A7130 [AITSEMI]
DC-DC CONVERTER/ BUCK (STEP-DOWN) SYNCHRONOUS BUCK CONVERTER;
| 型号： | A7130 |
| 厂家： | 
AiT Semiconductor |
| 描述： | DC-DC CONVERTER/ BUCK (STEP-DOWN) SYNCHRONOUS BUCK CONVERTER DC-DC转换器 |
| 文件： | 总14页 (文件大小：392K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
DESCRIPTION
FEATURES
The A7130 is a synchronous, 1.4MHz, fix frequency
PWM Buck converter. It is ideal for powering portable
equipment that powered by a single cell Lithium-ion
battery, or USB port. The A7130 can provide up to 3A
of load current with output voltage as low as 0.8V. It
can operate at 100% duty cycle for low dropout
application. With its peak current mode control and
outside compensation, the A7130 is stable with
ceramic capacitors and small inductors.
Adjustable Output Voltage, 0.8 - VIN
High efficiency, up to 96%
Output voltage accuracy 2%
0.1ohm RDSON of internal MOSFET
3A maximum output current
Up to 1.5MHz fix switching frequency
5.5V maximum operation voltage
Short circuit protection
Thermal shutdown protection
10mV Load regulation at 3A load
Compatible with ceramic output capacitor
Excellent load transient performance
In-rush current suppression
A7130 comprises a cycle-by-cycle current limit and
thermal shutdown to protect itself from fault
application.
Reverse current suppression for light load
Available in DFN10 (3X3) Packages
The A7130 is available in DFN10 (3X3) packages.
ORDERING INFORMATION
APPLICATION
3G network modem
Package Type
DFN10(3X3)
Part Number
A7130J10R
A7130J10VR
Smart phone, PDA
Digital camera
LCDTV
J10
Portable devices
R: Tape & Reel
Note
V: Halogen free Package
TYPICAL APPLICATION
AiT provides all RoHS products
Suffix ꢀ V ꢀ means Halogen free Package
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 1 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
PIN DESCRIPTION
Top View
Pin #
1
Symbol
Function
Oscillator Resistor Input. Connecting a resistor to ground from this
pin sets the switching frequency. Forcing this pin to VDD causes
the device to be shut down.
SHDN/RT
Signal Ground. All small-signal components and compensation
components should connect to this ground, which in turn connects
to PGND at one point.
2
GND
LX
Internal Power MOSFET Switches Output. Connect this pin to the
inductor.
3,4
Power Ground. Connect this pin close to the negative terminal of
5
6,7
8
PGND
PVDD
VDD
CIN and COUT
.
Power Input Supply. Decouple this pin to PGND with a capacitor.
Signal Input Supply. Decouple this pin to GND with a capacitor.
Normally VDD is equal to PVDD.
Feedback Pin. This pin Receives the feedback voltage from a
resistive divider connected across the output.
9
FB
Error Amplifier Compensation Point. The current comparator
threshold increases with this control voltage. Connect external
compensation elements to this pin to stabilize the control loop.
10
COMP
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 2 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
ABSOLUTE MAXIMUM RATINGS
VDD, PVDD, Supply Input Voltage
LX Pin Switch Voltage
-0.3V to 6V
-0.3V to (PVDD + 0.3V)
-0.3V to (VDD + 0.3V)
3.5A
Other I/O Pin Voltages
LX Pin Switch Current
Power Dissipation, PD @ TA = 25°C
θJA, Package Thermal Resistance
Junction Temperature
DFN10(3x3)
DFN10(3x3)
900mW
110°C/W
150°C
Lead Temperature (Soldering, 10 sec.)
Storage Temperature Range
ESD HBM (Human Body Mode)
260°C
-65°C to 150°C
2kV
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
Supply Input Voltage
3.6 to 5.5V
0.8V to VIN
Output Voltage Range
Junction Temperature Range
Junction Temperature Range
-40°C to 125°C
-40°C to 85°C
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 3 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
ELECTRICAL CHARACTERISTICS
VDD=5V, TA=25°C, unless otherwise specified
Parameter
Symbol
VDD(MAX)
Conditions
Min.
Typ. Max.
5.5
Unit
V
Maximum Input Voltage
VFB=0.9
500
1000
1
μA
μA
mΩ
mΩ
V
Supply Current
IIN
In Shutdown
Low side NMOS Rdson
High side PMOS Rdson
Feedback Voltage
LSON
HSON
VREF
100
100
0.8
0.1
200
220
0.816
5
0.784
-5
Feedback Leakage current
IFB
μA
Line Regulation
Load Regulation
REGLIN
VIN=4V to 5.5V
0
0.1
0.3
%/V
REGLOAD
IOUT=1 to 3A
RRT=180K
RRT=330K
0
1.44
0.03
1.8
1.15
4
0.1
%/A
MHz
MHz
A
2.16
1.44
Switching Frequency
FSOC
0.86
Peak Current Limit
Shutdown Voltage
Power on minimum VIN
voltage
ILIMIT
3.2
SHDN_V
VIN-0.7V
VIN
V
UVLO_rise Increase VIN until IC work
3.42
1.98
3.6
3.78
V
V
Power off VIN under
voltage lock out
Decrease VIN until IC shut
UVLO_fall
off
2.37
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 4 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
VDD=5V, VOUT=2.5V, TA=25°C, unless otherwise specified
1.
Efficiency VS Load Current
2.
Efficiency VS Load Current
3. Quiescent Current VS Input Voltage
4. Output Voltage VS Load Current
5.
6.
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 5 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
7.
8.
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 6 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
BLOCK DIAGRAM
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 7 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
DETAILED INFORMATION
The basic A7130 application circuit is shown in Typical Application Circuit. External component selection is
determined by the maximum load current and begins with the selection of the inductor value and operating
frequency followed by CIN and COUT
.
Output Voltage Programming
The output voltage is set by an external resistive divider according to the following equation:
VOUT =VREF×(1+R1/R2)
where VREF equals to 0.8V typical.
RT Pin Resistor Selection to set Frequency
The resistor connected between RT pin and GND is used to set the oscillation frequency of A7130.The
relation between RT resistor and frequency is shown below:
Inductor Selection
For a given input and output voltage, the inductor value and operating frequency determine the ripple current.
The ripple current IL increases with higher VIN and decreases with higher inductance.
ΔI= [VOUT/( f×L)] × [1- VOUT/VIN]
Having a lower ripple current reduces the ESR losses in the output capacitors and the output voltage ripple.
Highest efficiency operation is achieved at low frequency with small ripple current. This, however, requires a
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 8 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
large inductor. A reasonable starting point for selecting the ripple current is I = 0.4(IMAX). The largest ripple
current occurs at the highest VIN. To guarantee that the ripple current stays below a specified maximum, the
inductor value should be chosen according to the following equation:
L=[VOUT/ f ×ΔIL(MAX)] × [ 1- VOUT /VIN(MAX)
]
Inductor Core Selection
Once the value for L is known, the type of inductor must be selected. High efficiency converters generally
cannot afford the core loss found in low cost powdered iron cores, forcing the use of more expensive ferrite or
molypermalloy cores. Actual core loss is independent of core size for a fixed inductor value but it is very
dependent on the inductance selected. As the inductance increases, core losses decrease. Unfortunately,
increased inductance requires more turns of wire and therefore copper losses will increase.
Ferrite designs have very low core losses and are preferred at high switching frequencies, so design goals
can concentrate on copper loss and preventing saturation. Ferrite core material saturates ꢀhardꢁ, which
means that inductance collapses abruptly when the peak design current is exceeded.
This result in an abrupt increase in inductor ripple current and consequent output voltage ripple.
Do not allow the core to saturate!
Different core materials and shapes will change the size/ current and price/current relationship of an inductor.
Toroid or shielded pot cores in ferrite or permalloy materials are small and don't radiate energy but generally
cost more than powdered iron core inductors with similar characteristics. The choice of which style inductor to
use mainly depends on the price vs. size requirements and any radiated field/EMI requirements.
CIN and COUT Selection
The input capacitance, CIN, is needed to filter the trapezoidal current at the source of the top MOSFET.
To prevent large ripple voltage, a low ESR input capacitor sized for the maximum RMS current should be
used.
Several capacitors may also be paralleled to meet size or height requirements in the design.
The selection of COUT is determined by the effective series resistance (ESR) that is required to minimize
voltage ripple and load step transients, as well as the amount of bulk capacitance that is necessary to ensure
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 9 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
that the control loop is stable. Loop stability can be checked by viewing the load transient response as
described in a later section.
Multiple capacitors placed in parallel may be needed to meet the ESR and RMS current handling
requirements. Dry tantalum, special polymer, aluminum electrolytic and ceramic capacitors are all available in
surface mount packages. Special polymer capacitors offer very low ESR but have lower capacitance density
than other types. Tantalum capacitors have the highest capacitance density but it is important to only use
types that have been surge tested for use in switching power supplies. Aluminum electrolytic capacitors have
significantly higher ESR but can be used in cost-sensitive applications provided that consideration is given to
ripple current ratings and long term reliability. Ceramic capacitors have excellent low ESR characteristics but
can have a high voltage coefficient and audible piezoelectric effects. The high Q of ceramic capacitors with
trace inductance can also lead to significant ringing.
Using Ceramic Input and Output Capacitors
Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high
ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. However,
care must be taken when these capacitors are used at the input and output. When a ceramic capacitor is used
at the input and the power is supplied by a wall adapter through long wires, a load step at the output can
induce ringing at the input, VIN. At best, this ringing can couple to the output and be mistaken as loop
instability. At worst, a sudden inrush of current through the long wires can potentially cause a voltage spike at
VIN large enough to damage the part.
Checking Transient Response
The regulator loop response can be checked by looking at the load transient response. Switching regulators
take several cycles to respond to a step in load current. When a load step occurs, VOUT immediately shifts by
an amount equal to ΔILOAD(ESR), where ESR is the effective series resistance of COUT. ΔILOAD also begins to
charge or discharge COUT generating a feedback error signal used by the regulator to return VOUT to its
steady-state value. During this recovery time, VOUT can be monitored for overshoot or ringing that would
indicate a stability problem. The COMP pin external components and output capacitor shown in Typical
Application Circuit will provide adequate compensation for most applications.
Efficiency Considerations
The efficiency of a switching regulator is equal to the output power divided by the input power times 100%.
It is often useful to analyze individual losses to determine what is limiting the efficiency and which change
would produce the most improvement.
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 10 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
Efficiency can be expressed as :
Efficiency = 100% - (L1+ L2+ L3+ ...) where L1, L2, etc. are the individual losses as a percentage of input
power. Although all dissipative elements in the circuit produce losses, two main sources usually account for
most of the losses: VDD quiescent current and I2R losses.
The VDD quiescent current loss dominates the efficiency loss at very low load currents whereas the I2R loss
dominates the efficiency loss at medium to high load current. In a typical efficiency plot, the efficiency curve at
very low load currents can be misleading since the actual power lost is of no consequence.
1. The VDD quiescent current is due to two components: the DC bias current as given in the electrical
characteristics and the internal main switch and synchronous switch gate charge currents. The gate charge
current results from switching the gate capacitance of the internal power MOSFET switches. Each time the
gate is switched from high to low to high again, a packet of charge ΔQ moves from VDD to ground. The
resulting ΔQ/Δt is the current out of VDD that is typically larger than the DC bias current. In continuous mode,
IGATECHG = f(QT+QB) where QT and QB are the gate charges of the internal top and bottom switches.
Both the DC bias and gate charge losses are proportional to VDD and thus their effects will be more
pronounced at higher supply voltages.
2. I2R losses are calculated from the resistances of the internal switches, RSW and external inductor RL.
In continuous mode the average output current flowing through inductor L is ꢀchoppedꢁ between the main
switch and the synchronous switch. Thus, the series resistance looking into the LX pin is a function of both top
and bottom MOSFET RDS(ON) and the duty cycle (D) as follows :
RSW = RDS(ON)TOP x D + RDS(ON)BOT x (1"D)
The RDS(ON) for both the top and bottom MOSFETs can be obtained from the Typical Performance
Characteristics curves. Thus, to obtain I2R losses, simply add RSW to RL and multiply the result by the square
of the average output current. Other losses including CIN and COUT ESR dissipative losses and inductor core
losses generally account for less than 2% of the total loss.
Thermal Considerations
In most applications, the A7130 does not dissipate much heat due to its high efficiency. But, in applications
where it is running at high ambient temperature with low supply voltage and high duty cycles, such as in dropout,
the heat dissipated may exceed the maximum junction temperature of The temperature rise is given by:
TR = PD xθJA
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 11 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
Where PD is the power dissipated by the regulator and θJA is the thermal resistance from the junction of the
die to the ambient temperature.
The junction temperature, TJ, is given by:
TJ = TA + TR
Where TA is the ambient temperature.
As an example, consider the A7130 in dropout at an input voltage of 3.3V, a load current of 2A and an
ambient temperature of 70°C. The RDS(ON) of the P-Channel switch at 70°C is approximately 121mΩ.
Therefore, power dissipated by the part the part. If the junction temperature reaches approximately 150°C,
both power switches will be turned off and the SW node will become high impedance. To avoid the A7130
from exceeding the maximum junction temperature, the user will need to do some thermal analysis. The goal
of the thermal analysis is to determine whether the power dissipated exceeds the maximum junction
temperature of the part.
is:
PD = (ILOAD)2 (RDS(ON)) = (2A)2 (121mΩ) = 0.484W
For the DFN3x3 package, the θJA is 110°C /W. Thus the junction temperature of the regulator is:
TJ = 70°C + (0.484W) (110°C /W) = 123.24°C
Which is below the maximum junction temperature of 125°C.
Note that at higher supply voltages, the junction temperature is lower due to reduced switch resistance
(RDS(ON)).
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 12 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS BUCK CONVERTER
PACKAGE INFORMATION
Dimension in DFN10(3x3) (Unit: mm)
Symbol
Min
Max
A
A1
A3
D
0.700
0.000
0.175
2.950
2.950
2.300
1.500
0.800
0.050
0.250
3.050
3.050
2.650
1.750
E
D1
E1
k
0.200MIN.
b
0.180
0.350
0.300
0.450
e
0.500TYP.
L
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 13 -
A7130
DC-DC CONVERTER/ BUCK (STEP-DOWN)
AiT Semiconductor Inc.
www.ait-ic.com
3A 1.4MHz 5.5V SYNCHRONOUS 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.
REV2.0
- JUN 2010 RELEASED, JUL 2012 UPDATED -
- 14 -
相关型号：
A71308-4136N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 36 Circuits, 0.38μm (15μ) Gold (Au) Selective Plating, with 3.30mm (.130) PCB Locator Pegs
MOLEX
A713080004N
2.54mm (.100) Pitch C-Grid? Header, Surface Mount, Dual Row, Vertical, 4 Circuits, Tin (Sn) Plating, without PCB Locator Pegs
MOLEX
A713080008N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 8 Circuits, Tin (Sn) Plating, without PCB Locator Pegs
MOLEX
A713080010N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 10 Circuits, Tin (Sn) Plating, without PCB Locator Pegs
MOLEX
A713080016N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 16 Circuits, Tin (Sn) Plating, without PCB Locator Pegs
MOLEX
A713080020N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 20 Circuits, Tin (Sn) Plating, without PCB Locator Pegs
MOLEX
A713080114N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 14 Circuits, 0.38μm (15μ) Gold (Au) Selective Plating
MOLEX
A713080120N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 20 Circuits, 0.38μm (15μ) Gold (Au) Selective Plating
MOLEX
A713080140N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 40 Circuits, 0.38μm (15μ) Gold (Au) Selective Plating
MOLEX
A713080212N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 12 Circuits, 0.76μm (30μ) Gold (Au) Selective Plating, without PCB Locator Pegs
MOLEX
A713084012N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 12 Circuits, Tin (Sn) Plating, with 3.30mm (.130) PCB Locator Pegs
MOLEX
A713084120N
2.54mm (.100) Pitch C-Grid® Header, Surface Mount, Dual Row, Vertical, 20 Circuits, 0.38μm (15μ) Gold (Au) Selective Plating, with 3.30mm (.130) PCB Locator Pegs
MOLEX
©2020 ICPDF网 联系我们和版权申明