AP3405

AP3405
600mA Step-down DC/DC Converter with Synchronous Rectifier
ADVANCED INFORMATION
Description
Pin Assignments
The AP3405 is a 2.0MHz fixed frequency, current mode, PWM
synchronous buck (step-down) DC-DC converter, capable of driving a
600mA load with high efficiency, excellent line and load regulation.
The high efficiency is easily configured by using an inductor, resistors
and capacitors as the external components. Current mode control
provides fast transient response and cycle-by-cycle current limit.
(Top View)
Pin 1 Mark
The AP3405 employs complete protection to ensure system security,
including input Undervoltage Lockout, Over-Temperature Protection
and hiccup mode Short Circuit Protection.
This IC is available in U-DFN2020-8 package.
8
EN
7
FB
3
6
VIN
4
5
SW
NC
1
NC
2
AGND
PGND
EP
U-DFN2020-8 (Type E)
Features
Applications

High-Efficiency Buck Power Converter

Post DC-DC Voltage Regulation

Input Voltage Range: 2.3V to 5.5V

Mobile Phones and Wearable Devices

Output Voltage Range: 0.7V to 5.5V

Fixed 2.0MHz Oscillator Frequency

Built-in Soft-Start Time

Built-in Overcurrent Protection

Built-in Thermal Shutdown Function

Built-in UVLO Function

Hiccup Mode SCP

Output Current: 600mA

Package: U-DFN2020-8 (Type E)

Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)

Halogen and Antimony Free. “Green” Device (Note 3)
Notes:
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.
Typical Applications Circuit
L 2.2μH
VIN
6
SW
VIN
CIN
4.7μF
AP3405
8
ON/OFF
AP3405
Document number: DS38093 Rev. 1 - 2
EN
FB
AGND
PGND
VOUT 1.8V
5
7
3
R1
240KΩ
R2
120KΩ
Cff
22pF
COUT
10μF
4
1 of 9
www.diodes.com
January 2016
© Diodes Incorporated
AP3405
ADVANCED INFORMATION
Pin Descriptions
Pin Number
Pin Name
Function
1,2
NC
3
AGND
Signal Ground Pin
4
PGND
Power Ground Pin
5
SW
Power switch output pin. This pin is connected to the inductor.
6
VIN
Supply power input pin. A capacitor should be connected between VIN pin and GND - to keep the input
voltage constant.
7
FB
Feedback pin. This pin is connected to an external resistor divider to program the system output voltage.
8
EN
Control input pin. EN is a digital input that turns the regulator on or off. Drive EN high to turn the regulator
on. Drive low to turn the regulator off.
No connection
Functional Block Diagram
EN
VIN
6
8
Slope
Compensation
OCP
Comparator
Oscillator
Current
Sensing
Shutdown
Comparator
Bias
Generator
Buffer &
Dead Time
Control
Logic
Control
Logic
Soft
Start
FB
UVLO
5
SW
PWM
Comparator
7
Reverse Inductor
Current Comparator
Error
Amplifier
Bandgap
Reference
AP3405
Document number: DS38093 Rev. 1 - 2
4
PGND
Vin OVP Comparator
3
2 of 9
www.diodes.com
AGND
January 2016
© Diodes Incorporated
AP3405
Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) (Note 4)
ADVANCED INFORMATION
Symbol
Note:
Parameter
Rating
Unit
-0.3 to 6.5
V
-0.3 to VIN + 0.3
V
VIN
VIN Input Voltage
VSW
SW Pin Voltage
VEN
EN Pin Input Voltage
-0.3 to 6.5
V
VFB
VFB Pin Voltage
-0.3 to 6.5
V
ISW
SW Pin Output Current
1
A
PD
Power Dissipation (Standard Land Pattern)
640
mW
-55 to +125
°C
2,000
V
TSTG
Storage Temperature Range
VHBM
ESD (Human Body Model)
4. 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 (@TA = +25°C, unless otherwise specified.)
Symbol
Parameter
Min
Max
Unit
VIN
Input Voltage
2.3
5.5
V
TA
Operating Ambient Temperature
-40
+85
°C
AP3405
Document number: DS38093 Rev. 1 - 2
3 of 9
www.diodes.com
January 2016
© Diodes Incorporated
AP3405
Electrical Characteristics
(VIN = VEN = 3.6V (VOUT ≤ 2.6V), VIN = VEN = VOUT+1V (VOUT > 2.6V), unless otherwise specified.
Specification with standard typeface are for TA = +25°C, and those in boldface type apply over the full operating temperature range (TA = -40°C to
+85°C))
ADVANCED INFORMATION
Symbol
VIN
Parameter
Conditions
Input Voltage
Min
Typ
Max
1.0V ≤ VOUT
2.3
–
5.5
0.9V ≤ VOUT < 1.0V
2.3
–
5.25
0.7V ≤ VOUT < 0.9V
2.3
–
4.5
Unit
V
Supply Current
VIN = VEN = VFB = 3.6V
–
32
45
µA
ISTDB
Standby Current
VIN = 5.5V, VEN = 0V
–
0
5
µA
VUVLO
Input UVLO Threshold
VIN Rising
2.0
2.1
2.2
V
VHYS
Input UVLO Hysteresis
–
–
0.1
–
V
VENH
EN Active Threshold Voltage
VIN = 5.5V
1.0
–
–
V
VENL
EN Shutdown Threshold Voltage
VIN = 2.3V
–
–
0.4
V
VFB
Feedback Voltage
VIN = VEN = 3.6V
0.591
0.600
0.609
V
IFBH
FB High Input Current
VIN = VFB = 5.5V
VEN = 0V
-1
0
1
µA
IFBL
FB Low Input Current
VEN = VFB = 0V
VIN = 5.5V
-1
0
1
µA
RONH
High-Side Switch On-Resistance
VIN = 3.6V
ISW = 100mA
–
380
–
mΩ
RONL
Low-Side Switch On-Resistance
VIN = 3.6V
ISW = 100mA
–
300
–
mΩ
ILIMH
SW Current Limit
VIN = VEN = 3.6V
800
1,000
–
mA
fOSC
Oscillator Frequency
–
1.7
2.0
2.3
MHz
DMAX
Maximum Duty Cycle
–
100
–
–
%
TOTSD
Thermal Shutdown
–
–
+140
–
°C
THYS
Thermal Shutdown Hysteresis
–
–
+40
–
°C
Soft-Start Time
VIN = VEN = 3.6V
–
150
300
µs
IDD
tSS
AP3405
Document number: DS38093 Rev. 1 - 2
4 of 9
www.diodes.com
January 2016
© Diodes Incorporated
AP3405
Performance Characteristics (TA = +25°C, VIN = 3.6V, VOUT = 1.8V, unless otherwise specified.)
Efficiency vs. Output Current
Output Voltage vs. Output Current
1.815
90
1.810
80
1.805
Output Voltage (V)
Efficiency (%)
70
60
50
40
30
VOUT = 1.8V
1.800
1.795
1.790
VIN = 3.6V
1.785
20
1.780
10
0
-50
1.775
0
50
0
100 150 200 250 300 350 400 450 500 550 600 650
100
200
Supply Current vs. Input Voltage
600
0.66
46
0.64
44
Feedback Voltage (V)
Supply Current (A)
500
0.68
48
42
40
38
36
34
VOUT = 1.8V, IOUT = 0A
32
0.62
0.60
0.58
0.56
0.54
VIN = 3.6V, Test Mode
0.52
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0.50
6.0
-40
-20
0
20
Input Voltage (V)
40
60
80
100
120
140
o
Temperature ( C)
PMOS RDSON vs. Temperature
NMOS RDSON vs. Temperature
440
360
420
340
400
320
NMOS RDSON (m)
380
360
340
320
300
280
300
280
260
240
220
ISW = 100mA
ISW = 100mA
200
260
240
-60
400
Feedback Voltage vs. Temperature
50
30
2.0
300
Output Current (mA)
Output Current (mA)
PMOS RDSON (m)
ADVANCED INFORMATION
100
-40
-20
0
20
40
60
80
100
120
140
Document number: DS38093 Rev. 1 - 2
-40
-20
0
20
40
60
80
100
120
140
O
O
Temperature ( C)
Temperature ( C)
AP3405
180
-60
5 of 9
www.diodes.com
January 2016
© Diodes Incorporated
AP3405
Performance Characteristics (continued) (TA = +25°C, VIN = 3.6V, VOUT = 1.8V, unless otherwise specified.)
ADVANCED INFORMATION
Output Ripple (IOUT = 0A)
Output Ripple (IOUT = 0.6A)
VSW
2V/div
VSW
5V/div
VOUT-AC
20mV/div
VOUT-AC
20mV/div
IL
500mA/div
IL
500mA/div
Time 1µs/div
Time 1.6ms/div
Enable Turn on Characteristic
(Resistance Load, RLOAD = 3Ω)
Enable Turn off Characteristic
(Resistance Load, RLOAD = 3Ω)
VEN
2V/div
VEN
2V/div
VOUT
2V/div
VOUT
2V/div
VSW
1V/div
VSW
1V/div
Time 50µs/div
Time 50µs/div
Short Current Protection
(Resistance Load, RLOAD =3Ω)
VOUT
1V/div
SCP Recovery
(Resistance Load, RLOAD = 3Ω)
VOUT
1V/div
IL
500mA/div
IL
500mA/div
VSW
2V/div
VSW
2V/div
Time 200µs/div
Time 200µs/div
AP3405
Document number: DS38093 Rev. 1 - 2
6 of 9
www.diodes.com
January 2016
© Diodes Incorporated
AP3405
Application Information
Please refer to the Typical Applications Circuit, and to set the circuit parameters please refer to the following descriptions.
ADVANCED INFORMATION
Undervoltage Lockout (UVLO) Circuit
When the VIN drops lower than the UVLO detector threshold, the UVLO circuit starts to operate, V REF stops, and high-side switch and low-side
switch 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.
Short Circuit Protection and Recovery
When the AP3405 output node is shorted to GND, as VFB drops under 0.3V, the chip will enter hiccup mode to protect itself, when short circuit is
removed, and VFB rises over 0.4V, the AP3405 recovers to normal operation again. If the AP3405 reaches OCP threshold while short circuit, the
AP3405 will enter cycle-by-cycle current limit mode until the current under OCP threshold.
Input Overvoltage Protection
When input voltage of AP3405 is near 6.25V, the IC will enter Input-Overvoltage-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.
Over-Temperature Protection
The internal thermal temperature protection circuitry is provided to protect the integrated circuit in the event that the maximum junction
temperature is exceeded. When the junction temperature exceeds +140°C, it shuts down the internal control circuit and switching power MOSFET.
The AP3405 will restart automatically under the control of soft start circuit when the junction temperature decreases to +100°C.
Ordering Information
AP3405SHE - 7
Package
Packing
U-DFN2020-8
7 : Tape & Reel
Device
Package
Code
Packaging
AP3405SHE-7
SHE
U-DFN2020-8
7” Tape and Reel
Quantity
3,000/Tape & Reel
Part Number Suffix
-7
Marking Information
U-DFN2020-8 (Type E)
( Top View )
XX
YWX
AP3405
Document number: DS38093 Rev. 1 - 2
XX : Identification Code
Y : Year : 0~9
W : Week : A~Z : 1~26 week;
a~z : 27~52 week; z represents
52 and 53 week
X : Internal Code
Part Number
Package
Identification Code
AP3405SHE
U-DFN2020-8
2V
7 of 9
www.diodes.com
January 2016
© Diodes Incorporated
AP3405
Package Outline Dimensions (All dimensions in mm.)
Please see AP02001 at http://www.diodes.com/_files/datasheets/ap02001.pdf for the latest version.
Package Type: U-DFN2020-8 (Type E)
ADVANCED INFORMATION
(1)
A3
A1
A
Seating Plane
D
D2
D2/2
z
Pin #1 ID
E
R0
E2/2
.2
E2
00
R0
0
.12
L
e
U-DFN2020-8
(Type E)
Dim
Min
Max
Typ
A
0.50 0.60
0.56
A1
0.00
0.05
0.02
A3
0.203
b
0.20
0.30
0.25
D
1.950 2.075 2.00
D2
1.60
1.80
1.70
e
0.500 BSC
E
1.950 2.075 2.00
E2
0.80
1.00
0.90
L
0.25
0.35
0.30
z
0.125
All Dimensions in mm
b
Suggested Pad Layout
Please see AP02001 at http://www.diodes.com/_files/datasheets/ap02001.pdf for the latest version.
(1)
Package Type: U-DFN2020-8 (Type E)
X2
C
G
Dimensions
Y2
Y1
G
X1
Y
C
G
X
X1
X2
Y
Y1
Y2
Value
(in mm)
0.500
0.150
0.350
1.800
1.850
0.500
1.000
2.300
X
AP3405
Document number: DS38093 Rev. 1 - 2
8 of 9
www.diodes.com
January 2016
© Diodes Incorporated
AP3405
IMPORTANT NOTICE
ADVANCED INFORMATION
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 indemnify and
hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees 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 and markings
noted herein may also be covered by one or more United States, international or foreign trademarks.
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 © 2016, Diodes Incorporated
www.diodes.com
AP3405
Document number: DS38093 Rev. 1 - 2
9 of 9
www.diodes.com
January 2016
© Diodes Incorporated