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PDF MP1474 Data sheet ( Hoja de datos )
| Número de pieza | MP1474 | |
| Descripción | High-Efficiency 2A 16V 500kHz Synchronous Step-Down Converter | |
| Fabricantes | MPS | |
| Logotipo |  |
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MP1474
The Future of Analog IC Technology
DESCRIPTION
The MP1474 is a high-f requency, synchronous,
rectified, st ep-down, switch-mode converter
with built-in power MOSFETs. It o ffers a very
compact solution to achieve a 2A continuous
output curr ent with e xcellent loa d and line
regulation o ver a wide input supply range. The
MP1474 ha s synchronous mode operation fo r
higher efficiency over t he output current load
range.
Current-mode operation provides fast transien t
response and eases loop stabilization.
Full protection feature s include over-current
protection and thermal shut down.
The MP147 4 requires a minimal number of
readily-available standard external components,
and is available in a space- saving 8-pin
TSOT23 package.
High-Efficiency, 2A, 16V, 500kHz
Synchronous, Step-Down Converter
FEATURES
Wide 4.5V-to-16V Operating Input Range
100m Ω/40mΩ Low RDS(ON) Internal Power
MOSFETs
High-Efficiency Synchronous Mode
Operation
Fixed 500kHz Switching Frequency
Synchronizes from a 200kHz-to-2MHz
External Clock
Power-Save Mode at Light Load
Internal Soft-Start
Power Good Indicator
OCP Protection and Hiccup
Thermal Shutdown
Output Adjustable from 0.8V
Available in an 8-pin TSOT-23 Package
APPLICATIONS
Notebook Systems and I/O Power
Digital Set-Top Boxes
Flat-Panel Television and Monitors
Distributed Power Systems
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Quality Assurance. “MPS” and “The
Future of Analog IC Technology” are Registered Trademarks of Monolithic
Power Systems, Inc.
TYPICAL APPLICATION
4.5V-16V
VIN
C1
22
EN/
SYNC
C5 R5
0.1 100k
2 IN
5
R3
20
BST
MP1474
6 EN/SYNC
SW 3
C4
L1
7 VCC
1 PG
GND
4
FB 8
R6
16k
3.3V/2A
C2
47 R1
40.2k
R2
13k
Efficiency vs.
Output Current
100VOUT=3.3V, IOUT=0.01A-2A
95
90 VIN=5V
85 VIN=12V
80
75 VIN=16V
70
65
60
55
50
0.0 0.4 0.8 1.2 1.6
OUTPUT CURRENT (A)
2.0
MP1474 Rev. 1.0
9/26/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
1
http://www.Datasheet4U.com
1 page  
MP1474 – SYNCHRONOUS STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
Performance waveforms are tested on the evaluation board of the Design Example section.
VIN = 12V, VOUT = 3.3V, L=5.5μH, TA = 25°C, unless otherwise noted.
100
95
90
85
80
75
70
65
60
55
50
0.0
VIN=5V
VIN=12V
VIN=16V
0.4 0.8 1.2 1.6
OUTPUT CURRENT (A)
2.0
100
95
90
85
80
75
70
65
60
55
50
0.0
VIN=5V
VIN=12V
VIN=16V
0.4 0.8 1.2 1.6
OUTPUT CURRENT (A)
2.0
100
95
90
85
80
75
70
65
60
55
500.0
VIN=5V
VIN=12V
VIN=16V
0.4 0.8 1.2 1.6 2.0
OUTPUT CURRENT (A)
100
95
90
85
80
75
70
65
60
55
50
0.0
VIN=5V
VIN=12V
VIN=16V
0.4 0.8 1.2 1.6 2.0
OUTPUT CURRENT (A)
100
95
90
85
80
75
70
65
60
55
50
0.0
VIN=7V
VIN=12V
VIN=16V
0.4 0.8 1.2 1.6
OUTPUT CURRENT (A)
2.0
Case Temperature Rise
vs. Output Current
IOUT=0A-2A
18
15
12
9
6
3
0
0 0.5 1 1.5
OUTPUT CURRENT (A)
2
Short Entry
IOUT=0A
VOUT
2V/div.
VPG
5V/div.
VIN
10V/div.
VSW
10V/div.
IINDUCTOR
5A/div.
Short Recovery
IOUT=0A
VOUT
2V/div.
VPG
5V/div.
VIN
10V/div.
VSW
10V/div.
IINDUCTOR
5A/div.
Startup through Enable
IOUT=0A
VOUT
2V/div.
VPG
5V/div.
VEN
5V/div.
VSW
10V/div.
IINDUCTOR
2A/div.
MP1474 Rev. 1.0
9/26/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
5
5 Page 
MP1474 – SYNCHRONOUS STEP-DOWN CONVERTER
APPLICATION INFORMATION
Setting the Output Voltage
The external resistor divider sets the output
voltage (see Typical Application on page 1). The
feedback resistor R1 also sets the feedback loop
bandwidth with the internal compensation
capacitor (see Typical Application on page 1).
Choose R1 around 40kΩ. R2 is then given by:
R1
R2
V
1OUT
0.807 V
The T-type network—as shown in Figure 5—is
highly recommended when VOUT is low.
Cf
8
FB
Rt
R1
R2
VOUT
Figure 5: T-Type Network
Table 1 lists the re commended T -type resist ors
value for common output voltages.
Table 1: Resistor Selection for Common Output
Voltages
VOUT
(V)
R1 (kΩ) R 2 (kΩ) R t (kΩ) C f(pF) L(μH)
1.0 20.5
84.5
82 15 2.2
1.2 30.1
61.9
82 15 2.2
1.8 40.2
32.4
33 15 4.7
2.5 40.2
19.1
33 15 4.7
3.3 40.2
13 16 15 5.5
5 40.2
7.68 16
15 5.5
Selecting the Inductor
Use a1µH-t o-10µH inductor with a DC current
rating of at least 25% percent higher than the
maximum load current for most applications. For
highest efficiency, use an inductor with a DC
resistance less than 15mΩ. For most designs,
the inductance value can be derived from the
following equation.
L1
VOUT (VIN VOUT )
VIIN L fOSC
Where ΔIL is the inductor ripple current.
Choose th e inductor ripple current to b e
approximately 30% of th e maximum load current.
The maximum inductor peak current is:
IL(MAX)
ILOAD
IL
2
Use a larg er inductor for improved efficiency
under light-load conditions—below 100mA.
Selecting the Input Capacitor
The input current to the step-down converter is
discontinuous, therefore requires a capacitor is to
supply the AC current to the step-down converte r
while maintaining the DC input volt age. Use lo w
ESR capacitors for the best performance. Use
ceramic ca pacitors wit h X 5R or X7R dielectrics
for best results because of their low ESR an d
small temperature coefficient s. For most
applications, use a 22µF capacitor.
Since C1 a bsorbs the input switching current, it
requires an adequate ripple curren t rating. The
RMS curre nt in the input capacitor can b e
estimated by:
IC1 ILOAD
VOUT
VIN
1
VOUT
VIN
The worse case condition occurs a t VIN = 2V OUT,
where:
IC1
ILOAD
2
For simplification, choose an input capacitor wit h
an RMS current rating greater tha n half of th e
maximum load current.
The input capacitor can be electrolytic, tantalum
or ceramic. When using electrolytic or tantalum
capacitors, add a small, high qu ality ceramic
capacitor (e .g. 0.1 μF) p laced as clo se to the IC
as possib le. When using ceramic capacitor s,
make sure t hat they have enough capacitance to
provide suff icient charge to prevent excessiv e
voltage ripple at input. The input voltage ripple
caused by capacitance can be estimated as:
VIN
ILOAD
fSC
1
VOUT
VIN
1
VOUT
VIN
MP1474 Rev. 1.0
9/26/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet MP1474.PDF ] | |
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