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PDF EML3173 Data sheet ( Hoja de datos )
| Número de pieza | EML3173 | |
| Descripción | Synchronous Step-Down DC-DC Converter | |
| Fabricantes | Elite Semiconductor | |
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ESMT
EML3173
3.0A, Synchronous Step-Down DC-DC Converter
General Description
EML3173 is a high efficiency, DC-DC synchronous
buck converter witch provides 3.0A output loading
after output voltage reach preset voltage. EML3173
uses different modulation algorithms for various
loading conditions. Under heavy load, EML3173
regulates the output voltage using Pulse Width
Modulation (PWM). The PWM mode provides low
output voltage ripple and fixed frequency noise.
While in light load, it enters Power Skip Modulation
(PSM) automatically to ensure a highly efficient
operation at light load condition. Under very heavy
load condition, or when the input voltage
approaches the output voltage, EML3173 enters low
dropout voltage operation under 100% duty cycle.
The internal generated 0.8V precision feedback
reference voltage is designed for low output voltage
request. Low Power-FET Ron synchronous switch
dramatically reduces conduction loss.
The EML3173 is available in an 8-pin, space-saving
E-SOP-8L package.
Typical Application
Features
Wide Operating Voltage Ranges : 2.6V to 5.5V
3.0A Output Current
High efficiency Buck Power Converter
Auto-select PSM/PWM (Mode=VCC)
Force PWM (Mode=GND)
Power Good Indicator
LDO mode: duty cycle: 100%
Synchronous Power Switches Rectification, no
Schottky Diode Required
1.4MHz Switching Frequency
Internal Soft-Start
Current Limit Protection
Over Temperature Protection
Output Shorting Protect
Output Over Voltage Protection
Applications
Cellular telephone
Wireless and DSL Modems
Digital Still Cameras
Portable Products
MP3 Players
Fig. 1 EML3173 application circuit
Elite Semiconductor Memory Technology Inc.
Publication Date: Dec. 2013
Revision: 0.1
1/18
1 page  
ESMT
EML3173
Typical Performance Characteristics
VIN=5.0V, TA=25℃, L=2.2uH, CIN=22uF*2, COUT=22uF*2, Mode=VCC, unless otherwise specified
Efficiency vs. Load (Fig. 3)
100
90
80
70
60
50
40
30
20
10
0
1
VI=3.6V
VI=5.0V
VI=4.2V
VO=3.3V
10 100 1000
Output Current (mA)
10000
Load Regulation (Fig. 5)
Efficiency vs. Load (Fig. 4)
100
VI=3.6V, PSM/PWM Operation
90
80
70
60
50
VI=4.2V
40
30
VI=3.6V, Forced PWM
VI=5.0V
20
10 V0=1.2V
0
1 10 100 1000 10000
Output Current (mA)
Load Regulation (Fig. 6)
3.36
3.34
3.32
3.30
3.28
3.26
3.24
1
VI=5.5V
VI=5.0V
10 100
Output Current (mA)
VO=3.3V
Mode=VCC
1000 10000
1.24
1.22
1.20
1.18
1.16
1.14
1
VI=5.5V
VI=5.0V
VO=1.2V
Mode=VCC
10 100 1000
Output Current (mA)
10000
Quiescent Current vs. Input Voltage (Fig. 7) Quiescent Current vs. Temperature (Fig. 8)
300
250
200
150 Quiescent Current
100
50 T=25℃
VFB=0.9V
Mode=VCC
0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
Input Voltage (V)
300
250
200
Quiescent Current
150
100
50 VI=5.0V
VFB=0.9V
Mode=VCC
0
-40 -20 0 20 40 60 80 100 120 140
Temperature (℃)
Elite Semiconductor Memory Technology Inc.
Publication Date: Dec. 2013
Revision: 0.1
5/18
5 Page 
ESMT
EML3173
Inductor
Value (µH)
2.2
2.2
Dimensions
(mm)
5.2 x 4.9 x 3.0 max.
4.9 x 4.9 x 4.1 typ.
Recommend Table
Component
Supplier
Model
CYNTEC
PCMB053T-2R2MS
TAIYO YUDEN
NRS5040T2R2NMGJ
ISAT
(A)
9
5
DCR
(mΩ)
29 typ.
28.6 typ.
Input Capacitor Selection
The input capacitor must be connected to the VIN pin and GND pin of EML3173 to maintain steady input
voltage and filter out the pulsing input current. The voltage rating of input capacitor must be greater than
maximum input voltage plus ripple voltage. In normal operation, the input current is discontinuous in a buck
converter. The source current waveform of the high-side MOSFET is a square wave. To prevent large voltage
transients, a low ESR input capacitor sized for the maximum RMS current must be used. The RMS value of input
capacitor current can be calculated by:
I RMS = I LOAD _ MAX *
VOUT
VIN
*
⎜⎜⎝⎛1
−
VOUT
VIN
⎟⎟⎠⎞
It can be seen that when VO is half of VIN, CIN is under the worst current stress. The worst current stress on CIN is
IO_MAX/3.0 A 47μF ceramic capacitor is recommended value in typical application.
Output Capacitor Selection
The output capacitor is required to maintain the DC output voltage. Low ESR capacitors are preferred to keep
the output voltage ripple low. In a buck converter circuit, output ripple voltage is determined by inductor value,
switching frequency, output capacitor value and ESR. The output ripple is determined by:
ΔVOUT
=
ΔIL
* ⎜⎜⎝⎛ ESRCOUT
+
1
8 * FOSC * COUT
⎟⎟⎠⎞
Where FOSC = operating frequency, COUT= output capacitance and ΔIL = ripple current in the inductor. For a
fixed output voltage, the output ripple is highest at maximum input voltage since ΔIL increases with input
voltage. A 22μF ceramic capacitor is recommended value in typical application.
Capacitor Value
(µF)
22
Recommend Table
Case Size
Component
Supplier
0805 1206
TDK
Model
C2012JB0J226M
Elite Semiconductor Memory Technology Inc.
Publication Date: Dec. 2013
Revision: 0.1
11/18
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet EML3173.PDF ] | |
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