A7320AM8R [AITSEMI]
DC-DC CONVERTER/ BUCK SYNCHRONOUS PFM/PWM BUCK CONVERTER;
| 型号： | A7320AM8R |
| 厂家： | 
AiT Semiconductor |
| 描述： | DC-DC CONVERTER/ BUCK SYNCHRONOUS PFM/PWM BUCK CONVERTER DC-DC转换器 |
| 文件： | 总12页 (文件大小：362K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
DESCRIPTION
FEATURES
The A7320A is a high efficiency current-mode
synchronous, 18V/2A buck converter. Its input
voltage ranges from 4.5V to 18V and it provides an
adjustable regulated output voltage from 0.923V to
15V while delivering up to 2A of output current.
Adjustable Output Voltage, VFB=0.923V
Maximum output current is 2A
Range of operation input voltage: Max 18V
Withstand input voltage spike >30V
Standby current: 1mA (typ.)
Operating current at zero load: 1.2mA (typ.)
Line regulation: 0.1%/V (typ.)
The internal synchronous switches increase
efficiency and eliminate the need for an external
Schottky diode. The switching frequency is set to
340KHz. And the A7320A will automatically switch
between PFM and PWM mode based on the load
current, thus to enhance the converter efficiency at
light load.
Load regulation: 10mV (typ.)
High efficiency, up to 95%
Environment Temperature: -20°C ~ 85°C
Available in SOP8 and PSOP8 Packages
APPLICATION
Set-top-box
A7320A consists of many protection block such as
UVLO, input voltage over voltage protection to stand
much higher input voltage spike, thermal protection
and output short circuit protection.
Consumer Electronic Device for automobile
LCD Monitor and LCD TV
Portable DVD
ADSL Modem, WLAN router
Other 12V or double cell Li-ion battery powered
device
The A7320A is available in SOP8 and PSOP8
packages.
TYPICAL APPLICATION
ORDERING INFORMATION
Package Type
SOP8
Part Number
A7320AM8R
M8
A7320AM8VR
A7320AMP8R
A7320AMP8VR
PSOP8
Note
MP8
R: Tape & Reel
V: Halogen free Package
* When VIN is as low as 5V, CC is recommended to be 100pf, but
not needed when Vin larger than 5V.
AiT provides all RoHS products
Suffix “ V “ means Halogen free Package
REV1.0
- JUN 2012 RELEASED -
- 1 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
PIN DESCRIPTION
Top View
Symbol
Top View
Function
Pin #
SOP8
1
PSOP8
1
BST
VIN
High side power transistor gate drive boost input
Power input, the input capacitor should be placed as close to VIN and
GND pin as possible
2
2
3
4
5
3
4
5
SW
GND
FB
Power switching node to connect inductor
Ground.
Feedback input with reference voltage set to 0.923
Compensation node. A serial RC connected to this pin is required to
maintain the Buck converter control loop stable.
Enable input. Setting it to high level or connecting to VIN via a resistor
may turn on the chip, while setting it to ground level will turn off the
chip.
6
7
8
6
7
8
COMP
EN
Soft-start node. Connecting a 0.1uF capacitor to ground make the
Buck converter output rise smoothly.
SS
REV1.0
- JUN 2012 RELEASED -
- 2 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
ABSOLUTE MAXIMUM RATINGS
Max Input Voltage
30V
125°C
TJ, Max Operating Junction Temperature
TA, Ambient Temperature
-20°C ~ 85°C
SOP8
45°C/W
10°C/W
θJC, Package Thermal Resistance
PSOP8
TS, Storage Temperature
Lead Temperature & Time
ESD (HBM)
-40°C ~ 150°C
260°C,10S
>2000V
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 CONDITIONS
Input Voltage Range
Max. 18V
TJ, Operating Junction Temperature
-20°C ~ 125°C
REV1.0
- JUN 2012 RELEASED -
- 3 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
ELECTRICAL CHARACTERISTICS
VIN=12V, TA=25°C
Parameter
Input Voltage Range
Feedback Voltage
Symbol
VDD
Conditions
Min.
4.5
Typ.
Max.
18
Unit
V
VREF
IFB
VIN=12V, VEN=5V
0.900 0.923 0.946
V
Feedback Leakage current
0.1
1.1
6
0.4
1.5
10
uA
Active, VFB=1V, No Switching
Shutdown, VIN=8V
VIN=5V to 12V
mA
uA
Quiescent Current
IQ
Line Regulation
LnReg
LdReg
FSOC
0.1
0.02
340
130
110
2.5
1.5
%/V
%/A
KHz
mohm
mohm
A
Load Regulation
IOUT=0.1 to 2A
Switching Frequency
PMOS Rdson
VEN=2V, VIN=12V
RdsonP
RdsonN
Ilimit
NMOS Rdson
Peak Current Limit
EN High Threshold
EN Low Threshold
Input Over-Voltage Protection
Over Temperature Protection
VENH
1
2
V
VENL
0.5
V
VOVP
VEN=2V
18
V
TSD
160
°C
REV1.0
- JUN 2012 RELEASED -
- 4 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
VIN=12V, VOUT=3.3V, L=10uH, CIN=10uF, COUT=22uF, TA=25°C, unless otherwise stated
1.
3.
5.
Efficiency (VOUT=3.3V)
2.
4.
6.
VOUT Vs. IOUT
VOUT Vs. VIN
Zero Load Operating Current Vs. VIN
Switching waveform VIN=18V, IOUT=0
Switching waveform VIN=18V, IOUT=2A
REV1.0
- JUN 2012 RELEASED -
- 5 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
7.
Switching waveform VIN=5V, IOUT=0
8.
Switching waveform VIN=5V, IOUT=2A
REV1.0
- JUN 2012 RELEASED -
- 6 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
BLOCK DIAGRAM
REV1.0
- JUN 2012 RELEASED -
- 7 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
DETAILED INFORMATION
Functional Descriptions
Loop Operation
The A7320A is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of
delivering up to 2A of output current, integrated with a 110mΩ synchronous MOSFET, eliminating the need for
external diode. It uses a PWM current-mode control scheme. An error amplifier integrates error between the
FB signal and the internal reference voltage. The output of the integrator is then compared to the sum of a
current-sense signal and the slope compensation ramp. This operation generates a PWM signal that
modulates the duty cycle of the power MOSFETs to achieve regulation for output voltage.
Current Limit
There is a cycle-by-cycle current limit on the high-side MOSFET of 3A(typ). When the current flowing out of
SW exceeds this limit, the high-side MOSFET turns off and the synchronous rectifier turns on. Unlike the
traditional method of current limiting by limiting the voltage at the compensation pin, which usually has large
variation due to duty cycle variance, this type of peak current limiting scheme provides a relatively more
accurate limit for output current, thereby lowering the requirements for system design.
Light Load Operation
Traditionally, a fixed current mode constant frequency PWM DC-DC regulator always switches even when the
output load is small. When energy is shuffling back and forth through the power MOSFETs, power is lost due
to the finite RDSONs of the MOSFETs and parasitic capacitances. At light load, this loss is prominent and
efficiency is therefore very low. A7320A employs a proprietary control scheme that improves efficiency in this
situation by enabling the device into a power save mode during light load, thereby extending the range of high
efficiency operation.
Faster Transient Response
Normally, people use 3.3nF and 5.6Kohm RC for compensation to keep the loop stable. However, if one
needs to have faster load transient response, 3.3nF and 8.5Kohm is recommended.
REV1.0
- JUN 2012 RELEASED -
- 8 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
Component Selection
When setting up the A7320A for different output voltage, please use following recommended component
value for the best performance.
V
OUT (V)
COUT (μF)
22x2
L (μH)
22
8
5
22x2
15
3.3
2.5
1.8
1.2
22x2
10
22x2
6.8
4.7
3.3
22x2
22x2
Thermal Consideration
A7320A is high efficiency Buck converter, which means it consumes very few power when converting the high
voltage to low voltage. However, when output power is very large, like 5V/2A, the output power is as high as
10W, a heat dissipation path is strongly recommended to be routed on PCB. A7320A has two different SOP8
package. For the normal SOP8, the heat is conducted out via Pin 4 (GND), so the heat dissipation route on
PCB should be connected to the Pin 4 of the chip. If PSOP8 is selected, the heat dissipation copper area
should be exposed and connected to the exposed pad underneath the chip body.
When output power is larger than 10W, the PSOP8 package is recommended.
REV1.0
- JUN 2012 RELEASED -
- 9 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
PACKAGE INFORMATION
Dimension in SOP8 (Unit: mm)
Symbol
Min
Max
A
A1
A2
b
1.350
0.100
1.250
0.380
0.170
4.800
3.800
5.800
1.750
0.250
1.650
0.510
0.250
5.000
4.000
6.200
c
D
E
E1
e
1.270(BSC)
L
0.450
0°
0.800
8°
θ
REV1.0
- JUN 2012 RELEASED -
- 10 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
Dimension in PSOP8 Package (Unit: mm)
Symbol
Min
Max
A
A1
A2
b
1.350
0.000
1.250
0.380
0.170
4.800
3.100
3.800
5.800
2.200
1.750
0.150
1.650
0.510
0.250
5.000
3.500
4.000
6.200
2.600
c
D
D1
E
E1
E2
e
1.270(BSC)
L
0.450
0°
0.800
8°
θ
REV1.0
- JUN 2012 RELEASED -
- 11 -
A7320A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
18V (30V SPIKE) 2A SYNCHRONOUS PFM/PWM BUCK CONVERTER
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.
REV1.0
- JUN 2012 RELEASED -
- 12 -
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