A7116E5VR-18 [AITSEMI]
DC-DC CONVERTER/ BUCK;
| 型号： | A7116E5VR-18 |
| 厂家： | 
AiT Semiconductor |
| 描述： | DC-DC CONVERTER/ BUCK DC-DC转换器 |
| 文件： | 总14页 (文件大小：433K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
DESCRIPTION
The A7116 is
synchronous buck regulator using a constant
frequency, current mode architecture.
FEATURES
a
high efficiency monolithic
High Efficiency: Up to 96%
1.5MHz Constant Switching Frequency
700mA Output Current at VIN=3.6V
Integrated Main switch and synchronous rectifier.
No Schottky Diode Required
The A7116 is available in an adjustable version and
fixed output voltages, such as 1.2V, 1.8V, etc.
Supply current with no load is 40uA and drops to
<1uA in shutdown. The 2.5V to 6.5V input voltage
range makes the A7116 ideally suited for single
Li-Ion, two to four AA battery-powered applications.
100% duty cycle provides low dropout operation,
extending battery life in portable systems. In power
saving mode, 40uA quiescent current is very
suitable for DSP/MCU in standby operation; and in
PWM mode, low output ripple voltage is good
enough for noise sensitive applications. The two
modes can be automatically switched according to
the load current.
2.5V to 6.5V Input Voltage Range
Output Voltage as Low as 0.6V
100% Duty Cycle in Dropout
Quiescent Current: 40µA(input < 4.2V)
Slope Compensated Current Mode Control for
Excellent Line and Load Transient Response
Short Circuit Protection
<1uA Shutdown Current
Available in SOT-25 Package
APPLICATION
Switching frequency is internally set at 1.5MHz,
allowing the use of small surface mount inductors
and capacitors. The internal synchronous switch
increases efficiency and eliminates the need for an
external Schottky diode. Low output voltages are
easily supported with the 0.6V feedback SOT
package.
Wireless and DSL Modems
PDAs
MP3 / MP4 /MPM Player
Digital Still and Video Cameras
Portable Instruments
The A7116 is available in SOT-25 Package.
TYPICAL APPLICATION CIRCUIT
ORDER INFORMATION
Package Type
SOT-25
Part Number
A7116E5R-XXZ
A7116E5VR-XXZ
E5
XX: Output Voltage
12=1.2V, 18=1.8V,33=3.3V
ADJ=Adjustable
Note
Z: Pin Type A or B
V: Halogen free Package
R: Tape & Reel
Figure 1 A7116-ADJ
AiT provides all RoHS products
Suffix “ V “ means Halogen free Package
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 1 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
PIN DESCRIPTION
Top View
Top View
Function
Pin #
Symbol
RUN
A
B
Regulator Enable control input. Drive RUN above 1.25V to turn on the part. Drive
RUN below 0.55V to turn it off. In shutdown, all functions are disabled drawing <1µA
supply current. Do not leave RUN floating.
1
3
2
3
2
5
GND
SW
Ground
Power Switch Output. It is the Switch note connection to Inductor. This pin connects
to the drains of the internal P-CH and N-CH MOSFET switches.
Supply Input Pin. Must be closely decoupled to GND, Pin 2, with a 2.2µF or greater
ceramic capacitor.
4
5
1
4
VIN
VFB (Adjustable): Feedback Input Pin. Connect FB to the center point of the external
resistor divider. The feedback threshold voltage is 0.6V.
VFB/VOUT
VOUT (Fixed Output): Output Voltage Feedback Pin. An internal resistive divider divides
the output voltage down for comparison to the internal reference voltage.
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 2 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
ABSOLUTE MAXIMUM RATINGS
Input Supply Voltage
-0.3V ~ +7V
0.3V ~ VIN +0.3V
-0.3V ~ VIN+0.3V
1000mA
RUN, VFB Voltages
SW Voltages
P-Channel Switch Source Current (DC)
N-Channel Switch Sink Current (DC)
Peak SW Sink and Source Current
Operating Temperature Range
Junction Temperature(NOTE)
Storage Temperature Range
Lead Temperature (Soldering, 10s)
1000mA
1.5A
-40°C ~ +85°C
+125°C
-65°C ~ +150°C
+300°C
Stresses above may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at
these or any other conditions beyond those indicated in the Electrical Characteristics is not implied. Exposure to absolute maximum
rating conditions for extended periods may affect device reliability.
NOTE: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula:
TJ = TA + (PD)x(220°C/W)
THERMAL RESISTANCE
Package
SOT-25
θJA
θJC
220°C/W
110°C/W
Thermal Resistance is specified with approximately 1 square of 1 oz copper
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 3 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
ELECTRICAL CHARACTERISTICS
VIN=VRUN= 3.6V, TA = 25°C, unless otherwise specified.
Parameter
Input Voltage Range
Input DC Supply Current
PWM Mode
Conditions
MIN
2.5
TYP
MAX
6.5
unit
V
VFB=0.5V or VOUT=90%
VFB=0.63V
300
40
400
50
µA
µA
µA
V
Power Saving Mode
Shutdown Mode
VFB=0V, VIN=4.2V
TA= +25°C
0.1
1.0
0.5880
0.5865
0.5820
0.6000
0.6000
0.6000
0.6120
0.6135
0.6180
±30
Regulated Feedback
Voltage
TA= 0°C ≤ TA ≤ 85°C
TA= -40°C ≤ TA ≤ 85°C
VFB = 0.65V
V
V
VFB Input Bias Current
Reference Voltage Line
Regulation
nA
VIN = 2.5V to 5.5V,
0.4
0.80
%
A7116-1.2, -40°C ≤ TA ≤ 85°C
A7116-1.8, -40°C ≤ TA ≤ 85°C
A7116-3.3, -40°C ≤ TA ≤ 85°C
VIN= 2.5V to 5.5V
1.164
1.746
3.201
1.200
1.800
3.300
1.236
1.854
3.399
V
V
V
Regulated Output Voltage
(In PWM mode)
Output Voltage Line
Regulation
0.4
0.5
0.80
%
%
A
Output Voltage Load
Regulation
VIN=3V, VFB=0.5V or VOUT=90%
Duty Cycle <35%
Peak Inductor Current
0.75
1.2
1.00
1.25
Oscillator Frequency
RDS(ON) of P-CH MOSFET
RDS(ON)of N-CH MOSFET
SW Leakage
VFB=0.6V or VOUT=100%
ISW = 300mA
1.5
0.40
0.35
±0.01
1.8
0.50
0.45
±1
MHz
Ω
ISW = -300mA
Ω
VRUN = 0V, VSW = 0V or 5V, VIN = 5V
µA
RUN Threshold Low
RUN Threshold High
RUN Leakage Current
0.55
-40°C ≤ TA ≤ 85°C
V
1.5
±0.01
±1
µA
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 4 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
TYPICAL PERFORMANCE CHARACTERISTICS
1. Efficiency vs. IOUT
2. Efficiency vs. IOUT
VOUT=1.2V, TA=25℃
VOUT=2.5V, TA=25℃
3. Efficiency vs. IOUT
4. Efficiency vs. IOUT
VOUT=1.5V, TA=25℃
VOUT=1.8V, TA=25℃
5. VOUT vs. IOUT
6. VOUT vs. VIN
VOUT=1.8V, TA=25℃
VOUT=2.5V, TA=25℃
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 5 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
7. IIN vs. VIN
IIN=0, VOUT=1.8V, TA=25℃
8. VOUT vs. VIN
IIN=0, VOUT=2.5V, TA=25℃
9. Efficiency vs. VIN
VOUT=3.3V, TA=25℃
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 6 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
BLOCK DIAGRAM
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 7 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
DETAILED INFORMATION
Operation
A7116 is a monolithic switching mode Step-Down DC-DC converter. It utilizes internal MOSFETs to achieve
high efficiency and can generate very low output voltage by using internal reference at 0.6V. It operates at a
fixed switching frequency, and uses the slope compensated current mode architecture. This Step-Down
DC-DC Converter supplies 700mA output current at VOUT = 1.8V with input voltage range from 2.5V to 6.5V.
Current Mode PWM Control
Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for
excellent load and line responses and protection of the internal main switch (P-Ch MOSFET) and
synchronous rectifier (N-CH MOSFET). During normal operation, the internal P-Ch MOSFET is turned on for
a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when
the peak inductor current is above the error voltage. The current comparator, ICOMP, limits the peak inductor
current. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on
until either the inductor current starts to reverse, as indicated by the current reversal comparator, IZERO, or the
beginning of the next clock cycle. The OVDET comparator controls output transient overshoots by turning the
main switch off and keeping it off until the fault is no longer present.
Power Saving Mode Operation
At very light loads, the A7116 automatically enters Power Saving Mode. In power saving mode at light load,
a control circuit puts most of the circuit into sleep in order to reduce quiescent current and improve efficiency
at light load. When the output voltage drops to certain threshold, the control circuit turns back on the
oscillator and the PWM control loop, boosting output backup. When an upper threshold is reached, the control
circuit again puts most of circuit into sleep, reducing quiescent current. During Power Saving Mode operation,
the converter positions the output voltage slightly higher than the nominal output voltage during PWM
operation, allowing additional headroom for voltage drop during a load transient from light to heavy load.
While the power saving mode improves light load efficiency, however, with the turning on and off, the noise or
ripple voltage is larger than that in the PWM Mode.
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 8 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
Dropout Operation
When the input voltage decreases toward the value of the output voltage, the A7116 allows the main switch to
(Note 6)
remain on for more than one switching cycle and increases the duty cycle
until it reaches 100% The
output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. At
low input supply voltage, the RDS(ON) of the P-Channel MOSFET increases, and the efficiency of the converter
decreases. Caution must be exercised to ensure the heat dissipated not to exceed the maximum junction
temperature of the IC.
Note 6: The duty cycle D of a step-down converter is defined as:
V OUT
D = TON × fOSC ×100% ≈
×100%
VIN
Where TON is the main switch on time and fOSC is the oscillator frequency (1.5MHz).
Maximum Load Current
The A7116 will operate with input supply voltage as low as 2.5V, however, the maximum load current
decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope
compensation signal reduces the peak inductor current as a function of the duty cycle to prevent
sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the
duty cycle decreases.
Layout Guidance
When laying out the PCB board, the following suggestions should be taken to ensure proper operation of the
A7116. These items are also illustrated graphically in Figure 2 & Figure 3.
1. The power traces, including the GND trace, the SW trace and the VIN trace should be kept short, direct
and wide.
2. The VFB pin should be connected directly to the feedback resistor. The resistive divider R1/R2 must be
connected between the (+) plate of Cout and ground.
3. Connect the (+) plate of C1 to the VIN pin as closely as possible. This capacitor provides the AC current
to internal power MOSFET.
4. Keep the switching node, SW, away from the sensitive VFB node.
5. Keep the (-) plates of C1 and C3 as close as possible.
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 9 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
LAYOUT & APPLICATION SUGGESTION
Figure 2. A7116-ADJA
Figure 3. A7116-XXA
Adjustable Output Suggested Layout
Fixed output Suggested Layout
A7116 has fixed output version. The 1.2V, 1.8V and 3.3V are the available choices. The fixed output version
can exclude the feedback resistance and capacitance.
Figure 4. Circuit of Output Version
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 10 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
Setting the Output Voltage
Figure 1 above shows the basic application circuit with A7116 adjustable output version. The external
resistor sets the output voltage according to the following equation:
R2
R1
VOUT = 0.6V × 1+
R1= 200kΩ for all outputs; R2= 200kΩ for VOUT=1.2V, R2=300kΩ for VOUT =1.5V, R2=400kΩ for VOUT =1.8V,
and R2=900kΩ for VOUT =3.3V.
Inductor Selection
For most designs, the A7116 operates with inductors of 1µH to 4.7µH. Low inductance values are physically
smaller but require faster switching, which results in some efficiency loss. The inductor value can be derived
from the following equation:
VOUT
×
(
VIN −VOUT
)
L =
VIN × ∆IL × fOSC
Where ∆IL is inductor Ripple Current. Large value inductors lower ripple current and small value inductors
result in high ripple currents. Choose inductor ripple current approximately 35% of the maximum load current
700mA, or ∆IL =245mA.
For output voltages above 2.0V, when light-load efficiency is important, the minimum recommended inductor
is 2.2µH. For optimum voltage-positioning load transients, choose an inductor with DC series resistance in the
50mΩ to 150mΩ range. For higher efficiency at heavy loads (above 200mA), or minimal load regulation (but
some transient overshoot), the resistance should be kept below 100mΩ. The DC current rating of the
inductor should be at least equal to the maximum load current plus half the ripple current to prevent core
saturation (600mA+105mA). Table 1 lists some typical surface mount inductors that meet target applications
for the A7116.
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 11 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
Size
Max DCR Rated D.C.
W x L x H
Part #
L (µH)
(mΩ)
Current (A)
(mm)
1.4
2.2
3.3
4.7
1.5
2.2
3.3
4.7
1.5
2.2
3.3
4.7
56.2
2.52
1.75
1.44
1.15
Sumida
CR43
71.2
86.2
4.5x4.0x3.5
108.7
Sumida
75
1.32
1.04
0.84
1.29
1.14
0.98
0.79
4.7x4.7x2.0
3.6x3.6x1.2
CDRH4D18
110
162
120
140
180
240
Toko
D312C
Table 1. Typical Surface Mount Inductors
Input Capacitor Selection
The input capacitor reduces the surge current drawn from the input and switching noise from the device.
The input capacitor impedance at the switching frequency shall be less than input source impedance to
prevent high frequency switching current passing to the input. A low ESR input capacitor sized for maximum
RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended
because of their low ESR and small temperature coefficients. A 4.7µF ceramic capacitor for most
applications is sufficient.
Output Capacitor Selection
The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability.
The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or
X7R dielectrics are recommended due to their low ESR and high ripple current. The output ripple VOUT is
determined by:
VOUT × (VIN −VOUT
VIN × fOSC × L
)
1
∆VOUT
≤
× ESR +
8× fosc ×C3
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 12 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
PACKAGE INFORMATION
Dimension in SOT-25 (Unit: mm)
Symbol
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
c
D
E
E1
e
0.950(BSC)
e1
L
1.800
0.300
0°
2.000
0.600
8°
θ
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 13 -
A7116
AiT Semiconductor Inc.
www.ait-ic.com
DC-DC CONVERTER/ BUCK (STEP-DOWN)
1.5MHz, 700mA SYNCHRONOUS WITH LOW QUIESCENT CURRENT
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
In order to
involve potential risks of death, personal injury, or servere property, or environmental damage.
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.
REV1.2
- JAN 2009 RELEASED, MAY 2016 UPDATED -
- 14 -
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