AP5100 [DIODES]
1.2A Step-Down Converter with 1.4MHz Switching Frequency; 1.2A降压转换器具有1.4MHz的开关频率
| 型号： | AP5100 |
| 厂家： | 
DIODES INCORPORATED |
| 描述： | 1.2A Step-Down Converter with 1.4MHz Switching Frequency |
| 文件： | 总12页 (文件大小：412K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
General Description
Features
The AP5100 is a current mode step-down converter with a built-in
power MOSFET to enable smallest solution size power
conversion.
•
•
•
•
•
•
•
•
•
•
•
VIN 4.75V to 24V
Load current of up to 1.2A
Internal Power MOSFET
Stable with Low ESR Ceramic Output Capacitors
Up to 90% Efficiency
0.1µA Shutdown Mode
Fixed 1.4MHz Frequency
Thermal Shutdown
Cycle-by-Cycle Over Current Protection
Resistor divider adjustable Output: 0.81V to 15V
SOT26: Available in “Green” Molding Compound
(no Br, Sb)
With the low series resistance power switch it enables a constant
output current of up to 1.2A over a wide input supply range. The
load and line regulation has excellent response time over the
operating input voltage and temperature range.
The AP5100 is self protected, through a cycle-by-cycle current
limiting algorithm and an on chip thermal protection.
The AP5100 will provide the voltage conversion with a low count
of widely available standard external components.
•
Lead Free Finish/RoHS Compliant (Note 1)
The AP5100 is available in SOT26 package.
Applications
•
•
•
•
Distributed Power Systems
Battery Charger
Pre-Regulator for Linear Regulators
WLED Drivers
Typical Applications
5
1
IN
V
IN
BST
SW
C1
C3
.L1
6
VOUT
AP5100
GND
D1
R1
R2
C6
ON
4
3
EN
FB
C2
OFF
Figure 1. Typical Application Circuit
AP5100
1 of 12
MARCH 2010
Document number: DS32130 Rev. 1 - 2
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© Diodes Incorporated
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Typical Applications (Continued)
5
1
VIN
IN
BST
C3
L1
C1
10µF
25V
22nF
3.3µH
VOUT
3.3V
6
3
R3
100kohm
SW
AP5100
D1
R1
C6
B230A
49.9kohm
100pF
C2
4
EN GND FB
OFF ON
22µF
6.3V
R2
16.2kohm
Figure 2. 1.4MHz, 3.3V Output at 1A Step-Down Converter
5
1
IN
BST
VIN
C3
10nF
L1
10µH
6V -12V
C1
10µF
D1
6
R3
AP5100 SW
C2
10µF
16V
25V 100Kohm
1N5819HW-7
LED1
LED 2
LED 3
- Vout
- Vout
4
3
ON
EN GND FB
OFF
R2
R4
40 ohm
1%
200Kohm
1%
- Vout
- Vout
Figure 3. White LED Driver Application
AP5100
2 of 12
MARCH 2010
Document number: DS32130 Rev. 1 - 2
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© Diodes Incorporated
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Ordering Information
AP5100 W G - 7
Green
G : Green
Packing
Package
W : SOT26
7 : Tape & Reel
Device
7” Tape and Reel
Package
Code
Packaging
(Note 2)
SOT26
Quantity
3000/Tape & Reel
Part Number Suffix
AP5100WG-7
W
-7
Notes:
1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html.
2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at
http://www.diodes.com/datasheets/ap02001.pdf.
Pin Assignments
( Top View )
1
SW
6
5
BST
2
3
IN
GND
FB
4
EN
SOT26
AP5100
3 of 12
MARCH 2010
Document number: DS32130 Rev. 1 - 2
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© Diodes Incorporated
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Pin Descriptions
Pin Name Pin #
Description
Bootstrap. To form a boost circuit, a capacitor is connected between SW and BST
pins to form a floating supply across the power switch driver. This capacitor is needed
to drive the power switch’s gate above the supply voltage. Typical values for CBST
range from 0.1uF to 1uF.
BST
1
Ground. This pin is the voltage reference for the regulated output voltage. All control
circuits are referenced to this pin. For this reason care must be taken in its layout.
Feedback. To set the output voltage, connect this pin to the output resistor divider or
directly to VOUT. To prevent current limit run away during a current limit condition, the
frequency foldback comparator lowers the oscillator frequency when the FB voltage is
below 400mV.
GND
FB
2
3
On/Off Control Input. Do not leave this pin floating. To turn the device ON, pull EN
above 1.2V and to turn it off pull below 0.4V.
If enable/disable is not used, connect a 100kOhm resistor between EN to VIN.
Supply Voltage. The AP5100 operates from a +4.75V to +24V unregulated input. A
decoupling capacitor C1 is required to prevent large voltage spikes from appearing at
the input. Place this capacitor near the IC.
EN
IN
4
5
6
SW
Switch Output. This is the reference for the floating top gate driver.
Absolute Maximum Ratings (Note 3)
Symbol
Description
Rating
Unit
ESD HBM
ESD MM
VIN
Human Body Model ESD Protection
Machine Model ESD Protection
Supply Voltage
3
300
26
KV
V
V
Switch Voltage
V
VSW
-0.3 to VIN + 0.3
VBST
Boost Voltage
V
VSW + 6
All Other Pins
–0.3 to +6
-65 to +150
+150
V
°C
TST
TJ
Storage Temperature
Junction Temperature
°C
TL
Lead Temperature
+260
°C
θJA
θJC
Junction to Ambient Thermal Resistance (Note 4)
Junction to Case Thermal Resistance (Note 4)
140
°C/W
°C/W
35
Notes:
3. Exceeding these ratings may damage the device.
4. Test condition for SOT26: Measured on approximately 1” square of 1 oz copper.
AP5100
4 of 12
MARCH 2010
Document number: DS32130 Rev. 1 - 2
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© Diodes Incorporated
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Recommended Operating Ratings (Note 5)
Symbol
Description
Rating
Unit
VIN
TA
Supply Voltage
4.75 to 24
-25 to +85
0.81 to 15
°C
°C
V
Operating Ambient Temperature Range
Output Voltage
VOUT
Notes:
5. The device function is not guaranteed outside of the recommended operating conditions.
Electrical Characteristics ( VIN = 12V, TA = +25°C, unless otherwise noted)
Symbol
Parameter
Feedback Voltage
Test Conditions
Min
Typ.
Max
Unit
VFB
IFB
RDS(ON)
4.75V ≤ VIN ≤ 24V
0.790
0.810
0.1
0.830
V
µA
Ω
µA
A
MHz
kHz
%
Feedback Current
VFB = 0.8V
Switch-On Resistance (Note 6)
Switch Leakage
Current Limit (Note 6)
Oscillator Frequency
Fold-back Frequency
Maximum Duty Cycle
0.35
V
EN = 0V, VSW = 0V
10
2.4
1.4
480
87
fSW
V
V
V
FB = 0.6V
FB = 0V
FB = 0.6V
1.1
1.7
tON
Minimum On-Time (Note 6)
Under Voltage Lockout Threshold
Rising
Under Voltage Lockout Threshold
Hysteresis
EN Input Low Voltage
EN Input High Voltage
100
ns
3.8
1.2
4.0
4.2
0.4
V
150
mV
V
V
V
EN = 2V
0.3
0.1
0.1
0.4
140
EN Input Current
µA
VEN = 0V
EN = 0V
IS
IQ
Supply Current (Shutdown)
Supply Current (Quiescent)
Thermal Shutdown (Note 6)
V
1.0
1.0
µA
mA
°C
VEN = 2V, VFB = 1V
Notes:
6. Guaranteed by design.
AP5100
5 of 12
MARCH 2010
Document number: DS32130 Rev. 1 - 2
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© Diodes Incorporated
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Typical Performance Characteristics
VIN=12V, VOUT =3.3V, L=3.3uH, C1=10uF, C2=22uF, TA=+25•C, unless otherwise noted.
Steady State Test
(IOUT=0.5A)
Load Transient Test
(IOUT=0.2A to 0.8A. Step at 0.8A/us)
Time- 100us/div
Time- 1us/div
Start-up Through Enable
(No Load)
Start-up through Enable
(IOUT=1A, resistive load)
Time- 50us/div
Time- 50us/div
Shutdown Through Enable
(No Load)
Shutdown Through Enable
(IOUT=1A, resistive load)
Time- 50us/div
Time- 50us/div
AP5100
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Document number: DS32130 Rev. 1 - 2
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AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Typical Performance Characteristics (Continued)
Short Circuit Entry
Short Circuit Recovery
Time- 100us/div
Time- 50us/div
AP5100
7 of 12
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Document number: DS32130 Rev. 1 - 2
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AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Application Information
OPERATION
at half the switching frequency, Ramp slope
The AP5100 is a current mode control, asynchronous
buck regulator. Current mode control assures excellent
line and load regulation and a wide loop bandwidth for
fast response to load transients. Figure. 4 depicts the
functional block diagram of AP5100.
compensation is utilized. This will help to stabilize the
power supply. This Ramp compensation is summed to
the Current Sense Amplifier output and compared to the
Error Amplifier output by the PWM Comparator. When
the sum of the Current Sense Amplifier output and the
Slope Compensation signal exceeds the EA output
voltage, the RS Flip-Flop is reset and HS MOSFET is
turned off. The external Schottky rectifier diode (D1)
conducts the inductor current.
The operation of one switching cycle can be explained as
follows. At the beginning of each cycle, HS (high-side)
MOSFET is off. The EA output voltage is higher than the
current sense amplifier output, and the current
comparator’s output is low. The rising edge of the
1.4MHz oscillator clock signal sets the RS Flip-Flop. Its
output turns on HS MOSFET.
For one whole cycle, if the sum of the Current Sense
Amplifier output and the Slope Compensation signal
does not exceed the EA output, then the falling edge of
the oscillator clock resets the Flip-Flop. The output of the
Error Amplifier increases when feedback voltage (VFB)
is lower than the reference voltage of 0.81V. This also
increases the inductor current as it is proportional to the
EA voltage.
When the HS MOSFET is on, inductor current starts to
increase. The Current Sense Amplifier senses and
amplifies the inductor current. Since the current mode
control is subject to sub-harmonic oscillations that peak
Figure 4. Functional Block Diagram
AP5100
Document number: DS32130 Rev. 1 - 2
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AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Application Information (Continued)
Setting the Output Voltage
Peak current determines the required saturation current
rating, which influences the size of the inductor.
Saturating the inductor decreases the converter
efficiency while increasing the temperatures of the
inductor, the MOSFET and the diode. Hence choosing
an inductor with appropriate saturation current rating is
important.
The output voltage can be adjusted from 0.81V to 15V
using an external resistor divider. Table 1 shows a list of
resistor selection for common output voltages. Resistor
R1 is selected based on a design tradeoff between
efficiency and output voltage accuracy. For high values
of R1 there is less current consumption in the feedback
network. However the trade off is output voltage
accuracy due to the bias current in the error amplifier. R2
can be determined by the following equation:
A 1µH to 10µH inductor with a DC current rating of at
least 25% percent higher than the maximum load current
is recommended for most applications.
For highest efficiency, the inductor’s DC resistance
should be less than 200mΩ. Use a larger inductance
for improved efficiency under light load conditions.
V
⎛
⎞
OUT
⎜
⎜
⎟
R
= R
×
2
− 1
1
⎟
⎠
0.81
⎝
VOUT (V)
R1 (kΩ)
R2 (kΩ)
Input Capacitor
The input capacitor reduces the surge current drawn
from the input supply and the switching noise from the
device. The input capacitor has to sustain the ripple
current produced during the on time on the upper
MOSFET. It must hence have a low ESR to minimize the
losses.
1.8
2.5
3.3
5
80.6 (1%)
49.9 (1%)
49.9 (1%)
49.9 (1%)
64.9 (1%)
23.7 (1%)
16.2 (1%)
9.53 (1%)
Due to large dI/dt through the input capacitors,
electrolytic or ceramics should be used. If a tantalum
must be used, it must be surge protected. Otherwise,
capacitor failure could occur. For most applications, a
4.7µF ceramic capacitor is sufficient.
Table 1. Resistor Selection for Common
Output Voltages
Inductor
Calculating the inductor value is a critical factor in
designing a buck converter. For most designs, the
following equation can be used to calculate the inductor
value;
Output Capacitor
The output capacitor keeps the output voltage ripple
small, ensures feedback loop stability and reduces the
overshoot of the output voltage. The output capacitor is a
basic component for the fast response of the power
supply. In fact, during load transient, for the first few
microseconds it supplies the current to the load. The
converter recognizes the load transient and sets the duty
cycle to maximum, but the current slope is limited by the
inductor value.
V
× (V − V
)
OUT
V
IN
IN
OUT
L =
× ΔI × f
SW
L
Where ΔI is the inductor ripple current.
L
And f
SW
is the buck converter switching frequency.
Maximum capacitance required can be calculated from
the following equation:
Choose the inductor ripple current to be 30% of the
maximum load current. The maximum inductor peak
current is calculated from:
ΔI
L
I
= I +
L(MAX) LOAD
2
AP5100
Document number: DS32130 Rev. 1 - 2
9 of 12
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MARCH 2010
© Diodes Incorporated
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Application Information (Continued)
ΔI
External Bootstrap Diode
inductor 2
)
L(I
+
OUT
It is recommended that an external bootstrap diode be
added when the input voltage is no greater than 5V or the
5V rail is available in the system. This helps improve the
efficiency of the regulator. The bootstrap diode can be a
low cost one such as IN4148 or BAT54.
2
2
C
=
o
2
(Δ V + V
OUT
)
− V
OUT
Where ΔV is the maximum output voltage overshoot.
ESR of the output capacitor dominates the output
voltage ripple. The amount of ripple can be calculated
from the equation below:
5V
BOOST
DIODE
1
Vout
= ΔI
× ESR
inductor
capacitor
BST
10nF
An output capacitor with ample capacitance and low
ESR is the best option. For most applications, a 22µF
ceramic capacitor will be sufficient.
AP5100
6
SW
External Diode
Figure 5. External Bootstrap Diode
The external diode’s forward current must not exceed the
maximum output current. Since power dissipation is a
critical factor when choosing a diode, it can be calculated
from the equation below:
V
OUT
P
diode
= (1−
)×I
× 0.3V
out
V
IN
Note: 0.3V is the voltage drop across the schottky diode.
A diode that can withstand this power dissipation must
be chosen.
PC Board Layout
This is a high switching frequency converter. Hence
attention must be paid to the switching currents
interference in the layout. Switching current from one
power device to another can generate voltage transients
across the impedances of the interconnecting bond wires
and circuit traces. These interconnecting impedances
should be minimized by using wide, short printed circuit
traces. The input capacitor needs to be as close as
possible to the IN and GND pins. The external feedback
resistors should be placed next to the FB pin.
AP5100
Document number: DS32130 Rev. 1 - 2
10 of 12
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© Diodes Incorporated
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
Marking Information
(1) SOT26
( Top View )
6
5
4
XX : Identification Code
Y : Year 0~9
XX Y W X
W : Week : A~Z : 1~26 week;
a~z : 27~52 week; z represents
52 and 53 week
1
2
3
X : A~Z : Green
Part Number
Package
Identification Code
AP5100W
SOT26
AJ
Package Information (All Dimensions in mm)
(1) Package type: SOT26
AP5100 Rev. 1
11 of 12
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Document number: DS32130 Rev. 1 - 2
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© Diodes Incorporated
AP5100
1.2A Step-Down Converter with 1.4MHz Switching
Frequency
IMPORTANT NOTICE
DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS
DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).
Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other
changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability
arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any
license under its patent or trademark rights, nor the rights of others. Any Customer or user of this document or products described
herein in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies
whose products are represented on Diodes Incorporated website, harmless against all damages.
Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized
sales channel.
Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall
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arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application.
Products described herein may be covered by one or more United States, international or foreign patents pending. Product names
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LIFE SUPPORT
Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without
the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
A. Life support devices or systems are devices or systems which:
1. are intended to implant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided
in the labeling can be reasonably expected to result in significant injury to the user.
B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected
to cause the failure of the life support device or to affect its safety or effectiveness.
Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or
systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements
concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems,
notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further,
Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes
Incorporated products in such safety-critical, life support devices or systems.
Copyright © 2010, Diodes Incorporated
www.diodes.com
AP5100 Rev. 1
12 of 12
MARCH 2010
Document number: DS32130 Rev. 1 - 2
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© Diodes Incorporated
相关型号：
AP5100SG-13
Features: • VIN 4.75V to 24V • Load current of up to 1.2A • Internal Power MOSFET • Stable with Low ESR Ceramic Output Capacitors • Up to 90% Efficiency • 0.1μA Shutdown Mode • Fixed 1.4MHz Frequency • Thermal Shutdown • Cycle-by-Cycle Over Current Protection • Resistor divider adjustable Output: 0.81V to 15V • SOT26: Available in “Green” Molding Compound Applications: • Distributed Power Systems • Battery Charger • Pre-Regulator for Linear Regulators • WLED Drivers
DIODES
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