A8176 [AITSEMI]
LED DRIVER;
| 型号： | A8176 |
| 厂家： | 
AiT Semiconductor |
| 描述： | LED DRIVER 驱动 |
| 文件： | 总9页 (文件大小：352K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
DESCRIPTION
FEATURES
The A8176 is a constant frequency, SOT-25 current
mode step-up converter intended for small, low power
applications. The A8176 switches at 1.0MHz and
allows the use of tiny, low cost capacitors and
inductors 2mm or less in height. Internal soft-start
results in small inrush current and extends battery
life. The A8176 operates from an input voltage as low
as 3.0V and can generate 24V at up to 80mA from a
5V supply.
Integrated 0.7Ω Power MOSFET
400μA Quiescent Current
3.0V to 5.5V Input Voltage
1.0MHz Fixed Switching Frequency
Internal 1.2A Switch Current Limit
Adjustable Output Voltage
Internal Compensation
Up to 24V Output Voltage
Over 85% Efficiency
The A8176 includes current limiting, and thermal
overload protection to prevent damage in the event of
an output overload.
Available in SOT-25 Package
APPLICATION
OLED Biasing
LCD Bias Supply
White LED Driver
PDAs
The A8176 is available in SOT-25 package.
ORDERING INFORMATION
Digital Still Cameras
TYPICAL APPLICATION
Package Type
Part Number
A8176E5R
SOT-25
E5
SPQ: 3,000pcs/Reel
A8176E5VR
V: Halogen free Package
R: Tape & Reel
Note
AiT provides all RoHS products
Figure 1. Basic Application Circuit with A8176
REV1.1
- JUL 2013 RELEASED, MAY 2017 UPDATED -
- 1 -
A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
PIN DESCRIPTION
Top View
Pin #
Symbol
SW
Function
1
2
3
4
5
Switching Pin
Ground Pin
GND
FB
Feedback Pin. Feedback voltage is 1.23V
Chip Enable (Active High)
Input Supply
EN
VIN
ABSOLUTE MAXIMUM RATINGS
VIN, Supply Input Voltage
SW, Switching Pin
-0.3V~ 6V
-0.3V~ 30V
-0.3V~ 6V
0.392W
Other Pins
PD, Power Dissipation @ TA=25°C
Package Thermal Resistance NOTE 1
SOT-25, θJA
SOT-25
255°C/W
260°C
Lead Temperature (Soldering, 10 sec.)
Junction Temperature
150°C
Storage Temperature Range
-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.
NOTE1: 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.
REV1.1
- JUL 2013 RELEASED, MAY 2017 UPDATED -
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A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
RECOMMENDED OPERATING CONDITIONSNOTE2
Parameter
Min.
-40
Max.
125
85
Units
°C
Junction Temperature Range
Ambient Temperature Range
-40
°C
NOTE2: The device is not guaranteed to function outside its operating conditions.
ELECTRICAL CHARACTERISTICS
VIN=3.7V, TA = 25°C, unless otherwise specified
Parameter
Operating Input Voltage
Under Voltage Lockout
Under Voltage Lockout Hysteresis
Current (Shutdown)
Quiescent Current
Conditions
Min.
Typ.
-
Max.
Unit
3
5.5
V
V
2
2.2
100
1
2.45
-
-
mV
uA
uA
mA
MHz
%
VEN=0V
-
5
VFB=1.5V,NO switch
VFB=0V,switch
-
400
1
600
Supply Current
-
2
Switching Frequency
Maximum Duty Cycle
EN Input High Voltage
EN Input Low Voltage
FB Voltage
0.75
1
1.25
VFB=0V
90
92
-
-
1.4
-
V
-
-
0.5
V
1.193
1.23
-10
0.7
1.2
-
1.267
V
FB Input Bias Current
SW ON Resistance
SW Current Limit
VFB=1.23V
-
-
-
-
-
-
-
-
-
nA
Ω
VIN=3.7V, Duty Cycle=50%
VSW=24V
-
A
SW Leakage
1
-
uA
us
°C
°C
Soft Start
200
160
40
Over Temperature Shutdown
Over Temperature Hysteresis
-
-
REV1.1
- JUL 2013 RELEASED, MAY 2017 UPDATED -
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A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
TYPICAL PERFORMANCE CHARACTERISTICS
1.
3.
5.
Iq vs. VIN
2.
4.
6.
f vs. VIN
VFB vs. VIN
VEN vs. VIN
Power On/Off from EN (CH1:EN,CH2:VO)
Normal Operation (CH1:SW,CH2:VO,CH4:ISW)
REV1.1
- JUL 2013 RELEASED, MAY 2017 UPDATED -
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A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
7.
η vs. IO
BLOCK DIAGRAM
REV1.1
- JUL 2013 RELEASED, MAY 2017 UPDATED -
- 5 -
A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
DETAILED INFORMATION
Setting the Output Voltage
The internal reference VREF is 1.23V (Typical).The output voltage is divided by a resistor divider, R2 and R1 to
the FB pin. The output voltage is given by
R2
R1
VOUT =1.23V x 1+
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 A8176 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.
Capacitor Selection
Input ceramic capacitor of 10uF and output ceramic capacitor of 10uF are recommended for the A8176
applications. 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 are 4.7 to 22μH. Small size and better efficiency are the major concerns
for portable device. Small size and better efficiency are the major concerns for portable devices, such as the
A8176 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.
REV1.1
- JUL 2013 RELEASED, MAY 2017 UPDATED -
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A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
Diode Selection
Schottky diode is a good choice for A8176 because of its low forward voltage drop and fast reverse recovery.
Using Schottky diode can get better efficiency. The high speed rectification is also a good characteristic of
Schottky diode for high switching frequency. Current rating of the diode must meet the root mean square of
the peak current and output average current multiplication as following:
ID(RMS)
≈
IOUTxIPEAK
The diode’ s reverse breakdown voltage should be larger than the output voltage.
Layout Consideration
For best performance of the A8176, 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 2 LCD Display Power
REV1.1
- JUL 2013 RELEASED, MAY 2017 UPDATED -
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A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
PACKAGE INFORMATION
Dimension in SOT-25 (Unit: mm)
Millimeters
Inches
Symbol
Min
Max
Min
Max
A
A1
A2
b
1.050
0.000
1.050
0.300
0.100
2.820
1.500
2.650
1.250
0.100
1.150
0.500
0.200
3.020
1.700
2.950
0.041
0.000
0.041
0.012
0.004
0.111
0.059
0.104
0.049
0.004
0.045
0.020
0.008
0.119
0.067
0.116
c
D
E
E1
e
0.950(BSC)
0.037(BSC)
e1
L
1.800
0.300
0°
2.000
0.600
8°
0.071
0.012
0°
0.079
0.024
8°
θ
REV1.1
- JUL 2013 RELEASED, MAY 2017 UPDATED -
- 8 -
A8176
AiT Semiconductor Inc.
LED DRIVER
www.ait-ic.com
1.0MHz, 1.2A UP TO 24V OUTPUT MICROPOWER
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 server 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
- JUL 2013 RELEASED, MAY 2017 UPDATED -
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