A8167ATE6VR-020 [AITSEMI]
LED BACKLIGHT DRIVER;
| 型号： | A8167ATE6VR-020 |
| 厂家： | 
AiT Semiconductor |
| 描述： | LED BACKLIGHT DRIVER 驱动 |
| 文件： | 总15页 (文件大小：455K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
DESCRIPTION
FEATURES
The A8167A-020 is a step-up DC/DC converter
specifically designed for driving white LEDs with a
constant current. The internal MOSFET can
support up to 10 White LEDs for backlighting and
OLED power application, and the internal soft start
function can reduce the inrush current. The
A8167A-020 uses current mode, fixed frequency of
approximately 1.0MHz architecture to regulate the
LED current through an external current sense
resistor. The low feedback voltage of 200mV can
minimize power dissipation.
VIN Operating Range : 2.5V to 5.5V
Internal Power N-MOSFET Switch
Wide Range for PWM Dimming
(100Hz to200kHz)
1.0MHz Switch Frequency
200mV Feedback Voltage
1.2A SW Current Limit
Minimize the External Component Counts
Internal Compensation
Over Voltage Protection
Available in TSOT-26 and DFN8(2x2)Packages
Other features include current limit protection,
thermal shutdown protection, under-voltage lockout
(UVLO), and over-voltage function.
APPLICATION
Cellular Phones and Digital Cameras
The A8167A-020 is available in TSOT-26 and
DFN8(2x2) packages.
PDAs and Smart Phones and MP3 and OLED
Portable Instruments
High-light LED Flash
ORDERING INFORMATION
TYPICAL APPLICATION
Package Type
TSOT-26
Part Number
A8167ATE6R-020
TE6
J8
A8167ATE6VR-020
A8167AJ8R-020
A8167AJ8VR-020
DFN8 (2x2)
Note
V: Halogen free Package
R: Tape & Reel
AiT provides all RoHS products
Basic Application Circuit with A8167A-020
Suffix “ V “ means Halogen free Package
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 1 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
PIN DESCRIPTION
Top View
Top View
Function
Pin #
Symbol
SW
SOT-26
1
DFN8
8
Switching Pin.
Ground Pin. The exposed pad must be soldered to a
large PCB and connected to GND for maximum
power dissipation.
1,5,9
2
GND
(Exposed pad)
3
4
5
6
-
6
4
3
2
7
FB
EN
Feedback Pin.
Chip Enable (Active High).
Output Voltage Pin.
VOUT
VIN
Input Supply.
NC
No Internal Connection.
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 2 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
ABSOLUTE MAXIMUM RATINGS
VIN, Supply Input Voltage
SW, Switching Pin
-0.3V~6V
-0.3V~40V
-0.3V~40V
-0.3V~6V
VOUT
Other Pins
PD, Power Dissipation, @ TA = 25°C
TSOT-26
0.392W
0.606W
DFN8( 2x2)
Package Thermal Resistance NOTE3
θJA, TSOT-26
255°C/W
165°C/W
20°C/W
θJA, DFN8( 2x2)
θJC, DFN8( 2x2)
Lead Temperature (Soldering, 10 sec.)
Junction Temperature
Storage Temperature Range
260°C
150°C
-65°C~150°C
Stress beyond above listed “Absolute Maximum Ratings” may lead permanent damage to the device. These are stress ratings only and
operations of the device at these or any other conditions beyond those indicated in the operational sections of the specifications are not
implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONSNOTE2
Parameter
Junction Temperature Range
MIN
-40
-40
MAX
125
85
Units
°C
Ambient Temperature Range
°C
NOTE1: The device is not guaranteed to function outside its operating conditions.
NOTE2: θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of JEDEC
51-3 thermal measurement standard. The case point of θJC is on the expose pad for the WDFN package.
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 3 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
ELECTRICAL CHARACTERISTICS
VIN=3.7V, CIN=2.2uF, COUT=1uF, IOUT=20mA, L=10uH, TA = 25°C, unless otherwise specified
Parameter
Symbol
Conditions
Min.
2.5
2
Typ.
Max.
5.5
Unit
V
Input Voltage
VIN
Under Voltage Lock Out
UVLO Hystersis
Quiescent Current
Supply Current
VUVLO
2.2
0.1
400
1
2.45
V
V
IQ
IIN
FB = 1.5V, No Switching
FB = 0V, Switching
VEN < 0.4V
600
2
uA
mA
uA
%
Shutdown Current
Line Regulation
ISHDN
1
4
VIN = 3 to 4.3V
1
Load Regulation
Operation Frequency
Maximum Duty Cycle
Clock Rate
1mA to 20mA
1
%
fOSC
0.75
90
1
1.25
MHz
%
92
0.1
185
200
215
1.2
kHz
mV
Ω
Feedback Reference Voltage
On Resistance
VREF
200
0.7
RDS(ON)
EN Threshold
VIH
1.4
34
V
V
Logic-High Voltage
EN Threshold
VIL
IIH
0.5
38
Logic-Low Voltage
EN Sink Current
EN Hystersis
1
uA
V
0.1
36
Over-Voltage Threshold
Over-Current Threshold
OTP
VOVP
IOCP
V
1.2
160
30
A
TOTP
°C
°C
OTP Hystersis
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 4 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
TYPICAL PERFORMANCE CHARACTERISTICS
1.
3.
5.
η vs. VIN
2.
4.
6.
IQ vs. VIN
FOSC vs. VIN
VFB vs. VIN
VEN vs. VIN
ILED vs. DUTY
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 5 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
7.
VFB vs. ILED
8.
Power On from EN
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 6 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
BLOCK DIAGRAM
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 7 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
DETAILED INFORMATION
Applications Information
LED Current Setting
The loop of Boost structure will keep the FB pin voltage equal to the reference voltage VREF. Therefore, when
SET connects FB pin and GND, the current flows from VOUT through LED and RSET to GND will be decided by
R
the current on RSET, which is equal to following equation.
Dimming Control
a. Using a PWM Signal to EN Pin
For the brightness dimming control of the A8167A-020, the IC provides typically 200mV feedback voltage
when the EN pin is pulled constantly high. However, EN pin allows a PWM signal to reduce this regulation
voltage by changing the PWM duty cycle to achieve LED brightness dimming control. The relationship
between the duty cycle and FB voltage can be calculated as following equation.
VFB = Duty x 200mV
Where
Duty = duty cycle of the PWM signal
200mV = internal reference voltage
As shown in Figure 1, the duty cycle of the PWM signal is used to cut the internal 200mV reference voltage.
An internal low pass filter is used to filter the pulse signal. And then the reference voltage can be made by
connecting the output of the filter to the error amplifier for the FB pin voltage regulation.
However, the internal low pass filter 3db frequency is 500Hz. When the dimming frequency is lower then
500Hz, VA is also a PWM signal and the LED current is controlled directly by this signal. When the frequency
is higher than 500Hz, PWM is filtered by the internal low pass filter and the VA approach a DC signal. And the
LED current is a DC current which eliminate the audio noise.
Figure 1. Block Diagram of Programmable FB Voltage Using PWM Signal
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 8 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
b. Using a DC Voltage
Using a variable DC voltage to adjust the brightness is a popular method in some applications. The dimming
control using a DC voltage circuit is shown in Figure 2. As the DC voltage increases, the current flows through
R3 increasingly and the voltage drop on R3 increase, i.e. the LED current decreases. For example, if the VDC
range is from 0V to 2.8V and VREF is equal to 0.2V, the selection of resistors in Figure 2 sets the LED current
from 21.5mA to 0mA. The LED current can be calculated by the following equation.
Figure 2. Dimming Control Using a DC Voltage
c. Using a Filtered PWM signal
Another common application is using a filtered PWM signal as an adjustable DC voltage for LED dimming
control. A filtered PWM signal acts as the DC voltage to regulate the output current. The recommended
application circuit is shown as Figure 3. In this circuit, the output ripple depends on the frequency of PWM
signal. For smaller output voltage ripple (<100mV), the recommended frequency of 2.8V PWM signal should
be above 2kHz. To fix the frequency of PWM signal and change the duty cycle of PWM signal can get
different output current. The LED current can be calculated by the following equation.
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 9 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
Figure 3. Dimming Control Using a Filtered PWM Signal
By the above equation and the application circuit shown in Figure 3. We can get the relationship between the
LED current and PWM duty cycle. For example, when the PWM duty is equal to 60%, the LED current will be
equal to 8.6mA. When the PWM duty is equal to 40%, the LED current will be equal to 12.9mA.
Power Sequence
In order to assure the normal soft start function for suppressing the inrush current the input voltage should be
ready before EN pulls high.
Soft-Start
The function of soft-start is made for suppressing the inrush current to an acceptable value at the beginning of
power-on. The A8167A-020 provides a built-in soft-start function by clamping the output voltage of error
amplifier so that the duty cycle of the PWM will be increased gradually in the soft-start period.
Current Limiting
The current flow through inductor as charging period is detected by a current sensing circuit. As the value
comes across the current limiting threshold, the N-MOSFET will be turned off so that the inductor will be
forced to leave charging stage and enter discharging stage. Therefore, the inductor current will not increase
over the current limiting threshold.
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 10 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
OVP/UVLO/OTP
The Over Voltage Protection is detected by a junction breakdown detecting circuit. Once VOUT goes over the
detecting voltage, SW pin stops switching and the power N-MOSFET will be turned off. Then, the VOUT will be
clamped to be near VOVP. As the output voltage is higher than a specified value or input voltage is lower than a
specified value, the chip will enter protection mode to prevent abnormal function. As the die temperature is
higher then 160°C, the chip also will enter protection mode. The power MOSFET will be turned off during
protection mode to prevent abnormal operation.
Capacitor Selection
Input ceramic capacitor of 2.2uF and output ceramic capacitor of 1uF are recommended for the A8167A-020
applications for driving 10 series WLEDs. For better voltage filtering, ceramic capacitors with low ESR are
recommended. X5R and X7R types are suitable because of their wider voltage and temperature ranges.
Inductor Selection
The recommended value of inductor for 10 WLEDs applications is from 10uH to 47uH. Small size and better
efficiency are the major concerns for portable devices, such as the A8167A-020 used for mobile phone. The
inductor should have low core loss at 1.0MHz and low DCR for better efficiency. The inductor saturation
current rating should be considered to cover the inductor peak current.
Thermal Considerations
For continuous operation, do not exceed absolute maximum operation junction temperature. The maximum
power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surroundings
airflow and temperature difference between junction to ambient. The maximum power dissipation can be
calculated by following formula :
PD(MAX) = ( TJ(MAX) − TA ) /θJA
Where TJ(MAX) is the maximum operation junction temperature, TA is the ambient temperature and the θJA is
the junction to ambient thermal resistance.
For the recommended operating conditions specification of A8167A-020, the maximum junction temperature
of the die is 125°C. The junction to ambient thermal resistance θJA is layout dependent. The junction to
ambient thermal resistance for TSOT-26 package is 255°C/W and for DFN8( 2x2) package is 165°C/W on the
standard JEDEC 51-3 single layer thermal test board. The maximum power dissipation at TA = 25°C can be
calculated by following formula:
P
D(MAX) = (125°C − 25°C) / (165°C/W) = 0.606W for DFN8( 2x2) packages
D(MAX) = (125°C − 25°C) / (255°C/W) = 0.392W for TSOT-26 packages
P
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 11 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
The maximum power dissipation depends on operating ambient temperature for fixed TJ(MAX) and thermal
resistance θJA. For A8167A-020 packages, the Figure 4 of derating curves allows the designer to see the
effect or rising ambient temperature on the maximum power allowed.
Figure 4. Derating Curves for A8167A-020 Packages
Layout Consideration
For best performance of the A8167A-020, the following guidelines must be strictly followed.
Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce
noise coupling.
The GND and Exposed Pad should be connected to a strong ground plane for heat sinking and noise
protection.
Keep the main current traces as possible as short and wide.
SW node of DC-DC converter is with high frequency voltage swing. It should be kept at a small area.
Place the feedback components as close as possible to the IC and keep away from the noisy devices.
Typical Application Circuits
Figure 5. LED Backlighting
Figure 6. High-light LED Flash
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 12 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
PACKAGE INFORMATION
Dimension in TSOT-26 (Unit: mm)
Symbol
Min
Max
A
A1
A2
b
0.700
0.000
0.700
0.350
0.080
2.820
1.600
2.650
0.900
0.100
0.800
0.500
0.200
3.020
1.700
2.950
c
D
E
E1
e
0.950(BSC)
1.900(BSC)
e1
L
0.300
0°
0.600
8°
θ
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 13 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
Dimension in DFN8 (Unit: mm)
Symbol
Min
Max
A
A1
A3
b
0.700
0.000
0.175
0.200
1.950
1.000
1.950
0.400
0.900
0.050
0.250
0.300
2.050
1.250
2.050
0.650
D
D2
E
E2
e
0.500
L
0.300
0°
0.400
8°
θ
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 14 -
A8167A-020
AiT Semiconductor Inc.
LED BACKLIGHT DRIVER
SMALL PACKAGE, HIGH PERFORMANCE
www.ait-ic.com
ASYNCHRONIES BOOST FOR 10 WLED DRIVER
IMPORTANT NOTICE
AiT Semiconductor Inc. (AiT) reserves the right to make changes to any its product, specifications, to
discontinue any integrated circuit product or service without notice, and advises its customers to obtain the
latest version of relevant information to verify, before placing orders, that the information being relied on is
current.
AiT Semiconductor Inc.'s integrated circuit products are not designed, intended, authorized, or warranted to
be suitable for use in life support applications, devices or systems or other critical applications. Use of AiT
products in such applications is understood to be fully at the risk of the customer. As used herein may involve
potential risks of death, personal injury, or servere property, or environmental damage. In order to minimize
risks associated with the customer's applications, the customer should provide adequate design and
operating safeguards.
AiT Semiconductor Inc. assumes to no liability to customer product design or application support. AiT
warrants the performance of its products of the specifications applicable at the time of sale.
REV1.1
- JAN 2015 RELEASED, MAY 2016 UPDATED -
- 15 -
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