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PDF RT8025 Data sheet ( Hoja de datos )
| Número de pieza | RT8025 | |
| Descripción | High Efficiency PWM Step-Down DC/DC Converter | |
| Fabricantes | Richtek | |
| Logotipo |  |
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RT8025
1.25MHz, 400mA, High Efficiency PWM Step-Down
DC/DC Converter
General Description
Features
The RT8025 is a high-efficiency pulse-width-modulated
(PWM) step-down DC/DC converter. Capable of delivering
400mA output current over a wide input voltage range from
2.5 to 5.5V, the RT8025 is ideally suited for portable
electronic devices that are powered from 1-cell Li-ion
battery or from other power sources within the range such
as cellular phones, PDAs and handy-terminals.
Internal synchronous rectifier with low RDS(ON) dramatically
reduces conduction loss at PWM mode. No external
Schottky diode is required in practical application. The
RT8025 automatically turns off the synchronous rectifier
while the inductor current is low and enters discontinuous
PWM mode. This can increase efficiency at light load
condition.
The RT8025 enters Low-Dropout mode when normal PWM
cannot provide regulated output voltage by continuously
turning on the upper P-MOSFET. RT8025 enter shutdown
mode and consumes less than 0.1μA when EN pin is pulled
low.
The switching ripple is easily smoothed-out by small
package filtering elements due to a fixed operation
frequency of 1.25MHz. This along with small SOT-23-5
and TSOT-23-5 package provides small PCB area
application. Other features include soft start, lower internal
reference voltage with 2% accuracy, over temperature
protection, and over current protection.
Pin Configurations
(TOP VIEW)
LX FB/VOUT
54
23
VIN GND EN
SOT-23-5/TSOT-23-5
2.5V to 5.5V Input Range
Adjustable Output From 0.5V to VIN
1.0V, 1.2V, 1.3V, 1.5V, 1.8V, 2.5V and 3.3V Fixed/
Adjustable Output Voltage
400mA Output Current
95% Efficiency
No Schottky Diode Required
1.25MHz Fixed Frequency PWM Operation
Small SOT-23-5 and TSOT-23-5 Package
RoHS Compliant and Halogen Free
Applications
Cellular Telephones
Personal Information Appliances
Wireless and DSL Modems
MP3 Players
Portable Instruments
Ordering Information
RT8025(- )
Package Type
B : SOT-23-5
J5 : TSOT-23-5
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Output Voltage
Default : Adjustable
10 : 1.0V
12 : 1.2V
13 : 1.3V
15 : 1.5V
18 : 1.8V
25 : 2.5V
33 : 3.3V
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
DS8025-02 March 2011
www.richtek.com
1
1 page  
RT8025
Parameter
Symbol
Test Conditions
Output Voltage
Accuracy
FB Input Current
Adjustable
ΔVOUT
IFB
VIN = VOUT + ΔV to 5.5V
0A < IOUT < 400mA
VFB = VIN
(Note 5)
RDS(ON) of P-Channel MOSFET RDS(ON)_P IOUT = 200mA
VIN = 3.6V
VIN = 2.5V
RDS(ON) of N-Channel MOSFET RDS(ON)_N IOUT = 200mA
VIN = 3.6V
VIN = 2.5V
P-Channel Current Limit
ILIM_P
VIN = 2.5V to 5.5 V
EN High-Level Input Voltage
VEN_H
VIN = 2.5V to 5.5V
EN Low-Level Input Voltage
VEN_L
VIN = 2.5V to 5.5V
Undervoltage Lock Out threshold
Min
−3
−50
--
--
--
--
1
1.5
--
--
Typ
--
--
0.3
0.4
0.25
0.35
--
--
--
1.8
Max Unit
3%
50 nA
0.65
0.80 Ω
0.55
Ω
0.65
1.8 A
-- V
0.4 V
-- V
Hysteresis
-- 0.1 --
V
Oscillator Frequency
Thermal Shutdown Temperature
Min. On Time
fOSC
TSD
VIN = 3.6V, IOUT = 100mA
0.8 1.25 1.85 MHz
-- 160 -- °C
-- 50 -- ns
Max. Duty Cycle
100 --
-- %
LX Leakage Current
VIN = 3.6V, VLX = 0V or VLX = 3.6V -1
--
1 μA
Note 1. Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective thermal conductivity test board of
JEDEC 51-3 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Note 5. ΔV = IOUT x RDS(ON)_P
DS8025-02 March 2011
www.richtek.com
5
5 Page 
` Connect feedback network behind the output capacitors.
Keep the loop area small. Place the feedback
components near the RT8025.
` Connect all analog grounds to a command node and
then connect the command node to the power ground
behind the output capacitors.
RT8025
VIN
1
RT8025
VIN LX
5
L1
4.7uH
R3
C1
VOUT
R1
C3
4.7uF
3 EN
FB 4
GND
C4
C2 R2 10uF
2
Figure 6. EVB Schematic
Recommended component selection for Typical Application
Table 1. Inductors
Component Supplier Series Inductance (μH)
TAIYO YUDEN NR 3015
2.2
TAIYO YUDEN NR 3015
4.7
Sumida
CDRH2D14
2.2
Sumida
CDRH2D14
4.7
GOTREND
GTSD32
2.2
GOTREND
GTSD32
4.7
DCR (mΩ)
60
120
75
135
58
146
Current Rating (mA) Dimensions (mm)
1480
3x3x1.5
1020
3x3x1.5
1500
4.5x3.2x1.55
1000
4.5x3.2x1.55
1500
3.85x3.85x1.8
1100
3.85x3.85x1.8
Component Supplier
TDK
TDK
MURATA
MURATA
MURATA
TAIYO YUDEN
TAIYO YUDEN
TAIYO YUDEN
Table 2. Capacitors for CIN and COUT
Part No.
C1608JB0J475M
C2012JB0J106M
GRM188R60J475KE19
GRM219R60J106ME19
GRM219R60J106KE19
JMK107BJ475RA
JMK107BJ106MA
JMK212BJ106RD
Capacitance (μF)
4.7
10
4.7
10
10
4.7
10
10
Case Size
0603
0805
0603
0805
0805
0603
0603
0805
DS8025-02 March 2011
www.richtek.com
11
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet RT8025.PDF ] | |
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