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PDF RT8270 Data sheet ( Hoja de datos )
| Número de pieza | RT8270 | |
| Descripción | 1.2MHz Step-Down Converter | |
| Fabricantes | Richtek | |
| Logotipo |  |
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RT8270
2A, 22V, 1.2MHz Step-Down Converter
General Description
The RT8270 is an asynchronous high voltage buck
converter that can support the input voltage range from
4.75V to 22V and the output current can be up to 2A.
Current Mode operation provides fast transient response
and eases loop stabilization.
The chip provides protection functions such as cycle-by-
cycle current limiting and thermal shutdown protection.
In shutdown mode, the regulator draws 25μA of supply
current. The RT8270 is available in a SOP-8 surface mount
package.
Ordering Information
RT8270
Package Type
S : SOP-8
Note :
Lead Plating System
G : Green (Halogen Free and Pb Free)
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, otherwise visit our website for detail.
Features
z Wide Operating Input Range : 4.75V to 22V
z Adjustable Output Voltage Range : 1.222V to 16V
z Output Current up to 2A
z 25μA Low Shutdown Current
z Power MOSFET : 0.18Ω
z High Efficiency up to 95%
z 1.2MHz Fixed Switching Frequency
z Stable with Low ESR Output Ceramic Capacitors
z Thermal Shutdown Protection
z Cycle-By-Cycle Over Current Protection
z RoHS Compliant and Halogen Free
Applications
z Distributive Power Systems
z Battery Charger
z DSL Modems
z Pre-regulator for Linear Regulators
Pin Configurations
http://www.DataSheet4U.net/
(TOP VIEW)
BOOT
VIN
SW
GND
2
3
4
8 NC
7 EN
6 COMP
5 FB
SOP-8
Typical Application Circuit
VIN
4.75V to 22V
Chip Enable
CIN
10µF
2 VIN
BOOT 1
RT8270
SW 3
7 EN
FB 5
4 GND
COMP 6
CB L1
10nF 4.7µH
D1
B330
RC
18k
CC
1.8nF
R1
17k
R2
10k
VOUT
3.3V/2A
COUT
22µF
CP
NC
DS8270-01 March 2011
www.richtek.com
1
datasheet pdf - http://www.DataSheet4U.net/
1 page  
Typical Operating Characteristics
Efficiency vs. Output Current
100
90
80 VIN = 4.75V
70 VIN = 12V
VIN = 22V
60
50
40
30
20
10
0
0
VOUT = 3.3V
0.4 0.8 1.2 1.6
Output Current (A)
2
RT8270
Reference Voltage vs. Input Voltage
1.226
1.224
1.222
1.220
1.218
1.216
1.214
4
VIN = 4.75V to 22V, VOUT = 3.3V
7 10 13 16 19 22
Input Voltage (V)
Output Voltage vs. Output Current
3.300
3.297
3.294
3.291
3.288
3.285
VIN = 9V
VIN = 12V
VIN = 22V
3.282
3.279
0
VOUT = 3.3V
0.4 0.8 1.2 1.6
Output Current (A)
2
3.400
Output Voltage vs. Temperature
3.375
3.350
3.325
http://www.DataSheet4U.net/
3.300
3.275
3.250
3.225
3.200
-50
-25
VIN = 12V, VOUT = 3.3V, IOUT = 0A
0 25 50 75
Temperature (°C)
100 125
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
4
Frequency vs. Input Voltage
VIN = 4.75V to 22V, VOUT = 3.3V
6 8 10 12 14 16 18 20 22
Input Voltage (V)
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
-50
Frequency vs. Temperature
VIN = 12V, VOUT = 3.3V
-25 0 25 50 75 100 125
Temperature (°C)
DS8270-01 March 2011
www.richtek.com
5
datasheet pdf - http://www.DataSheet4U.net/
5 Page 
RT8270
Input capacitor must
be placed as close
to the IC as possible.
CIN
VIN
L1
SW
CB
BOOT
VIN
SW
D1 GND
COUT
VOUT
2
3
4
GND
CC
The feedback and
compensation components
must be connected as close
to the device as possible.
8 NC
7 EN
CP RC
6 COMP
R1
5 FB
VOUT
R2
GND
SW should be connected to inductor by
wide and short trace. Keep sensitive
components away from this trace.
Figure 4. PCB Layout Guide
Table 2. Suggested Inductors for Typical Application Circuit
Component Supplier
Series
Dimensions (mm)
TDK
SLF12555T 12.5 x 12.5 x 5.5
TAIYO YUDEN
NR8040
8x 8 x 4
TDK
SLF12565T 12.5 x 12.5 x 6.5
Table 3. Suggested Capacitors for CIN and COUT
Location Component Supplier
Part No.
CIN
MURATA
http://www.DataSheet4U.net/
GRM31CR61E106K
CIN TDK C3225X5R1E106K
CIN TAIYO YUDEN TMK316BJ106ML
COUT
MURATA
GRM32ER61E226M
COUT
TDK
C3225X5R0J226M
COUT
TAIYO YUDEN
EMK325BJ226MM
Capacitance (μF)
10
10
10
22
22
22
Case Size
1206
1206
1206
1210
1210
1210
Table 4. Suggested Diode
Component Supplier Series
DIODES
B330A
PANJIT
SK23
VRRM (V)
30
30
IOUT (A)
3
2
Package
SMA
DO-214AA
DS8270-01 March 2011
www.richtek.com
11
datasheet pdf - http://www.DataSheet4U.net/
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet RT8270.PDF ] | |
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