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PDF RT9277B Data sheet ( Hoja de datos )
| Número de pieza | RT9277B | |
| Descripción | Low Noise Boost Converter | |
| Fabricantes | Richtek | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de RT9277B (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
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RT9277A/B
High Performance, Low Noise Boost Converter
General Description
The RT9277A/B is a high performance, low noise, fixed
frequency step up DC-DC Converter. The RT9277A/B
converters input voltage ranging 2.5V to 5.5V into output
voltage up to 16V. Current mode control with external
compensation network makes it easy to stabilize the
system and keep maximum flexibility. Soft start function
minimizes impact on the input power system. Internal power
MOSFET with very low RDS(ON) provides high efficiency.
The RT9277A/B automatically transits from PWM to PSM
(Pulse Skipping Mode) during light load condition further
increasing efficiency. 640kHz and 1.2MHz operation
frequency options provide flexibiltity of minimum output
inductor size, maximum efficiency and low BOM cost.
The RT9277A/B also provides comprehensive protection
functions such as UVLO, OCP and OTP.
Features
z 90% Efficiency
z VIN Operating Range : 2.5V to 5.5V
z 1.6A, 0.2Ω, 16V Internal Power MOSFET
z 640kHz and 1.2MHz Operation Frequency
z External Compensation Network
z Internal/External Programmable Soft Start Function
z Small MSOP8 Package
z OCP and OTP Function are Included
z RoHS Compliant and 100% Lead (Pb)-Free
Applications
z TFT LCD panel
z OLEDDisplay
z PCMCIA Cards
z Portable Device
Ordering Information
RT9277A/B
Package Type
F : MSOP-8
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
Soft Start Function
A : Internal
B : External Programmable
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.
Pin Configurations
(TOP VIEW)
COMP
FB
EN
GND
18
27
36
45
RT9277A
COMP
FB
EN
GND
18
27
36
45
RT9277B
Marking Information
MSOP-8
For marking information, contact our sales representative
directly or through a RichTek distributor located in your
area.
NC
FREQ
VIN
LX
SS
FREQ
VIN
LX
DS9277A/B-04 April 2011
www.richtek.com
1
1 page  
RT9277A/B
Absolute Maximum Ratings (Note 1)
z Supply Voltage (VIN) ------------------------------------------------------------------------------------------------ −0.3 to 6V
z LX to GND ------------------------------------------------------------------------------------------------------------- − 0.3V to 16V
z The other pins -------------------------------------------------------------------------------------------------------- − 0.3V to 6V
z Power Dissipation, PD @ TA = 70°C
MSOP-8 --------------------------------------------------------------------------------------------------------------- 625mW
z Package Thermal Resistance (Note 2)
MSOP-8, θJA ---------------------------------------------------------------------------------------------------------- 160°C/W
z Junction Temperature ----------------------------------------------------------------------------------------------- 150°C
z Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260°C
z Storage Temperature Range --------------------------------------------------------------------------------------- − 65°C to 150°C
z ESD Susceptibility (Note 3)
HBM (Human Body Mode) ----------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------ 200V
Recommended Operating Conditions (Note 4)
z Junction Temperature Range -------------------------------------------------------------------------------------- −40°C to 125°C
z Ambient Temperature Range -------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VIN = 3V, FREQ left floating, TA = 25°C, Unless Otherwise specification)
Parameter
Symbol
Test Conditions
System Supply Input
Operation Voltage Range
VIN
Under Voltage Lock Out
UVLO
Power On Reset Hysteresis
Quiescent Current
IQ
Shut Down Current
ISHDN
Soft start Current (RT9277B) ISS
Switching Regulator Oscillator
VFB = 1.3V, No switching
VFB = 1.0V, Switching, No load
EN = GND
VSS = 1.2V
Free Run Frequency
Maximum Duty Cycle
Reference Voltage
fOSC
FREQ = GND
FREQ = VIN
Feedback Reference Voltage
Error Amplifier
VREF
VCOMP = 1.24V
Transconductance
Voltage Gain
Gm
AV
Min Typ Max Unit
2.5 -- 5.5 V
1.9 2 2.1 V
-- 100 -- mV
-- 250 350 uA
-- 2 5 mA
-- -- 1 uA
1.5 4
7 uA
540 640 740
kHz
-- 1200 --
82 90 96 %
1.222 1.24 1.258 V
70 140 240 uΩ
-- 700 -- V/V
To be continued
DS9277A/B-04 April 2011
www.richtek.com
5
5 Page 
R3 = 200 × VOUT2 × C2
L1
C3 = 0.4 ×10-3 × L1
VIN
C4 = 0.005 × RESR × L1
VOUT 2
The best criterion to optimize the loop compensation is
by inspecting the transient response and adjusting the
compensation network.
Soft-Start Capacitor
The soft-start function begins from VSS = 0V to VSS = 1.24V
with a 4μA constant current charging to the soft-start
capacitor, so the capacitor should be large enough to let
the output voltage reach regulation inside the soft-start
cycle. Typical value of soft-start capacitor range is from
10nF to 200nF. After the cycle finished, the load can start
to draw maximum current as required.
Layout Guideline
For high frequency switching power supplies, the PCB
layout is important step in system application design. In
order to let IC achieve good regulation, high efficiency and
stability, it is strongly recommended the power
components should be placed as close as possible. These
traces should be wide and short. The feedback pin and the
networks of feedback and compensation should keep away
from the power loops, and be shielded with a ground trace
or plane to prevent noise coupling.
RT9277A/B
DS9277A/B-04 April 2011
www.richtek.com
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet RT9277B.PDF ] | |
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