A7220AM8R [AITSEMI]
DC-DC CONVERTER/ BUCK (STEP-DOWN) SYNCHRONOUS BUCK CONVERTER;
| 型号： | A7220AM8R |
| 厂家： | 
AiT Semiconductor |
| 描述： | DC-DC CONVERTER/ BUCK (STEP-DOWN) SYNCHRONOUS BUCK CONVERTER DC-DC转换器 |
| 文件： | 总10页 (文件大小：434K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
DESCRIPTION
FEATURES
The A7220A is a high efficiency current-mode
synchronous, 20V/2A buck converter. Its input
voltage ranges from 4.5V to 20V and it provides an
adjustable regulated output voltage from 0.923V to
17V 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 20V
Standby current: 60uA (typ.)
Operating current at zero load: 0.1mA (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
350KHz.
Load regulation: 10mV (typ.)
High efficiency, up to 94%
Environment Temperature: -20°C~85°C
Available in SOP8 Package
A7220A consists of many protection block such as
UVLO, thermal protection and output short circuit
protection.
APPLICATION
Set-top-box
Consumer Electronic Device for automobile
LCD Monitor and LCD TV
Portable DVD
The A7220A is available in SOP8 package.
ADSL Modem, WLAN router
Other 12V or double cell Li-ion battery
powered device
ORDERING INFORMATION
Package Type
SOP8
Part Number
A7220AM8R
A7220AM8VR
TYPICAL APPLICATION
M8
V: Halogen free Package
R: Tape & Reel
Note
AiT provides all RoHS products
Suffix ꢀ V ꢀ means Halogen free Package
REV1.0
- JAN 2016 RELEASED -
- 1 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
PIN DESCRIPTION
Top View
Pin #
1
Symbol
BST
Function
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
VIN
3
4
5
6
SW
GND
FB
Power switching node to connect inductor
Ground.
Feedback input with reference voltage set to 0.923V
No Connection
NC
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.
Soft-start node. Connecting a 0.1uF capacitor to ground make the Buck
converter output rise smoothly.
7
8
EN
SS
REV1.0
- JAN 2016 RELEASED -
- 2 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
ABSOLUTE MAXIMUM RATINGS
TJ, Junction Temperature
TA, Ambient Temperature
125°C
-20°C ~ 85°C
45°C / W
θJC, Package Thermal Resistance
TS, Storage Temperature
SOP8
-40°C ~ 150°C
260°C, 10S
Lead Temperature & Time
Stress beyond above listed ꢀAbsolute Maximum Ratingsꢁ 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
Parameter
Input Voltage Range
Operating Junction Temperature
Symbol
TJ
MIN
-
MAX
20
Units
V
-20
125
°C
REV1.0
- JAN 2016 RELEASED -
- 3 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
ELECTRICAL CHARACTERISTICS
VIN=12V, TA=25°C
Parameter
Symbol
VDD
Conditions
Min.
4.5
Typ.
Max.
20
Unit
V
Input Voltage Range
UVLO,IN UVLO Rising
UVLO Threshold Hysteresis
Feedback Voltage
UVLO_UP
4.0
4.2
4.4
V
310
mV
V
VREF
IFB
VIN=12V, VEN=5V
0.900 0.923 0.946
Feedback Leakage current
0.1
60
0.4
μA
Active, VFB=1V, No Switching
Shutdown, VIN=8V
VIN=5V to 12V
μA
Quiescent Current
IQ
0.1
3
μA
Line Regulation
LnReg
LdReg
FSOC
0.1
%/V
%/A
KHz
mohm
mohm
A
Load Regulation
IOUT=0.1 to 2A
0.02
350
100
100
2.7
Switching Frequency
PMOS RDSON
VEN=2V, VIN=12V
RDSON
RDSON
ILIMIT
P
NMOS RDSON
N
Peak Current Limit
EN High Threshold
EN Low Threshold
Over Temperature Protection
VENH
VENL
TSD
1.3
V
0.5
V
150
°C
REV1.0
- JAN 2016 RELEASED -
- 4 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
TYPICAL PERFORMANCE CHARACTERISTICS
VIN=12V, VOUT=3.3V, L=10μH, CIN=10μF, COUT=22μF, TA=25°C, unless otherwise stated
1.
3.
5.
Fast Transient Response
2.
4.
6.
Startup through Enable
Shutdown through Enable
Short Circuit Recovery
Switching waveform VIN=18V, IOUT=0
Switching waveform VIN=18V, IOUT=2A
REV1.0
- JAN 2016 RELEASED -
- 5 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
7.
Switching waveform VIN=5V, IOUT=0
8.
Switching waveform VIN=5V, IOUT=2A
BLOCK DIAGRAM
REV1.0
- JAN 2016 RELEASED -
- 6 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
DETAILED INFORMATION
FUNCTIONAL DECRIPTIONS
The A7220A is a synchronous, current-mode, step-down regulator. It regulates input voltages from 4.5V to
20V down to an output voltage as low as 0.923V, and is capable of supplying up to 2A of load current.
Current-Mode Control
The A7220A utilizes current-mode control to regulate the output voltage. The output voltage is measured at
the FB pin through a resistive voltage divider and the error is amplified by the internal transconductance error
amplifier. Output of the internal error amplifier is compared with the switch current measured internally to
control the output current limit.
PFM Mode
The A7220A operates in PFM mode at light load. In PFM mode, switch frequency is continuously controlled in
proportion to the load current, i.e. switch frequency is decreased when load current drops to boost power
efficiency at light load by reducing switch-loss, while switch frequency is increased when load current rises,
minimizing both load current and output voltage ripples.
Shut-Down Mode
The A7220A operates in shut-down mode when voltage at EN pin is driven below 0.5V. In shut-down mode,
the entire regulator is off and the supply current consumed by the A7220A drops below 0.1uA.
Power Switch
N-Channel MOSFET switches are integrated on the A7220A to down convert the input voltage to the
regulated output voltage. Since the top MOSFET needs a gate voltage great than the input voltage, a boost
capacitor connected between BST and SW pins is required to drive the gate of the top switch. The boost
capacitor is charged by the internal 3.3V rail when SW is low.
VIN Under-Voltage Protection
A resistive divider can be connected between VIN and ground, with the central tap connected to EN, so that
when VIN drops to the pre-set value, EN drops below 1.1V to trigger input under voltage lockout protection.
REV1.0
- JAN 2016 RELEASED -
- 7 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
VOUT Over-Voltage Protection
When output voltage rises above its regulated value, both the top and bottom power switches are turned off.
Switching of the internal clock is also disabled. Only when output voltage falls to its regulated value can the
internal clock, top power switch, and bottom power switch become active again.
Output Current Run-Away Protection
At start-up, due to the high voltage at input and low voltage at output, current inertia of the output inductance
can be easily built up, resulting in a large start-up output current. A valley current limit is designed in the
A7220A so that only when output current drops below the valley current limit can the bottom power switch be
turned off. By such control mechanism, the output current at start-up is well controlled.
Output Short Protection
When output is shorted to ground, output current rapidly reaches its peak current limit and the top power
switch is turned off. Right after the top power switch is turned off, the bottom power switch is turned on and
stay on until the output current falls below the valley current limit. When output current is below the valley
current limit, the top power switch will be turned on again and if the output short is still present, the top power
switch is turned off when the peak current limit is reached and the bottom power switch is turned on. This
cycle goes on until the output short is removed and the regulator comes into normal operation again.
Thermal Protection
When the temperature of the A7220A rises above 150°C, it is forced into thermal shut-down. Only when core
temperature drops below 125°C can the regulator becomes active again.
Component Selectrion
When setting up the A7220A for different output voltage, please use following recommended component
value for the best performance.
VOUT (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
REV1.0
- JAN 2016 RELEASED -
- 8 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
PACKAGE INFORMATION
Dimension in SOP8 (Unit: mm)
Symbol
A
Min
Max
1.350
0.100
1.250
0.500
0.380
0.370
0.170
0.170
4.800
5.800
3.800
1.750
0.250
1.650
0.700
0.510
0.470
0.250
0.230
5.000
6.200
4.000
A1
A2
A3
b
b1
c
c1
D
E
E1
E
L
1.270(BSC)
0.450
0.800
L1
L2
R
R1
h
1.040(REF)
0.250(BSC)
0.070
0.070
0.300
-
-
0.500
e
θ
1.270(BSC)
0°
8°
θ1
θ2
θ3
θ4
15°
11°
15°
11°
19°
15°
19°
15°
REV1.0
- JAN 2016 RELEASED -
- 9 -
A7220A
DC-DC CONVERTER/ BUCK (STEP-DOWN)
20V 2A SYNCHRONOUS BUCK CONVERTER
AiT Semiconductor Inc.
www.ait-ic.com
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 servers 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
- JAN 2016 RELEASED -
- 10 -
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