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PDF ELM613DA Data sheet ( Hoja de datos )
| Número de pieza | ELM613DA | |
| Descripción | synchronous step-down DC/DC converter | |
| Fabricantes | ELM Technology | |
| Logotipo |  |
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ELM613DA 2A, 20V, 550kHz, synchronous step-down DC/DC converter
■General description
ELM613DA is 550KHz fixed frequency PWM synchronous step-down regulator. ELM613DA is operated from
4.75V to 20V, the generated output is adjustable from 0.923V to 18V, and the output current can be up to 2A.
The integrated two MOSFET switches is with turn on resistance of 0.085Ω. Current mode control provides fast
transient response and cycle-by-cycle over current protection. The shutdown current is 1μA typical. Adjustable
soft start prevents inrush current at turn on. ELM613DA is with thermal shutdown.
■Features
• Programmable soft start
• Short circuit protection
• Thermal shutdown protection
• Input voltage
: 4.75V to 20V
• Output voltage
: 0.923V to 18V
• Output current
: 2A
• High efficiency
: Max.93%
• Power MOSFET switches : 85mΩ
• Shutdown current
: Typ.1µA
• Fixed frequency
: Typ.550kHz
• Package
: SOP-8
■Application
• Distributed power system
• Network system
• FPGA, DSP, ASIC power supply
• Notebook computer
• Green electronics and appliance
■Maximum absolute ratings
Parameter
Symbol
Limit
VIN power supply voltage
Vin -0.3 to +21
Apply voltage to SW
Vsw -0.3 to Vin+0.3
Apply voltage to BS
Vbs Vsw-0.3 to Vsw+6
Apply voltage to FB
Vfb -0.3 to +6
Apply voltage to COMP
Vcomp
-0.3 to +6
Apply voltage to EN
Ven -0.3 to +6
Apply voltage to SS
Vss -0.3 to +6
Power dissipation
Pd 630
Operating temperature range
Top
-40 to +85
Storage temperature range
Tstg -65 to +150
Caution:Permanent damage to the device may occur when ratings above maximum absolute ones are used.
Unit
V
V
V
V
V
V
V
mW
°C
°C
■Selection guide
ELM613DA-N
Symbol
a
Package
b Product version
c Taping direction
* Taping direction is one way.
D: SOP-8
A
N: Refer to PKG file
ELM613DA - N
↑↑ ↑
ab c
11 - 1
Rev.1.3
1 page  
ELM613DA 2A, 20V, 550kHz, synchronous step-down DC/DC converter
Where Vfb is the feedback voltage and Vout is the output voltage. Thus the output voltage is:
Vout = 0.923 × (R1 + R2) / R2
R2 can be as high as 100kΩ, but a typical value is 10kΩ. Using the typical value for R2, R1 is determined by:
R1 = 10.83 × (Vout − 0.923) (kΩ)
3. Inductor
The inductor is required to supply constant current to the output load while being driven by the switched input
voltage. A larger value inductor will result in less ripple current that will result in lower output ripple voltage.
However, the larger value inductor will have a larger physical size, higher series resistance, and/or lower satura-
tion current. A good rule for determining the inductance to use is to allow the peak-to-peak ripple current in the
inductor to be approximately 30% of the maximum switch current limit. Also, make sure that the peak inductor
current is below the maximum switch current limit. The inductance value can be calculated by:
L = [ Vout / (fs × ΔIl) ] × (1 − Vout/Vin)
Where Vout is the output voltage, Vin is the input voltage, fs is the switching frequency, and ΔIl is the peak-to-
peak inductor ripple current.
Choose an inductor that will not saturate under the maximum inductor peak current. The peak inductor current
can be calculated by:
Ilp = Iload + [ Vout / (2 × fs × L) ] × (1 − Vout/Vin)
Where Iload is the load current.
The choice of which style inductor to use mainly depends on the price vs. size requirements and any EMI re-
quirements.
4. Optional Schottky diode
During the transition between high-side switch and low-side switch, the body diode of the low-side power
MOSFET conducts the inductor current. The forward voltage of this body diode is high. An optional Schottky
diode may be paralleled between the SW pin and GND pin to improve overall efficiency. Table 1 lists example
Schottky diodes and their Manufacturers.
Part number Voltage and current rating
Vendor
B130
30V, 1A
Diodes Inc.
SK13
30V, 1A
Diodes Inc.
MBRS130
30V, 1A
International Rectifier
Table 1: Diode selection guide.
5. Input capacitor
The input current to the step-down converter is discontinuous, therefore a capacitor is required to supply the
AC current to the step-down converter while maintaining the DC input voltage. Use low ESR capacitors for the
best performance. Ceramic capacitors are preferred, but tantalum or low-ESR electrolytic capacitors may also
suffice. Choose X5R or X7R dielectrics when using ceramic capacitors. Since the input capacitor (Cin) absorbs
the input switching current it requires an adequate ripple current rating. The RMS current in the input capacitor
can be estimated by:
Icin = Iload × [ (Vout/Vin) × (1 − Vout/Vin) ]1/2
The worst-case condition occurs at Vin = 2Vout, where Icin = Iload/2. For simplification, choose the input ca-
pacitor whose RMS current rating greater than half of the maximum load current.
11 - 5
Rev.1.3
5 Page 
ELM613DA 2A, 20V, 550kHz, synchronous step-down DC/DC converter
• Vout=5.0V : Cin=10µF, Cout=22µF, L=10µH, R1=30K R2=6.8K R3=15K
• V=5.0V C1=3.3nF, C2=0.1µF, C3=10nF, Top=25°C
Vout-Vin
6.0
5.5
5.0
4.5
4.0 Iout=10mA
3.5
3.0 Iout=100mA
2.5 Iout=1000mA
2.0
1.5
1.0
0.5
0 5 10 15 20
Vin (V)
EFFICIENCY-Iout
100
80
60 Vin=12V
40
20
00.1 1 10 100 1000 10000
Iout (mA)
5.5
5.4
5.3
5.2
5.1
5.0
4.9
4.8
4.7
4.6
4.50.1
Vout-Iout
Vin=12V
1 10 100 1000 10000
Iout (mA)
Vfb-Top
0.95
Vin=12V, Iout=100mA
0.94
0.93
0.92
0.91
0.90-40 -20 0 20 40 60 80
Top (°C)
Start Response
Vin=12V, No load
6
4
2
0
2
1
0
Time (4ms/div)
Load Transient Response
6.0 Vin=12V, Iout=1mA~1A
5.5
5.0
4.5
1.0
0.5
0
Time (100µs/div)
11 - 11
Rev.1.3
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet ELM613DA.PDF ] | |
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