BCD AUR9713AGH 1.5mhz, 1a, step down dc-dc converter Datasheet

Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
General Description
Features
The AUR9713 is a high efficiency step-down
DC-DC voltage converter. The chip operation is
optimized using constant frequency, peak-current
mode architecture with built-in synchronous power
MOS switchers and internal compensators to reduce
external part counts. It is automatically switching
between the normal PWM mode and LDO mode to
offer improved system power efficiency covering a
wide range of loading conditions.
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The oscillator and timing capacitors are all built-in
providing an internal switching frequency of
1.5MHz that allows the use only small surface mount
inductors and capacitors for portable product
implementations. Additional features included
integrated Soft Start (SS), Under Voltage Lock OUT
(UVLO).
AUR9713
High Efficiency Buck Power Converter
Low Quiescent Current
Output Current: 1A
Adjustable Output Voltage from 1V to 3.3V
Wide Operating Voltage Range: 2.5V to 5.5V
Built-in Power Switches for Synchronous
Rectification with High Efficiency
Feedback Voltage: 600mV
1.5MHz Constant Frequency Operation
Automatic PWM/LDO Mode Switching Control
Thermal Shutdown Protection
Low Drop-out Operation at 100% Duty Cycle
No Schottky Diode Required
Applications
•
•
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The device is available in adjustable output voltage
versions ranging from 1V to 3.3V, and is able to
deliver up to 1A.
Mobile Phone, Digital Camera and MP3 Player
Headset, Radio and Other Hand-held Instrument
Post DC-DC Voltage Regulation
PDA and Notebook Computer
The AUR9713 is available in TSOT-23-5 package.
TSOT-23-5
Figure 1. Package Type of AUR9713
Mar. 2012
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
1
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Pin Configuration
H Package
(TSOT-23-5)
EN
1
GND
2
LX
3
5
FB
4
VIN
Figure 2. Pin Configuration of AUR9713 (Top View)
Pin Description
Pin Number
Pin Name
1
EN
2
GND
3
LX
This pin is the GND reference for the NMOS power stage. It
must be connected to the system ground
Connected to inductor
4
VIN
Power supply input
5
FB
Feedback voltage from the output
Mar. 2012
Function
Enable signal input, active high
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
2
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Functional Block Diagram
Figure 3. Functional Block Diagram of AUR9713
Ordering Information
AUR9713
Package
H: TSOT-23-5
G: Green
Circuit Type
A: Adjustable Output
Package
Temperature
Range
TSOT-23-5
-40 to 80°C
Part Number
AUR9713AGH
Marking ID
9713AG
Packing Type
Tape & Reel
BCD Semiconductor's Pb-free products, as designated with "G" in the part number, are RoHS compliant and
green.
Mar. 2012
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
3
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Absolute Maximum Ratings (Note 1)
Parameter
Symbol
Value
Unit
Supply Input Voltage
VIN
0 to 6.5
V
Enable Input Voltage
VEN
-0.3 to VIN+0.3
V
Output Voltage
VOUT
-0.3 to VIN+0.3
V
Power Dissipation (On PCB, TA=30°C)
PD
0.96
W
Thermal Resistance (Junction to Ambient, Simulation)
θJA
98.4
°C/W
Thermal Resistance (Junction to Case, Simulation)
θJC
35.2
°C/W
Operating Junction Temperature
TJ
160
°C
Operating Temperature
TO
-40 to 85
°C
Storage Temperature
TS
-55 to 150
°C
ESD (Human Body Model)
VHBM
2000
V
ESD (Machine Model)
VMM
200
V
Note 1: Stresses greater than those listed under “Absolute Maximum Ratings” 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 under “Recommended Operating Conditions” is not implied. Exposure to “Absolute
Maximum Ratings” for extended periods may affect device reliability.
Recommended Operating Conditions
Parameter
Symbol
Min
Max
Unit
Supply Input Voltage
VIN
2.5
5.5
V
Junction Temperature Range
TJ
-20
125
°C
Ambient Temperature Range
TA
-40
80
°C
Mar. 2012
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
4
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Electrical Characteristics
VIN=3.6V, VOUT=2.5V, VREF=0.6V, L=2.2µH, CIN=4.7µF, COUT=10µF, TA=25°C, IMAX=1A.
Parameter
Symbol
Conditions
Min Typ Max Unit
Input Voltage Range
VIN
Shutdown Current
Regulated1Feedback
Voltage
Regulated
Output
Voltage Accuracy
Peak
Inductor
Current
IOFF
VEN=0
VFB
For Adjustable Output Voltage
Oscillator Frequency
∆VOUT/VOUT
IPK
fOSC
2.5
VIN=2.5V to 5.5V;
IOUT=0 to 1A
VIN=3V, VFB=0.5V
or
VOUT=90%, Duty Cycle<35%
VIN=3.6V
0.585
5.5
V
0.1
1
µA
0.6
0.615
V
3
%
-3
1.5
1.2
1.5
A
1.8
MHz
PMOSFET RON
RON(P)
VIN=3.6V, IOUT=200mA
0.28
Ω
NMOSFET RON
RON(N)
VIN=2.5V, IOUT=200mA
0.38
Ω
µA
Quiescent Current
IQ
ILOAD=0mA, VFB=VREF+5%
100
LX Leakage Current
ILX
VIN=5V, VEN=0V, VLX=0V or
5V
0.01
Feedback Current
IFB
EN Leakage Current
EN High-level Input
Voltage
EN Low-Level Input
Voltage
Under Voltage Lock
Out
IEN
0.01
VEN_H
VIN=2.5V to 5.5V
VEN_L
VIN=2.5V to 5.5V
Hysteresis
Thermal Shutdown
Mar. 2012
TSD
Rev. 1. 1
0.1
µA
30
nA
0.1
µA
1.5
V
0.6
V
1.8
V
0.1
V
150
°C
BCD Semiconductor Manufacturing Limited
5
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Typical Performance Characteristics
Figure 4. Efficiency vs. Output Current
Figure 5. Efficiency vs. Load Current
Figure 6. Efficiency vs. Load Current
Mar. 2012
Figure 7. LDO Mode Efficiency vs. Load Current
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
6
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Typical Performance Characteristics (Continued)
Figure 9. UVLO Threshold vs. Temperature
Figure 8. Output Voltage vs. Output Current
Figure 10. Output Voltage vs. Temperature
Mar. 2012
Figure 11. Frequency vs. Temperature
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
7
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Typical Performance Characteristics (Continued)
Figure 12. Frequency vs. Input Voltage
Figure 13. Output Current Limit vs. Temperature
VOUT
200mV/div
VLX
2V/div
VEN
2V/div
Time
Figure 14. Frequency vs. Input Voltage
Mar. 2012
400ns/div
Figure 15. Waveform of VIN=4.5V, VOUT=1.5V, L=2.2µH
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
8
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Typical Performance Characteristics (Continued)
VEN
2V/div
VOUT
1V/div
VLX
2V/div
Time
200µs/div
Figure 16. Soft Start
Mar. 2012
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
9
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Application Information
deviations do not much relieve. The selection of COUT
is determined by the Effective Series Resistance
(ESR) that is required to minimize output voltage
ripple and load step transients, as well as the amount
of bulk capacitor that is necessary to ensure that the
control loop is stable. Loop stability can be also
checked by viewing the load step transient response
as described in the following section. The output
ripple, △VOUT, is determined by:
The basic AUR9713 application circuit is shown in
Figure 18, external components selection is determined
by the load current and is critical with the selection of
inductor and capacitor values.
1. Inductor Selection
For most applications, the value of inductor is chosen
based on the required ripple current with the range of
2.2µH to 4.7µH.
∆VOUT ≤ ∆I L [ ESR +
V
1
∆I L =
VOUT (1 − OUT )
f ×L
VIN
The output ripple is the highest at the maximum input
voltage since △IL increases with input voltage.
The largest ripple current occurs at the highest input
voltage. Having a small ripple current reduces the ESR
loss in the output capacitor and improves the efficiency.
The highest efficiency is realized at low operating
frequency with small ripple current. However, larger
value inductors will be required. A reasonable starting
point for ripple current setting is △IL=40%IMAX . For a
maximum ripple current stays below a specified
value, the inductor should be chosen according to the
following equation:
L =[
3. Load Transient
A switching regulator typically takes several cycles to
respond to the load current step. When a load step
occurs, VOUT immediately shifts by an amount equal
to △ILOAD×ESR, where ESR is the effective series
resistance of output capacitor. △ILOAD 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 the recovery time, VOUT
can be monitored for overshoot or ringing that would
indicate a stability problem.
VOUT
VOUT
][1 −
]
f × ∆I L ( MAX )
VIN ( MAX )
4. Output Voltage Setting
The DC current rating of the inductor should be at
least equal to the maximum output current plus half
the highest ripple current to prevent inductor core
saturation. For better efficiency, a lower
DC-resistance inductor should be selected.
The output voltage of AUR9713 can be adjusted by a
resistive divider according to the following formula:
VOUT = VREF × (1 +
2. Capacitor Selection
I RMS = I OMAX
VOUT
R1
FB
1
2
AUR9713
R2
GND
It indicates a maximum value at VIN=2VOUT, where
IRMS=IOUT/2. This simple worse-case condition is
commonly used for design because even significant
Mar. 2012
R1
R
) = 0.6V × (1 + 1 )
R2
R2
The resistive divider senses the fraction of the output
voltage as shown in Figure 17.
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 must
be used. The maximum RMS capacitor current is
given by:
[V (V − VOUT )]
× OUT IN
VIN
1
]
8 × f × COUT
Figure 17. Setting the Output Voltage
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
10
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Application Information (Continued)
5. Efficiency Considerations
a function of both PMOSFET RDS(ON) and NMOSFET
The efficiency of switching regulator is equal to the
output power divided by the input power times 100%.
It is usually useful to analyze the individual losses to
determine what is limiting efficiency and which
change could produce the largest improvement.
Efficiency can be expressed as:
RDS(ON) resistance and the duty cycle (D):
RSW = RDS (ON )P × D + RDS (ON ) N × (1 − D )
Therefore, to obtain the I2R losses, simply add RSW to
RL and multiply the result by the square of the
average output current.
Efficiency=100%-L1-L2-…..
Where L1, L2, etc. are the individual losses as a
percentage of input power.
Other losses including CIN and COUT ESR dissipative
losses and inductor core losses generally account for
less than 2 % of total additional loss.
Although all dissipative elements in the regulator
produce losses, two major sources usually account for
most of the power losses: VIN quiescent current and
I2R losses. The VIN quiescent current loss dominates
the efficiency loss at very light load currents and the
I2R loss dominates the efficiency loss at medium to
heavy load currents.
6. Thermal Characteristics
In most applications, the part does not dissipate much
heat due to its high efficiency. However, in some
conditions when the part is operating in high ambient
temperature with high RDS(ON) resistance and high
duty cycles, such as in LDO mode, the heat
dissipated may exceed the maximum junction
temperature. To avoid the part from exceeding
maximum junction temperature, the user should do
some thermal analysis. The maximum power
dissipation depends on the layout of PCB, the thermal
resistance of IC package, the rate of surrounding
airflow and the temperature difference between
junction and ambient.
5.1 The VIN quiescent current loss comprises two
parts: the DC bias current as given in the electrical
characteristics and the internal MOSFET switch gate
charge currents. The gate charge current results from
switching the gate capacitance of the internal power
MOSFET switches. Each cycle the gate is switched
from high to low, then to high again, and the packet
of charge, dQ moves from VIN to ground. The
resulting dQ/dt is the current out of VIN that is
typically larger than the internal DC bias current. In
continuous mode,
7. PCB Layout Considerations
When laying out the printed circuit board, the
following checklist should be used to optimize the
performance of AUR9713.
I GATE = f × (Q P + Q N )
Where QP and QN are the gate charge of power
PMOSFET and NMOSFET switches. Both the DC
bias current and gate charge losses are proportional to
the VIN and this effect will be more serious at higher
input voltages.
1) The power traces, including the GND trace, the LX
trace and the VIN trace should be kept direct, short
and wide.
2) Put the input capacitor as close as possible to the
VIN and GND pins.
3) The FB pin should be connected directly to the
feedback resistor divider.
4) Keep the switching node, LX, away from the
sensitive FB pin and the node should be kept small
area.
5.2 I2R losses are calculated from internal switch
resistance, RSW and external inductor resistance RL.
In continuous mode, the average output current
flowing through the inductor is chopped between
power PMOSFET switch and NMOSFET switch.
Then, the series resistance looking into the LX pin is
Mar. 2012
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
11
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Typical Application
Note 3: VOUT = V REF × (1 +
R1
) ;
R2
When R2=300kΩ to 60 kΩ, the IR2=2µA to 10µA, and R1×C1 should be in the range between 3×10-6 and 6×10-6 for
component selection.
Figure 18. Typical Application Circuit of AUR9713
Table 1. Component Guide
VOUT(V)
Mar. 2012
R1 (kΩ)
R2 (kΩ)
C1 (pF)
L1 (µH)
3.3
450
100
13
2.2
2.5
320
100
18
2.2
1.8
200
100
30
2.2
1.2
100
100
56
2.2
1.0
66
100
91
2.2
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
12
Data Sheet
1.5MHz, 1A, STEP DOWN DC-DC CONVERTER
AUR9713
Mechanical Dimensions
5°
Unit: mm(inch)
GAUGE PLANE
TSOT-23-5
4X7
°
Mar. 2012
Rev. 1. 1
BCD Semiconductor Manufacturing Limited
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