response. R2 is then given by:
R4 of the LDO should be 60kΩ for good loop
response. R3 is then given by:
Table 1—Resistor Selection vs. Output
Voltage Setting
MP2101 Rev. 1.0
8/18/2006
Manufacturer
Manufacturer
1.2V
1.5V
1.8V
2.5V
V
OUT
Coilcraft
Sumida
Sumida
Sumida
Sumida
Murata
Toko
Table 3—Inductors for Improved Efficiency at 25mA, 50mA, under 100mA Load.
300k
300k
300k
300k
(1%)
(1%)
(1%)
(1%)
TM
R1
R
3
Ω
Ω
Ω
Ω
R
=
DO1605T-103MX
2
LQH4C100K04
Part Number
Part Number
R
CDRH2D11
CDRH3D16
=
4
CR32-100
CR54-100
95.3k
300k
200k
150k
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
×
D521C
V
(1%)
(1%)
(1%)
(1%)
0
R2
(
OUT
6 .
V
0
R
V
Ω
Ω
Ω
OUT
Ω
6 .
1
1
Table 2—Suggested Surface Mount Inductors
V
−
2
1
−
120kΩ
190kΩ
60kΩ
90kΩ
MP2101 – 1.6MHz SYNCHRONOUS STEP-DOWN PLUS 200mA LDO
(1%)
(1%)
(1%)
(1%)
) 1
R3
Inductance (µH)
Inductance (µH)
© 2006 MPS. All Rights Reserved.
60kΩ
60kΩ
60kΩ
60kΩ
2.2
2.2
2.2
(1%)
(1%)
(1%)
(1%)
10
10
10
10
www.MonolithicPower.com
R4
Max DCR (Ω)
Max DCR (Ω)
Inductor Selection
A 1µH to 10µH inductor with a DC current rating
of at least 25% higher than the maximum load
current is recommended for most applications.
For best efficiency, the inductor DC resistance
should
recommended inductors and manufacturers.
For most designs, the inductance value can be
derived from the following equation:
Where ∆I
Choose the inductor ripple current to be
approximately 30% of the maximum load
current (800mA).
The maximum inductor peak current is:
Under light load conditions below 100mA, larger
inductance is recommended for improved
efficiency. Table 3 lists inductors recommended
for this purpose.
0.098
0.059
0.072
0.3
0.2
0.2
0.1
be
L
is inductor ripple current.
L
<200mΩ.
I
Current (A)
Current (A)
( L
=
Saturation
Saturation
MAX
V
OUT
1.27
1.63
1.20
V
1.0
1.2
1.0
1.2
)
IN
=
×
×
I
LOAD
(
∆
V
I
IN
L
See
×
−
+
f
OSC
V
∆
OUT
2
I
L
LxWxH (mm
Dimensions
3.2 x 3.2 x 1.2
Table
)
4 x 4 x 1.8
5 x 5 x 1.5
I
RMS
0.9
0.8
0.7
1.4
(A)
2
3
)
for
9