AP3429

AP3429/A
1.0MHZ, 2A STEP-DOWN DC-DC BUCK CONVERTER
Description
Pin Assignments
NEW PRODUCT
The AP3429/A is a 2A step-down DC-DC converter. At heavy load,
the constant frequency PWM control performs excellent stability and
transient response. No external compensation components are
required.
The AP3429/A supports a range of input voltages from 2.7V to 5.5V,
allowing the use of a single Li+/Li- polymer cell, multiple
Alkaline/NiMH cell, and other standard power sources. The output
voltage is adjustable from 0.6V to the input voltage. The AP3429/A
employs internal power switch and synchronous rectifier to minimize
external part count and realize high efficiency. During shutdown, the
input is disconnected from the output and the shutdown current is less
than 1μA. Other key features include over-temperature and short
circuit protection, and under-voltage lockout to prevent deep battery
discharge.
(Top View)
EN
1
GND
2
LX
3
Output Current: Up to 2A

Output Voltage: 0.6V to VIN

Input Voltage: 2.7V to 5.5V
MOSFETs and 100% duty cycle operation make the AP3429/A an
ideal choice for high output voltage, high current applications which
require a low dropout threshold.

Shutdown Current: <1μA

100% Duty Cycle Operation

1MHz Switching Frequency

Internal Soft Start

No External Compensation Required

Applications
5V or 3.3V Point of Load Conversion

Telecom/Networking Equipment

Set Top Boxes

Storage Equipment

Video Cards

DDR Power Supply
Notes:
4
VIN
Features


FB
TSOT25
The AP3429/A delivers 2A maximum output current while consuming
only 90μA of no-load quiescent current. Ultra-low RDS(ON) integrated
The AP3429/A is available in TSOT25 package.
5

Short Circuit Protection

AP3429: Latch Off Protection

AP3429A: Hiccup Mode Protection
Over Voltage Protection

AP3429: Latch Off Protection

AP3429A: No Latch Off Protection

Thermal Shutdown

TSOT25 package

Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)

Halogen and Antimony Free. “Green” Device (Note 3)
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"
and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
AP3429/A
Document number: DS36561 Rev. 3 - 2
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AP3429/A
Typical Applications Circuit
VIN=2.7V to 5.5V
4
VIN
NEW PRODUCT
2
GND
1
ON OFF
AP3429/A
CIN
22mF
EN
LX
3
L1 2.2mH
C1
22pF
FB
VOUT=1.8V
R1
300k
COUT
22mFx2
5
R2
150k
Pin Descriptions
Pin Number
Pin Name
Function
1
EN
Enable control input. Force this pin voltage above 1.5V enables the chip, and below 0.4V shuts
down the device.
2
GND
3
LX
The drains of the internal main and synchronous power MOSFETs.
4
VIN
Bias supply. Chip main power supply pin.
5
FB
Feedback voltage to internal error amplifier. The threshold voltage is 0.6V.
AP3429/A
Document number: DS36561 Rev. 3 - 2
Ground pin.
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AP3429/A
Functional Block Diagram
4
SLOPE COMP
5
FB
____
OSC
FREQ
SHIFT
S
Q
R
_
Q
_
EA
VIN
EN
1
PWM
+ COMP
_
VIN
IAMP
_
+
SWITCHING
LOGIC AND
BLOCKING
CIRCUIT
3
ANTISHOOT
THRU
LX
0.6V REF
SHUTDOWN
_
2
GND
OVP
120% REF
+
Function Block Diagram of AP3429
4
1M OSC
+
SLOPE COMP
5
FB
____
OSC
S
Q
R
_
Q
_
VIN
EN
1
IAMP
_
FREQ
SHIFT
PWM
+ COMP
_
VIN
+
NEW PRODUCT
+
+
1M OSC
EA
+
SWITCHING
LOGIC AND
BLOCKING
CIRCUIT
3
ANTISHOOT
THRU
LX
0.6V REF
2
SHUTDOWN
GND
Function Block Diagram of AP3429A
AP3429/A
Document number: DS36561 Rev. 3 - 2
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AP3429/A
Absolute Maximum Ratings (Note 4)
NEW PRODUCT
Symbol
Note 4:
Parameter
Rating
Unit
-0.3 to 6
V
VIN
Input Voltage
VEN
EN Pin Voltage
-0.3 to VIN+0.3
V
VLX
LX Pin Voltage
-0.3 to VIN+0.3
V
VFB
Feedback Pin Voltage
-0.3 to VIN+0.3
V
PD
Power Dissipation (on PCB, TA = +25°C)
0.4
W
θJA
Thermal Resistance (Junction to Ambient)
220
°C/W
θJC
Thermal Resistance (Junction to Case, Simulation)
130
ºC/W
TJ
Operating Junction Temperature
+150
°C
TSTG
Storage Temperature
-55 to +150
°C
VMM
ESD (Machine Model)
200
V
VHBM
ESD (Human Body Model)
2000
V
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
Symbol
Parameter
Min
Max
Unit
VIN
Input Voltage Range
2.7
5.5
V
TA
Operating Ambient Temperature
-40
+85
°C
TJ
Junction Temperature Range
-40
+125
°C
AP3429/A
Document number: DS36561 Rev. 3 - 2
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AP3429/A
Electrical Characteristics
(@VIN = 5V, VOUT = 1.8V, L = 2.2µH, CIN = 22µF, COUT = 22µF×2, TA = +25°C, unless otherwise
specified.)
NEW PRODUCT
Symbol
Parameters
Conditions
Min
Typ
Max
Unit
VIN
Input Voltage Range
–
2.7
–
5.5
V
VFB
Regulated Feedback Voltage
–
0.588
0.6
0.612
V
IFB
FB Leakage Current
VFB = 1V
–
–
0.2
μA
IQ
Quiescent Current
VFB = 0.65V
–
90
–
μA
ISD
Shutdown Current
VEN = 0V
–
0.1
1
μA
ILIM
Peak Inductor Current
–
3
–
–
A
VSCP
Short Circuit Protection Latch
Off Threshold
–
–
0.3
–
V
fOSC
Oscillator Frequency
–
–
1
–
MHz
Drain to Source On-state
Resistance
ILX = 100mA, high side
–
110
–
ILX = 100mA, low side
–
80
–
VENH
EN High Threshold
–
1.5
–
–
V
VENL
EN Low Threshold
–
–
–
0.4
V
EN Leakage Current
VIN = VEN = 5V
-1.0
–
1.0
μA
VUVLO
Input UVLO Threshold
–
–
2.4
2.7
V
VHYS
UVLO Hysteresis
–
–
0.2
–
V
Maximum Duty Cycle
–
100
–
–
%
RDSCH
Output Discharge Switch On
Resistance
–
–
50
–
Ω
TOTP
Over Temperature Protection
–
–
+160
–
°C
TOTH
OTP Hysteresis
–
–
+30
–
°C
VIOVP
VIN Over Voltage Protection
–
–
6.25
–
V
VIHSY
IOVP Hysteresis
–
–
0.25
–
V
Soft-start Time
–
–
1.8
–
ms
RDS(ON)
IEN
–
tSS
AP3429/A
Document number: DS36561 Rev. 3 - 2
mΩ
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AP3429/A
Performance Characteristics (@TA = +25°C, VIN = 5V, VOUT = 1.8V, unless otherwise specified.)
Efficiency vs. Load Current
Feedback Reference Voltage vs. Temperature
0.620
100
90
Feedback Reference Voltage (V)
0.615
80
Efficiency (%)
60
50
40
30
VIN=5V, VOUT=1.0V
VIN=5V, VOUT=1.8V
VIN=5V, VOUT=3.3V
20
10
1
10
100
0.610
0.605
0.600
0.595
0.590
0.585
0.580
-60
0
1000
-40
-20
0
20
40
60
80
100
120
140
o
Temperature ( C)
IOUT (mA)
PFET Drain-Source On-State Resistance vs. Temperature
NFET Drain-Source On-State Resistance vs. Temperature
200
120
190
110
180
NFET RDS(ON) (m)
PFET RDS(ON)(m)
170
160
150
140
130
100
90
80
70
120
60
110
100
-60
-40
-20
0
20
40
60
80
100
120
50
-60
140
-40
-20
0
40
60
80
100
120
140
o
Temperture ( C)
Inductor Current Limit vs. Temperature
Oscillation Frequency vs. Temperature
1.20
4.4
1.15
4.2
1.10
Oscillation Frequency (MHz)
4.6
4.0
3.8
3.6
3.4
3.2
3.0
1.05
1.00
0.95
0.90
0.85
0.80
0.75
2.8
2.6
-60
20
Temperture ( C)
o
Inductor Current Limit (A)
NEW PRODUCT
70
-40
-20
0
20
40
60
80
100
120
0.70
-60
140
AP3429/A
Document number: DS36561 Rev. 3 - 2
-40
-20
0
20
40
60
80
100
120
140
o
Temperature ( C)
o
Temperature ( C)
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AP3429/A
Performance Characteristics (Cont. @TA = +25°C, VIN = 5V, VOUT = 1.8V, unless otherwise specified.)
Enable Turn on Characteristic (IOUT=2A)
Enable Turn off Characteristic (IOUT=2A)
VEN
(2V/div)
NEW PRODUCT
VEN
(2V/div)
VOUT
(1V/div)
VOUT
(1V/div)
IL
(2A/div)
IL
(2A/div)
VSW
(5V/div)
VSW
(5V/div)
Time (5ms/div)
Time (5ms/div)
Short Current Protection (IOUT=2A)
SCP Recovery (IOUT=2A)
VOUT
(1V/div)
VOUT
(1V/div)
IL
(2A/div)
IL
(2A/div)
VSW
(5V/div)
VSW
(5V/div)
Time (50ms/div)
Time (50ms/div)
Load Transient (IOUT=0.1A to 2A)
VOUT_AC
(100mV/div)
Load Transient (IOUT=1A to 2A)
VOUT_AC
(100mV/div)
IOUT
(1A/div)
IOUT
(1A/div)
Time (100µs/div)
AP3429/A
Document number: DS36561 Rev. 3 - 2
Time (100µs/div)
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AP3429/A
Application Information
Typical application circuit is shown in the application circuit and for the circuit parameters setting please refers to the following descriptions.
NEW PRODUCT
Under Voltage Lockout (UVLO) Circuit
The AP3429/A provides an under voltage lockout circuit to prevent it from undefined status. When the VIN drops lower than the UVLO detector
threshold, the UVLO circuit starts to operate, VREF stops, and high-side and low-side built-in switch transistors turn “OFF”. As a result, VOUT drops
according to the COUT capacitance value and the load. When the VIN is rising higher than UVLO released voltage, the IC will restart the operation.
Over Current Protection
The AP3429/A has internal over current protection function to protect from catastrophic failures. The IC can monitor the PMOS current, if the peak
current is higher than the current limit threshold, OCP function will be triggered and enter cycle by cycle current limit mode. If VFB drops under
0.3V for example, output node shorted to GND, AP3429 will enter latch off mode. IC will turn off both power switches. It will remain latch off state
until the VIN or Enable recycled to release it. AP3429A will enter hiccup mode to protect itself, if short circuit is removed, and VFB rises over 0.3V,
the AP3429A recovers to normal operation again.
Over Voltage Protection
The AP3429 has internal output OVP circuits. When VOUT is exceeds 120% of the regulation level for more than 40µs, the power switching will be
turned off. IC enter latch off mode and will restart until VIN or Enable voltage recycled.
Over Temperature Protection
The internal thermal temperature protection circuitry of AP3429/A is provided to protect the integrated circuit in the event that the maximum
junction temperature is exceeded. When the junction temperature exceeds +160°C, it shuts down the internal control circuit and switching power
MOSFET. The AP3429/A will restart automatically under the control of soft start circuit when the junction temperature decreases to +130°C.
Input Over Voltage Protection
When input voltage of AP3429/A is near 6.25V, 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 6V, it will leave input OVP and recover the output voltage.
AP3429/A
Document number: DS36561 Rev. 3 - 2
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AP3429/A
Ordering Information
AP3429X XX XX – XX
NEW PRODUCT
Product Name
Product Version
A : AP3429A
Blank : AP3429
Package
Temperature Range
TSOT25
-40 to +85°C
Package
KT : TSOT25
Packing
RoHS/Green
TR : Tape & Reel
G1 : Green
Part Number
Marking ID
Packing
AP3429AKTTR-G1
L2E
3000/Tape & Reel
AP3429KTTR-G1
L2F
3000/Tape & Reel
Marking Information
AP3429
(Top View)
First Line: Logo and Marking ID
AP3429A
(Top View)
First Line: Logo and Marking ID
AP3429/A
Document number: DS36561 Rev. 3 - 2
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AP3429/A
Package Outline Dimensions
Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for the latest version.
(1)
Package Type: TSOT25
D
e1
01(4x)
NEW PRODUCT
E1/2
E/2
E1
c
E
Gauge Plane
0
L
L2
01(4x)
b
e
Seating Plane
A2
A1
A
Seating Plane
TSOT25
Dim
Min
Max
Typ
A
-
1.00
A1
0.01 0.10
A2
0.84 0.90
b
0.30 0.45
c
0.12 0.20
D
2.90
E
2.80
E1
1.60
e
0.95 BSC
e1
1.90 BSC
L
0.30 0.50
L2
0.25 BSC
θ
0°
8°
4°
θ1
4°
12°
All Dimensions in mm
Suggested Pad Layout
Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version.
(1)
Package Type: TSOT25
C
Dimensions Value (in mm)
C
0.950
X
0.700
Y
1.000
Y1
3.199
Y1
Y
X
AP3429/A
Document number: DS36561 Rev. 3 - 2
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AP3429/A
IMPORTANT NOTICE
NEW PRODUCT
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.
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Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings
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This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the
final and determinative format released by Diodes Incorporated.
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 © 2015, Diodes Incorporated
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AP3429/A
Document number: DS36561 Rev. 3 - 2
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