|
|
PDF RT9287A Data sheet ( Hoja de datos )
| Número de pieza | RT9287A | |
| Descripción | Boost Converter | |
| Fabricantes | Richtek Technology | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de RT9287A (archivo pdf) en la parte inferior de esta página. Total 14 Páginas | ||
|
No Preview Available !
Preliminary
RT9287A
Boost Converter for WLED Power with Dual LDO
General Description
The RT9287A is an integrated solution for WLED and
camera power. It contains a boost converter with internal
schottky diode to provide WLED power and Dual LDO for
the power of camera image sensor.
In the section of boost converter, RT9287A's optimized
operation frequency can meet the requirement of small
LC filters value and low operation current with high
efficiency. Internal soft start function can reduce the inrush
current. The initial current of WLED is set by the external
resistor RSET. The feedback voltage is 250mV.
In the section of DLDO, RT9287A is a dual channel, low
noise, and low dropout regulator sourcing up to 300mA at
each channel. The part offers 2% accuracy, low dropout
voltage (240mV@300mA), and low ground current, only
27μA per LDO. The shutdown current is near zero current,
which is suitable for battery-power devices. Other features
include current limiting, over temperature, output short
circuit protection. The part is short circuit thermal folded
back protected. RT9287A lowers its OTP trip point from
165°C to 110°C when output short circuit occurs (VOUT <
0.4V) providing maximum safety to end users.
RT9287A is available in a WDFN-12L 3x3 package.
Ordering Information
RT9287A-
Package Type
QW : WDFN-12L 3x3 (W-Type)
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
LDO Output Voltage : VOUT1/VOUT2
MG : 2.8V/1.8V
FQ : 1.5V/3.1V
Note :
RichTek Pb-free and Green 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.
`100% matte tin (Sn) plating.
www.DataSheet4U.com
DS9287A-00 July 2007
Features
z Boost Converter
`VIN Operating Range : 2.7V to 5.5V
`Up to 85% Efficiency
`22V Internal Power N-MOSFET
`1MHz Switching Frequency
`Built-in Diode
`Digital Dimming with Zero-Inrush
`Input UVLO Protection
`Output Over Voltage Protection
`Internal Soft Start and Compensation
z Dual LDO
`Wide Operating Voltage Ranges : 2.7V to 5.5V
`Low-Noise for RF Application
`No Noise Bypass Capacitor Required
`Fast Response in Line/Load Transient
`TTL-Logic-Controlled Shutdown Input
`Low Temperature Coefficient
`Dual LDO Outputs (300mA/300mA)
`Ultra-Low Quiescent Current 27μA/LDO
`High Output Accuracy 2%
`Short Circuit Protection
`Thermal Shutdown Protection
`Current Limit Protection
`Short Circuit Thermal Folded Back Protection
z RoHS Compliant and 100% Lead (Pb)-Free
Applications
z Cellular Phones
z WLEDDriver
z PDAs and Smart Phones
z Probable Instruments
Pin Configurations
(TOP VIEW)
VIN 1
EN1 2
EN2 3
LX 4
PGND 5
VOUT 6
12 VLDO1
11 VLDO2
GND
10 AGND
9 FB
8 VDD
7 ENB
WDFN-12L 3x3
www.richtek.com
1
1 page  
Preliminary
RT9287A
Par amete r
M OS FET
On Resistance of MOSFET
Protection
OVP Threshold
OCP
Control Interface
ENB
Logic-Low Voltage
Threshold Logic-High Voltage
ENB Low Time for Dimming
Delay Between Steps Time
Shut Down Delay Time
Dual LDO
Input Voltage
Dropout Voltage (Note 5)
Output Voltage Range
VOUT Accuracy
Line Regulation
Load Regulation
Current Limit
Quiescent Current
Shutdown Current
EN1,2 T hreshold
Output Voltage TC
Thermal Shutdown
Thermal Shutdown Hysteresis
PSRR ILOAD = 10mA
PSRR ILOAD = 150mA
Symbol
RDS(ON)
VOV P
Test Condition
VIL
VIH
TLO
THI
TSHDN
Refer to Figure 1
Refer to Figure 1
Refer to Figure 1
VIN
VDROP
VOUT
ΔV
ΔVLINE
ΔVLOAD
ILIM
IQ
ISHDN
VIH
VIL
VIN = 2.7V to 5.5V
IOUT = 300mA
IOUT = 1mA
VIN = (VOUT + 0.3V) to 5.5V or
VIN > 2.7V, whichever is larger
1mA < IOUT < 300mA
RLOAD = 1Ω
VEN1, 2 > 1.5V
VEN1, 2 < 0.4V
VIN = 2.7V to 5.5V, Power On
VIN = 2.7V to 5.5V, Shutdown
TSD
ΔTSD
PSRR
f = 100Hz
f = 1kHz
f = 10kHz
f = 100Hz
f = 1kHz
f = 10kHz
Min Typ Max Units
0.5 0.9
--
Ω
-- 20 --
-- 400 --
V
mA
-- -- 0.4 V
1.4 --
--
V
0.5 -- 300 μs
0.5 --
--
μs
1 -- -- ms
2.7 -- 5.5
-- 240 330
1.2 -- 3.6
−2 -- +2
V
mV
V
%
-- -- 0.2 %/V
-- -- 0.6 %
330 450 700
mA
-- 58 80
μA
-- -- 1
μA
1.5 --
--
V
-- -- 0.4 V
-- 100 -- ppm/°C
-- 170
--
°C
-- 40
--
°C
-- −65 --
-- −60 --
dB
dB
-- −50 --
-- −65 --
-- −50 --
-- −50 --
dB
dB
dB
dB
DS9287A-00 July 2007
www.richtek.com
5
5 Page 
Preliminary
RT9287A
Application Information
Boost Converter
LED Current Control
As shown in Figure 1, the RT9287A regulates the LED
current by setting the current sense resistor (RSET)
connected between FB pin and ground. The reference
voltage of FB pin is 0.25V in typical. The LED current
(ILED) can be calculated by the following Equation.
ILED = VREF / RSET
(1)
In order to have an accurate LED current, a precision
resistor is preferred (1% is recommended).
Chip Enable
VIN
2.7V to 5.5V
L1
10uH to 22uH
RT9287A
LX VDD
EN VOUT
PGND FB
C1
1uF
VFB = 0.25V
RSET
Figure 1. Application for Driving 3 series WLEDs
VOUT = RA x {(FB/RB) + (FB-GPIO)/RGPIO} + FB
As GPIO = 0V,
VOUT = RA x {(0.25/RB) + (0.25/RGPIO)} + 0.25
As GPIO = 2.8V,
VOUT = RA x {(0.25/RB) + (0.25-2.8)/RGPIO} + 0.25
As GPIO = 1.8V,
VOUT = RA x {(0.25/RB) + (0.25-1.8)/RGPIO} + 0.25
For Efficiency Consideration set RA = 990kΩ.
(3)
(4)
(5)
(6)
Table 1. Suggested Resistance for Output Voltage
Control
Conditions
Case A :
Normal Voltage = 16V
(GPIO = 0V)
Dimming Voltage = 12V
(GPIO = 1.8V)
Case B :
Normal Voltage = 16V
(GPIO = 0V)
Dimming Voltage = 12V
(GPIO = 2.8V)
RA
(kΩ)
RB RGPIO
(kΩ) (kΩ)
1100 18 495
1200 19.5 840
Inductor Selection
The recommended value of the inductor is from 10μH to
22μH for 4 to 5 WLEDs applications. For 3WLEDs, the
recommended value of the inductor is from 4.7μH to 22μH.
Small size and better efficiency are the major concerns
for portable devices, just as RT9287A's application for
mobile phone. The inductor should have low core loss at
1MHz and low DCR for better efficiency.
The inductor saturation current rating should be considered
to cover the inductor peak current.
Output Voltage Control
For fixed output voltage application, the output voltage
can be adjusted by the divider circuit on FB pin. Figure2
shows a 2-level voltage control circuit for OLED application.
The output voltage can be calculated by the following
equations. Table 1 is the recommended resistance for
different conditions.
VIN
VEN
VDD VOUT
RT9287A
LX FB
ENB
PGND
GPIO
RA RGPIO
RB
OLED
Figure 2. Application Circuit for 2-level Output Voltage
Control
Dual LDO
Like any low-dropout regulator, the external capacitors used
with the RT9287A must be carefully selected for regulator
stability and performance. Using a capacitor whose value
is > 1μF on the LDO input and the amount of capacitance
can be increased without limit. The input capacitor must
be located a distance of not more than 0.5 inch from the
input pin of the IC and returned to a clean analog ground.
Any high quality ceramic or tantalum capacitor can be
DS9287A-00 July 2007
www.richtek.com
11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet RT9287A.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| RT9287 | Boost Converter | Richtek Technology |
| RT9287A | Boost Converter | Richtek Technology |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |