AP3435MPTR-G1 [DIODES]
Switching Regulator, Current-mode, 4.5A, 1000kHz Switching Freq-Max, PDSO8, SOP-8;
| 型号： | AP3435MPTR-G1 |
| 厂家： | 
DIODES INCORPORATED |
| 描述： | Switching Regulator, Current-mode, 4.5A, 1000kHz Switching Freq-Max, PDSO8, SOP-8 CD 开关 光电二极管 输出元件 |
| 文件： | 总17页 (文件大小：541K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
Features
General Description
•
•
•
•
•
•
High Efficiency Buck Power Converter
Output Current: 3.5A
The AP3435 is a high efficiency step-down DC-DC
voltage converter. The chip operation is optimized
by peak-current mode architecture with built-in
synchronous power MOS switchers. The oscillator
and timing capacitors are all built-in providing an
internal switching frequency of 1MHz that allows
the use of small surface mount inductors and
capacitors for portable product implementations.
Low RDS(ON) Internal Switches:100mΩ (VIN=5V)
Adjustable Output Voltage from 0.8V to 0.9×VIN
Wide Operating Voltage Range: 2.7V to 5.5V
Built-in Power Switches for Synchronous
Rectification with High Efficiency
Feedback Voltage: 800mV
1.0MHz Constant Frequency Operation
Thermal Shutdown Protection
•
•
•
•
•
•
Integrated Soft Start (SS), Under Voltage Lock Out
(UVLO), Thermal Shutdown Detection (TSD) and
Short Circuit Protection are designed to provide
reliable product applications.
Low Drop-out Operation at 100% Duty Cycle
No Schottky Diode Required
Input Over Voltage Protection
The device is available in adjustable output voltage
versions ranging from 0.8V to 0.9×VIN
(2.7V≤VIN≤5.5V), and is able to deliver up to 3.5A.
Applications
•
•
•
•
LCD TV
Set Top Box
Post DC-DC Voltage Regulation
PDA and Notebook Computer
The AP3435 is available in PSOP-8 package.
PSOP-8
Figure 1. Package Type of AP3435
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
1
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
Pin Configuration
MP Package
(PSOP-8)
8
1
2
3
4
7
6
5
Figure 2. Pin Configuration of AP3435 (Top View)
Pin Description
Pin Number
Pin Name
Function
1
2
3
VCC
NC
Supply input for the analog circuit
No connection
GND
Ground pin
Feedback pin. Receive the feedback voltage from a
resistive divider connected across the output
4
5
FB
EN
Chip enable pin. Active high, internal pull-high with
200kΩ resistor
6
7
8
PGND
SW
Power switch ground pin
Switch output pin
VIN
Power supply input for the MOSFET switch
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
2
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
AP3435
Functional Block Diagram
EN
VIN
VCC
5
1
8
Saw-Tooth
Generator
Over-Current
Comparator
Oscillator
Current
Sensing
Bias
Generator
+
Buffer &
Dead Time
Control
Soft
Start
7
SW
4
Control
Logic
_
+
_
Logic
FB
+
Modulator
Error
Amplifier
_
+
_
Reverse Inductor
Current Comparator
+
Over Voltage
Comparator
Bandgap
Reference
3
6
GND
PGND
Figure 3. Functional Block Diagram of AP3435
Ordering Information
AP3435
-
G1: Green
TR: Tape & Reel
Circuit Type
Package
MP: PSOP-8
Temperature
Package
Range
Part Number
AP3435MPTR-G1
Marking ID
Packing Type
PSOP-8
-40 to 80°C
3435MP-G1
Tape & Reel
BCD Semiconductor's Pb-free products, as designated with "G1" in the part number, are RoHS compliant and
green.
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
3
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
AP3435
Absolute Maximum Ratings (Note 1)
Parameter
Symbol
VCC
Value
0 to 6.0
0 to 6.0
-0.3 to VIN+0.3
-0.3 to VIN+0.3
4.5
Unit
V
Supply Input for the Analog Circuit
Power Supply Input for the MOSFET Switch
SW Pin Switch Voltage
VIN
V
VSW
V
Enable Input Voltage
VEN
V
SW Pin Switch Current
ISW
A
Power Dissipation (on PCB, TA=25°C)
Thermal Resistance (Junction to Ambient, Simulation)
Operating Junction Temperature
Operating Temperature
PD
θJA
2.47
W
°C/W
°C
40.43
TJ
160
TOP
TSTG
VHBM
VMM
°C
-40 to 85
-55 to 150
2000
Storage Temperature
°C
ESD (Human Body Model)
ESD (Machine Model)
V
V
200
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
VIN
Min
2.7
Max
5.5
Unit
V
Supply Input Voltage
Junction Temperature Range
Ambient Temperature Range
TJ
-40
125
80
°C
TA
-40
°C
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
4
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
Electrical Characteristics
VIN=VCC=VEN=5V, VOUT=1.2V, VFB=0.8V, L=2.2μH, CIN=10μF, COUT=22μF, TA=25°C, unless otherwise
specified.
Parameter
Symbol
Conditions
Min Typ Max Unit
Input
Range
Voltage
VIN
2.7
5.5
1
V
Shutdown Current
Active Current
IOFF
ION
VEN=0
μA
μA
VFB=0.95V
310
0.784 0.8 0.816
Regulated Feedback
Voltage
Regulated Output
Voltage Accuracy
Peak Inductor
Current
For Adjustable Output Voltage
VFB
ΔVOUT/VOUT
IPK
V
%
VIN=2.7V to 5.5V,
IOUT=0 to 3.5A
-3
3
4.5
A
Oscillator
Frequency
fOSC
VIN=2.7V to 5.5V
1.0
MHz
PMOSFET RON
NMOSFET RON
RON(P)
RON(N)
VIN=5V
VIN=5V
100
100
mΩ
mΩ
EN High-level Input
Voltage
EN Low-level Input
Voltage
VEN_H
VEN_L
1.5
V
V
0.4
EN Input Current
Soft Start Time
IEN
tSS
1
μA
μs
400
Maximum Duty
Cycle
DMAX
100
%
Rising
2.4
2.3
0.1
Under Voltage Lock
Out Threshold
VUVLO
Falling
V
Hysteresis
Hysteresis=30°C
Thermal Shutdown
TSD
150
5.9
0.4
°C
V
Rising
5.8
0.3
6.0
0.5
Input Over Voltage
Protection (IOVP)
VIOVP
Hysteresis
V
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
5
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
AP3435
Typical Performance Characteristics
100
100
90
80
70
60
50
40
30
20
10
0
VIN=5V, VOUT=1.2V
VIN=5V, VOUT=3.3V
90
80
70
60
50
40
30
20
10
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Output Current (A)
Output Current (A)
Figure 4. Efficiency vs. Output Current
Figure 5. Efficiency vs. Output Current
1.24
3.40
3.38
3.36
3.34
3.32
3.30
3.28
3.26
3.24
3.22
3.20
VIN=5V, VOUT=1.2V
VIN=5V, VOUT=3.3V
1.23
1.22
1.21
1.20
1.19
1.18
1.17
1.16
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Output Current (A)
Output Current (A)
Figure 6. Load Regulation
Figure 7. Load Regulation
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
6
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
Typical Performance Characteristics (Continued)
AP3435
3.40
3.38
3.36
3.34
3.32
3.30
3.28
3.26
3.24
3.22
3.20
1.24
1.23
1.22
1.21
1.20
1.19
1.18
1.17
1.16
IOUT= 0
IOUT=0
IOUT= 3.5A
IOUT=3.5A
OUT=3.3V
V
OUT=1.2V
V
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Input Voltage (V)
Input Voltage (V)
Figure 8. Line Regulation
Figure 9. Line Regulation
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
VOUT= 1.2V
VOUT= 3.3V
2.5
3.0
3.5
4.0
4.5
5.0
5.5
4.0
4.5
5.0
5.5
Input Voltage (V)
Input Voltage (V)
Figure 10. Frequency vs. Input Voltage
Figure 11. Frequency vs. Input Voltage
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
7
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
Typical Performance Characteristics (Continued)
AP3435
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
H Level
L Level
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Input Voltage (V)
Input Voltage (V)
Figure 12. Enable Threshold Voltage vs. Input Voltage
Figure 13. Current Limit vs. Input Voltage
90
VOUT= 1.2V
85
80
75
70
65
60
55
50
45
40
35
30
25
VEN
2V/div
VOUT
1V/div
ISW
2A/div
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Output Current (A)
Time 400μs/div
Figure 14. Case Temperature vs. Output Current
Figure 15. Enable Waveform
(VIN=5V, VEN=0V to 5V, VOUT=3.3V, IOUT=3.5A)
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
8
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
Typical Performance Characteristics (Continued)
VIN
2V/div
VOUT
1V/div
VIN
2V/div
VOUT
1V/div
ISW
2A/div
ISW
2A/div
Time 400μs/div
Time 20ms/div
Figure 16. Power-On
Figure 17. Power-Off
(VIN=0V to 5V, VEN=VIN, VOUT=3.3V, IOUT=3.5A)
(VIN=5V to 0V, VEN=VIN, VOUT=3.3V, IOUT=3.5A)
VSW
VSW
2V/div
5V/div
VOUT
1V/div
VOUT_AC
20mV/div
IOUT
2A/div
ISW
2A/div
Time 400μs/div
Time 400ns/div
Figure 18. Short Circuit Protection
Figure 19. VOUT Ripple
(VIN=5V=VEN, VOUT=3.3V, IOUT=2A to short)
(VIN=5V=VEN, VOUT=3.3V, IOUT=0A)
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
9
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
Typical Performance Characteristics (Continued)
VSW
5V/div
VSW
5V/div
VOUT_AC
20mV/div
VOUT_AC
20mV/div
ISW
ISW
2A/div
2A/div
Time 400ns/div
Time 400ns/div
Figure 20. VOUT Ripple
Figure 21. VOUT Ripple
(VIN=5V=VEN, VOUT=3.3V, IOUT=1A)
(VIN=5V=VEN, VOUT=3.3V, IOUT=3.5A)
VOUT_AC
200mV/div
VOUT_AC
200mV/div
IOUT
IOUT
500mA/div
500mA/div
Time 100μs/div
Time 100μs/div
Figure 22. Load Transient of 1.2V Output
(VIN=5V=VEN, VOUT=1.2V, IOUT=0.5A to 2A)
Figure 23. Load Transient of 3.3V Output
(VIN=5V=VEN, VOUT=3.3V, IOUT=0.5A to 2A)
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
10
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
Typical Performance Characteristics (Continued)
VIN
1V/div
VIN
1V/div
IOUT
500mA/div
VOUT
1V/div
IOUT
500mA/div
VOUT
1V/div
Time 100μs/div
Time 100μs/div
Figure 24. OVP Function (VIN=5V to 6V)
Figure 25. Leave OVP Function (VIN=6V to 5V)
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
11
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
AP3435
Application Information
The basic AP3435 application circuit is shown in Figure
27, external components selection is determined by the
load current and is critical with the selection of inductor
and capacitor values.
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. The output ripple, △VOUT, is
determined by:
1. Inductor Selection
For most applications, the value of inductor is chosen
based on the required ripple current with the range of
1μH to 6.8μH.
1
ΔVOUT ≤ ΔIL[ESR +
]
8× f ×COUT
The output ripple is the highest at the maximum input
voltage since △IL increases with input voltage.
1
VOUT
VIN
ΔIL =
VOUT (1−
)
f × L
3. Load Transient
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:
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
L = [
][1−
]
4. Output Voltage Setting
The output voltage of AP3435 can be adjusted by a
resistive divider according to the following formula:
f ×ΔIL (MAX )
VIN (MAX )
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,
DC-resistance inductor should be selected.
R
R1
R2
VOUT = VREF ×(1+ 1 ) = 0.8V × (1+
)
R2
a
lower
The resistive divider senses the fraction of the output
voltage as shown in Figure 26.
2. Capacitor 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 must
be used. The maximum RMS capacitor current is
given by:
VOUT
R1
FB
R2
AP3435
1
[VOUT (VIN −VOUT )]2
GND
IRMS = IOMAX
×
VIN
It indicates a maximum value at VIN=2VOUT, where
RMS=IOUT/2. This simple worse-case condition is
Figure 26. Setting the Output Voltage
I
commonly used for design because even significant
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
12
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
AP3435
Application Information (Continued)
the VIN and this effect will be more serious at higher
input voltages.
5. Short Circuit Protection
When the AP3435 output node is shorted to GND, as
VFB drops under 0.4V, the chip will enter soft-start
mode to protect itself, when short circuit is removed,
and VFB rises over 0.4V, the AP3435 recovers back to
normal operation again. If the AP3435 reaches OCP
threshold while short circuit, the AP3435 will enter
soft-start cycle until the current under OCP threshold.
6.2 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 SW pin is
a function of both PMOSFET RDS(ON) and NMOSFET
6. Efficiency Considerations
RDS(ON) resistance and the duty cycle (D):
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:
RSW = RDS P × D + RDS
×
(
1− D
)
(
ON
)
(
ON N
)
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-…..
Other losses including CIN and COUT ESR dissipative
losses and inductor core losses generally account for
less than 2 % of total additional loss.
Where L1, L2, etc. are the individual losses as a
percentage of input power.
7. Thermal Characteristics
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.
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.
6.1 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,
8. Input Over Voltage Protection
When input voltage of AP3435 is near 6V, the IC
will enter Input-Over-Voltage-Protection. It would be
shut down and there will be no output voltage in this
state. As the input voltage goes down below 5.5V, it
will leave input OVP and recover the output voltage.
IGATE = f × (QP + QN )
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
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
13
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
AP3435
Application Information (Continued)
2) Put the input capacitor as close as possible to the
VIN and GND pins.
9. PCB Layout Considerations
When laying out the printed circuit board, the
following checklist should be used to optimize the
performance of AP3435.
3) The FB pin should be connected directly to the
feedback resistor divider.
1) The power traces, including the GND trace, the SW
trace and the VIN trace should be kept direct, short
and wide.
4) Keep the switching node, SW, away from the
sensitive FB pin and the node should be kept small
area.
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
14
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter AP3435
Typical Application
R
Note 2: VOUT = VREF × (1+ 1 ) .
R2
Figure 27. Typical Application Circuit of AP3435
VOUT(V)
3.3
R1 (kΩ)
31.25
21.5
12.5
5
R2 (kΩ)
10
L (μH)
2.2
2.5
10
2.2
1.8
10
2.2
1.2
10
2.2
1.0
3
10
2.2
Table 1. Component Guide
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
15
Preliminary Datasheet
1.0MHz, 3.5A, Synchronous Step Down DC-DC Converter
AP3435
Mechanical Dimensions
PSOP-8
Unit:mm(inch)
Dec. 2012 Rev. 1. 0
BCD Semiconductor Manufacturing Limited
16
BCD Semiconductor Manufacturing Limited
http://www.bcdsemi.com
- Headquarters
- Wafer Fab
BCD Semiconductor Manufacturing Limited
Shanghai SIM-BCD Semiconductor Manufacturing Co., Ltd.
No. 1600, Zi Xing Road, Shanghai ZiZhu Science-based Industrial Park, 200241, China
800 Yi Shan Road, Shanghai 200233, China
Tel: +86-21-24162266, Fax: +86-21-24162277
Tel: +86-21-6485 1491, Fax: +86-21-5450 0008
REGIONAL SALES OFFICE
Shenzhen Office
Taiwan Office
USA Office
Shanghai SIM-BCD Semiconductor Manufacturing Co., Ltd., Shenzhen Office
BCD Semiconductor (Taiwan) Company Limited
BCD Semiconductor Corp.
Unit A Room 1203, Skyworth Bldg., Gaoxin Ave.1.S., Nanshan District, Shenzhen,
4F, 298-1, Rui Guang Road, Nei-Hu District, Taipei,
30920 Huntwood Ave. Hayward,
China
Taiwan
Tel: +886-2-2656 2808
CA 94544, USA
Tel: +86-755-8826 7951
Tel : +1-510-324-2988
Fax: +86-755-8826 7865
Fax: +886-2-2656 2806
Fax: +1-510-324-2788
相关型号：
AP34M60B
Power Field-Effect Transistor, 34A I(D), 600V, 0.21ohm, 1-Element, N-Channel, Silicon, Metal-oxide Semiconductor FET, TO-247AB, ROHS COMPLIANT, 3 PIN
MICROSEMI
©2020 ICPDF网 联系我们和版权申明