AP31261 - Diodes Incorporated

A Product Line of
Diodes Incorporated
AP31261
GREEN MODE PWM CONTROLLER
Description
Pin Assignments
NEW PRODUCT
The AP31261 is a current mode PWM controller which is optimized
for high performance, low standby power and cost effective offline
flyback converters.
(Top View)
The PWM switching frequency at normal operation is internally fixed
(about 65kHz). In middle load, the IC will enter green mode to
improve system efficiency with the help of frequency foldback. A
minimum switching frequency (about 20kHz) is set to avoid the
audible noise. In no load or light load, the IC will enter the burst mode
to minimize standby power. Furthermore, the frequency dithering
function is built-in to reduce EMI emission.
Pin 1 Mark
Internal slope compensation allows more stable Peak-Current Mode
control over wide range of input voltage and load conditions. Internal
line compensation ensures constant output power limit over entire
universal line voltage range.
Comprehensive protection features are included, such as cycle-bycycle current limit (OCP), VCC Over Voltage Protection (VOVP),
internal OTP, Over Load Protection (OLP) and pins’ fault protection.
GND
1
6
GATE
FB
2
5
VCC
CTRL
3
4
SENSE
SOT26
Features















Very Low Start-up Current
Current Mode Control
Non-audible-noise Green-mode Control
Internal Slope Compensation
Soft Start During Startup Process
Frequency Fold Back for High Average Efficiency
Secondary Winding Short Protection with FOCP
Soft Switching for Reducing EMI
VCC Maintain Mode
Useful Pin Fault Protection:
SENSE Pin Floating
CTRL Pin Short to Ground
FB/Opto-coupler Open/Short
Comprehensive System Protection Feature:
VCC Over Voltage Protection (VOVP)
Over Load Protection (OLP)
Mini Size Package of SOT26
Pin to Pin Compatible with AP3125A/V/R/L
Totally Lead-free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Notes:
Applications




Switching AC-DC Adapter/Charger
ATX/BTX Auxiliary Power
Set-top Box (STB) Power Supply
Open Frame Switching Power Supply
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.
AP31261
Document number: DS37514 Rev. 2 - 2
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A Product Line of
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AP31261
Typical Applications Circuit
L2
+
T1
C6
R6
R4
C2
C5
R13
C7
C8
~
-
R5
~
NEW PRODUCT
R19
C4
R14
C3
NTC
R2
U1
R8
R3
VCC
GATE
R10
C1
R9
CTRL
AP31261
F1
VR1
R7
R15
SENSE
C10
C11
R11
R16
R12
AZ431
R17
C9
FB
NTC
GND
R18
~
Pin Descriptions
Pin Number
Pin Name
1
GND
2
FB
3
CTRL
4
SENSE
5
VCC
Supply voltage of driver and control circuits
6
GATE
Gate driver output
AP31261
Document number: DS37514 Rev. 2 - 2
Function
Signal ground. Current return for driver and control circuits
Feedback. Directly connected to the opto-coupler
Latch trigger if this pin voltage drops below a threshold or over another threshold, leave CTRL pin
open if this function is not needed. Connecting a NTC thermistor to GND can achieve OTP
protection
Current Sense
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AP31261
Functional Block Diagram
VCC
16V
7.6V
5
NEW PRODUCT
32V
FB
VDD
Auto
Recovery
Protection
VCC_OVP
OLP
FOCP
CTRL_H
OTP
VCC_OVP
VCC
Latch-off
Protection
CTRL_L
28V
Soft
Start
2
Internal
Bias
UVLO
6
13V
Driver
GATE
VDD
SS
D
OSC with
Frequency
Jitter
DFF
Q
CLK RB
0.3V
2R
GND
1.3V
90ms OLP
Debounce
1
VDD
250ns LEB
R
SS
CTRL_H
3V
3
CTRL
10k
PWM
1.80V
4
100mA
CTRL_L
FOCP
1V
0.6V
4.5V
SENSE
0.95V
Line
Compensation
AP31261
Document number: DS37514 Rev. 2 - 2
OCP
OTP
o
o
+150 C /+125 C
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AP31261
May 2015
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AP31261
Absolute Maximum Ratings (Note 4)
Symbol
Parameter
VCC
IO
NEW PRODUCT
VFB, VSENSE, VCTRL
Rating
Unit
Power Supply Voltage
30
V
Gate Output Current
350
mA
-0.3 to 7
V
Input Voltage to FB, SENSE, CTRL
θJA
Thermal Resistance (Junction to Ambient)
250
°C/W
PD
Power Dissipation at TA < +25°C
500
mW
TJ
Operating Junction Temperature
-40 to +150
°C
Storage Temperature Range
+150
°C
–
ESD (Human Body Model)
3000
V
–
ESD (Machine Model)
300
V
TSTG
Note 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
Symbol
VCC
Parameter
Supply Voltage
AP31261
Document number: DS37514 Rev. 2 - 2
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Min
Max
Unit
10
25
V
May 2015
© Diodes Incorporated
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Diodes Incorporated
AP31261
Electrical Characteristics
(@TA = +25°C, VCC = 16V, unless otherwise specified.)
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
–
1
10
μA
VFB=0V, CL=1nF
0.5
0.7
1
VFB=3V, CL=0nF
0.6
1.2
2.0
Supply Voltage (VCC Pin)
ISTARTUP
NEW PRODUCT
ICC
–
Startup Current
Operating Supply Current
mA
–
UVLO (on)
–
14.5
15.8
16.5
V
–
VCC Maintain
–
8.6
9.1
9.6
V
–
UVLO (off)
–
7.1
7.6
8.1
V
–
VCC OVP
–
27
28.5
30
V
–
VCC Clamp
ICC=5mA
31
34
–
V
PWM Section/Oscillator Section
–
Maximum Duty Cycle
–
70
75
80
%
–
Oscillation Frequency
–
60
65
70
kHz
–
Green Mode Frequency
–
20
–
30
kHz
–
Frequency Temperature
Stability
-20°C to +125°C
(Note 5)
–
–
5
%
–
Frequency Voltage Stability
VCC=12V to 30V
–
–
3
%
Frequency Dithering
–
±4
±6
±8
%
Maximum SENSE Voltage
VFB=4.5V
0.9
0.95
1
V
–
FOCP Voltage
–
1.5
1.7
1.9
V
–
SENSE Shorted Protection
Threshold(Note 5)
–
–
50
–
mV
–
LEB Time of SENSE
–
150
250
350
ns
–
Delay to Output (Note 5)
–
–
100
–
ns
–
Soft-start Time
–
3
5
8
ms
–
2.5
3
3.5
V/V
12
15
18
kΩ
-0.2
-0.27
-0.34
mA
–
Current Sense Section (SENSE Pin)
VCS
Feedback Input Section (FB Pin)
The Ratio of Input Voltage to
–
Current Sense Voltage
–
Input Impedance
–
–
Source Current
VFB=0V
–
Green Mode Threshold
–
–
2.1
–
V
–
Input Voltage for Zero Duty
–
1.3
1.55
1.8
V
–
Output Low Level
IO=20mA, VCC=12V
–
–
1
V
–
Output High Level
IO=20mA, VCC=12V
8
–
–
V
–
Output Clamping Voltage
–
11
13
15
V
–
Rising Time
CL=1nF, VCC=13V
–
150
250
ns
–
Falling Time
CL=1nF, VCC=13V
–
50
100
ns
Output Section (GATE Pin)
AP31261
Document number: DS37514 Rev. 2 - 2
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AP31261
Electrical Characteristics
Symbol
(Cont.) (@TA = +25°C, VCC = 16V, unless otherwise specified.)
Parameter
Conditions
Min
Typ
Max
Unit
NEW PRODUCT
Protection Section (CTRL Pin)
–
Source Current
–
90
100
110
μA
–
Internal Reference Voltage
–
–
1.9
–
V
–
Low Threshold Trigger for
Latch
–
0.94
1
1.06
V
–
High Threshold Trigger for
Latch
–
2.85
3
3.15
V
–
Pull-up Current (Note 6)
–
–
–
2
mA
Delay of Short Circuit
Protection
Delay of Hiccup Protection
(Note 5)
–
70
90
110
ms
VCC OVP
–
6
–
Cycles
–
OTP Enter (Note 5)
–
–
+150
–
°C
–
OTP Exit (Note 5)
–
–
+125
–
°C
Delay Time Section
–
–
Internal OTP Section
Notes:
5. Guaranteed by design.
6. The sourcing current of CTRL pin must be limited below 5mA. Otherwise it may cause permanent damage to the device.
AP31261
Document number: DS37514 Rev. 2 - 2
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AP31261
Performance Characteristics
18
9.0
17
8.5
Shutdown Voltage (V)
Startup Voltage (V)
Shutdown Voltage vs. Ambient Temperature
16
15
14
8.0
7.5
7.0
13
-40
-20
0
20
40
60
80
100
120
6.5
-40
140
-20
0
o
20
40
60
80
100
120
140
o
Ambient Temperature ( C)
Ambient Temperature ( C)
Startup Current vs. Ambient Temperature
Operating Current vs. Ambient Temperature
2.0
0.9
1.8
VFB=3V, CL=0
1.6
Operating Current (mA)
0.8
Startup Current (mA)
NEW PRODUCT
Startup Voltage vs. Ambient Temperature
1.4
1.2
1.0
0.8
0.6
0.4
0.7
0.6
0.2
0.0
-40
-20
0
20
40
60
80
100
120
0.5
-40
140
o
-20
0
20
40
60
80
100
120
140
o
Ambient Temperature ( C)
Ambient Tempture ( C)
CTRL Utilization for Latch
VCC
VCC
CTRL
CTRL
NTC
OVP and OTP
AP31261
Document number: DS37514 Rev. 2 - 2
VCC
NTC
CTRL
NTC
OVP
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OTP
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AP31261
Operation Description
The AP31261 is specifically designed for off-line AC-DC power supply used in LCD monitor, notebook adapter and battery charger applications. It
offers a cost effective solution with a versatile protection function.
Start-up Current and UVLO
NEW PRODUCT
The start-up current of AP31261 is optimized to realize ultra low current (1mA typical) so that VCC capacitor can be charged more quickly. The
direct benefit of low start-up current is the availability of using large start-up resistor, which minimizes the resistor power loss for high voltage AC
input.
An UVLO comparator is included in AP31261 to detect the voltage on VCC pin. It ensures that AP31261 can draw adequate energy from hold-up
capacitor during power-on. The turn-on threshold is 16V and the turn-off threshold is 7.6V.
Current Sense Comparator and PWM Latch
The AP31261 operates as a current mode controller, the output switch conduction is initiated by every oscillator cycle and is terminated when the
peak inductor current reaches the threshold level established by the FB pin. The inductor current signal is converted to a voltage signal by
inserting a reference sense resistor RS. The inductor current under normal operating conditions is controlled by the voltage at FB pin. The relation
between peak inductor current (IPK) and VFB is:
I PK  (VFB  0.8) / 3RS
Moreover, FOCP with 1.8V threshold is only about 100ns delay, which can avoid some catastrophic damages such as secondary rectifier short
test. Few drive cycles can alleviate the destruction range and get better protection.
Leading-edge Blanking
A narrow spike on the leading edge of the current waveform can usually be observed when the power MOSFET is turned on. A 250ns leadingedge blank is built-in to prevent the false-triggering caused by the turn-on spike. During this period, the current limit comparator is disabled and
the gate driver can not be switched off.
At the time of turning off the MOSFET, a negative undershoot (maybe larger than -0.3V) can occur on the SENSE pin. So it is strongly
recommended to add a small RC filter or at least connect a resistor “R” on this pin to protect the IC (Shown as Figure 1).
5
VCC
3 CTRL
GATE 6
AP31261
1 GND
Necessary
R
SENSE 4
FB
2
C
Large undershoot (more than
-0.3V) may damage the SENSE pin
Figure 1
Built-in Slope Compensation
It is well known that a continuous current mode SMPS may become unstable when the duty cycle exceeds 50%. The built-in slope compensation
can improve the stability, so there is no need for design engineer to spend much time on that.
FB Pin and Short Circuit Protection
This pin is normally connected to the opto-coupler and always paralleled with a capacitor for loop compensation. When the voltage at this pin is
greater than 4.5V and lasts for about 90ms, the IC will enter the protection mode. For AP31261, the system will enter hiccup mode to wait the V CC
decreasing to low UVLO level, then the IC will try to restart until the failure removed. And when this voltage is less than 1.55V, the IC will stop the
drive pulse immediately. Therefore, this feature can be used for short circuit protection, which makes the system immune from damage. Normally,
output short makes the VFB value to the maximum because the opto-coupler is cut off.
AP31261
Document number: DS37514 Rev. 2 - 2
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AP31261
Operation Description (Cont.)
VCC Maintain Mode
NEW PRODUCT
During light load or step load, VFB will drop and be lower than 1.55V, thus the PWM drive signal will be stopped, and there is no more new energy
transferred due to no switching. Therefore, the IC supply voltage may reduce to the shutdown threshold voltage and system may enter the
unexpected restart mode. To avoid this, the AP31261 holds a so-called VCC maintain mode which can supply energy to VCC.
When VCC decreases to a setting threshold, the VCC maintain comparator will output some drive signal to make the system switch and provide a
proper energy to VCC pin. The VCC maintain function will cooperate with the PWM and burst mode loop which can make the output voltage
variation be within the regulation. This mode is very useful for reducing startup resistor loss and achieving a better standby performance with a low
value VCC capacitor. The VCC is not easy to touch the shutdown threshold during the startup process and step load. This will also simplify the
system design. The minimum VCC voltage is suggested to be designed a little higher than V CC maintain threshold thus can achieve the best
balance between the standby and step load performance.
System Protection and Pin Fault Protection
The AP31261 provides versatile system and pin fault protections. The OCP comparator realizes the cycle-by-cycle current limiting (OCP). In
universal input line voltage, the IC realizes the constant over load protection (OLP). VCC over voltage protection can be applied as the primary
OVP or opto-coupler broken protection. The AP31261 also has pin fault connection protection including floating and short connection. The floating
pin protection includes the SENSE, FB, etc. The short pin protection includes the CTRL pin short protection. When these pins are floated or CTRL
pin is shorted to ground, PWM switching will be disabled, thus protecting the power system.
Latch Protection Function
For some applications, the system requires the latch protection function. The CTRL pin has two kinds of modes to trigger the latch protection: high
level trigger and low level trigger. The low threshold is 1V and high threshold voltage is 3V. Some version will have only one mode. Once the latch
protection is triggered, the IC will disable the output signal, and the bulk capacitor provides the energy to IC through the startup resistor to ensure
the IC disable the output (latch mode). This mode will be not released until the AC input is shut off. So, the de-latch time is mainly depending on
the HV startup bulk capacitor value. Therefore, if the system wants a short de-latch time, it is better for the startup resistor take power from the
point before the rectifier bridge as illustrated in Figure 2.
Internal OTP Protection Function
The AP31261 integrates an internal temperature sensor. It has a trigger window of +150°C enter and +125°C exit. The internal OTP protection
mode is auto-recovery mode.
AC Mains
(90V to 265V)
CBUS
5
3
VCC
GATE
CTRL
6
AP31261
2
FB
SENSE
4
GND
1
Figure 2
AP31261
Document number: DS37514 Rev. 2 - 2
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AP31261
Ordering Information
AP31261 X XX - XX
NEW PRODUCT
Product Name
Package
Package
Packing
RoHS/Green
K : SOT26
TR : Tape & Reel
G1 : Green
Part Number
SOT26
AP31261KTR-G1
Marking ID
Packing
GPE
3000/Tape & Reel
Protection Functions
Product Name
Frequency
VOVP
OLP & SOCP
CTRL (Low)
CTRL (High)
AP31261
65kHz
Latch
Auto-Recoverable
Latch
Latch
Marking Information
(Top View)
: Logo
XXX: Marking ID (See Ordering Information)
AP31261
Document number: DS37514 Rev. 2 - 2
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AP31261
Package Outline Dimensions (All dimensions in mm(inch).)
(1)
Package Type: SOT26
0°
2.820(0.111)
8°
3.100(0.122)
2.650(0.104)
3.000(0.118)
6
0.200(0.008)
5
4
2
3
0.300(0.012)
0.600(0.024)
1.500(0.059)
1.700(0.067)
NEW PRODUCT
0.300(0.012)
0.500(0.020)
Pin 1 Mark
1
0.700(0.028)REF
0.950(0.037)TYP
0.000(0.000)
0.150(0.006)
1.800(0.071)
2.000(0.079)
0.100(0.004)
0.200(0.008)
0.900(0.035) 1.450(0.057)
MAX
1.300(0.051)
AP31261
Document number: DS37514 Rev. 2 - 2
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AP31261
Suggested Pad Layout
(1)
Package Type: SOT26
NEW PRODUCT
E
E
Y
G
Z
X
Dimensions
Z
(mm)/(inch)
G
(mm)/(inch)
X
(mm)/(inch)
Y
(mm)/(inch)
E
(mm)/(inch)
Value
3.600/0.142
1.600/0.063
0.700/0.028
1.000/0.039
0.950/0.037
AP31261
Document number: DS37514 Rev. 2 - 2
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AP31261
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).
NEW PRODUCT
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.
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AP31261
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