AP1684
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AP1684
A Product Line of
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Description
The AP1684 is a high performance AC/DC power factor corrected
LED driver controller which is driving high voltage bipolar transistor.
The device uses Pulse Frequency Modulation (PFM) technology to
regulate output current while achieving high power factor and low
THD. It operates as a boundary condition mode (BCM) buck controller
which is good for EMI.
The AP1684 provides accurate constant current (CC) regulation while
removing the opto-coupler and secondary control circuitry. It also
eliminates the need of loop compensation circuitry while maintaining
stability. It can meet the requirement of IEC6100-3-2 harmonic
standard.
The AP1684 features low start-up current, low operation current and
high voltage driving bipolar transistor. It adopts dynamic base driver
control technology and valley on switching mode to achieve high
efficiency. It also has rich protection features including over voltage,
short circuit, over temperature protection.
The AP1684 is available in SO-8 package.
Applications
LED Bulb Lamp
LED Down Light
GU10/E27
Other Non-dimmable LED Lighting
Pin Assignments
(Top View)
1
2
3
4
8
7
6
5
NC
RI
RM
CS
FB
GND
OUT
VCC
(SO-8/ M Package)
Features
Low Start-up Current
High PF and Low THD (PF > 0.9, THD < 30%)
High Efficiency up to 92%
BCM Mode
Output Current Accuracy on IC Level: ±2%
Tight LED Open Voltage
Valley-mode Switching to Minimize the Transition Loss
BJT Transistor Driver
Dynamic Base Driver Control
Open-load and Reload Detection
Internal Protections:
Under Voltage Lock Out (UVLO)
Leading-edge Blanking (LEB)
Output Short Protection
Output Open Protection
Over Temperature Protection
Low System Cost
SO-8 Package
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
T1
OUT
+
VCC
FB
OUT
CS
GND
C 3
R7
R5
R6
R4
D1
C4
R3
Q1
AC
Input
F 1
VR1
DB1
C2
L1
C1
R8
D2
R1
R2
RI
RM
R9
AP
1684
5
7
4
6
3
2
8
AC/DC, HIGH PF, HIGH EFFICIENCY LED DRIVER CONTROLLER
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
AP1684
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AP1684
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Pin Number
Pin Name
Function
1
NC
No connection 2 RI
The initial Tonp tuning resistor
3
RM
Set the operating mode
4
CS
Primary current sensing
5
FB
The feedback voltage sensing from the auxiliary winding
6
GND
Ground
7
OUT
Gate driver output
8
VCC
Supply voltage of gate driver and control circuits of the IC
Regulator &
Bias
Tons
Detector
Tons
Power_EN
Driver
FB
VCC
OUT
PFM
R
S
Q
Vref
CC_CTRL
TONP_CTRL
CS
GND
Vdd
Protection
& Latch
PRO
CS_OCP
FB_CV
FB_OVP
VCC_OVP
Logic
Set Initial Tonp
& Set the IC
Working in BCM
RM
RI
Constant Turn-on Time
Generation
5
2
3
4
6
7
8
Pin Descriptions
Functional Block Diagram
AP1684
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AP1684
A Product Line of
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Symbol
Parameter
Rating
Unit
VCC
Power Supply Voltage
-0.3 to 35
V
I
OUT
Driver Output Current
150
mA
VCS
Voltage at CS to GND
-0.3 to +7
V
VFB
FB Input Voltage
-40 to +10
V
TJ
Operating Junction Temperature
-40 to +150
°C
T
STG
Storage Temperature
-65 to +150
°C
T
LEAD
Lead Temperature (Soldering, 10 sec)
+300
°C
PD
Power Dissipation (TA = +50°C)
0.65
W
JA
Thermal Resistance (Junction to Ambient)
160
°C/W
–
ESD (Human Body Model)
2000
V
–
ESD (Charged-device Model)
±1000
V
Symbol
Parameter
Min
Max
Unit
VCC
Power Supply Voltage
7
25
V
TA
Ambient Temperature
-40
+105
°C
Absolute Maximum Ratings (@T
= +25°C, unless otherwise specified. Note 4)
A
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
AP1684
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Symbol
Parameter
Conditions
Min
Typ
Max
Unit
UVLO Section
V
TH
(ST)
Start-up Threshold
–
18
19
20
V
V
OPR
(Min)
Minimum Operating Voltage
After turn on
5.5
6.5
7.5
V
V
CC_OVP
VCC OVP Voltage
–
30
32
34
V – VCC Delatch Voltage (Note 5)
–
3 4 5
V
Standby Current Section
IST
Start-up Current
V
CC
= V
TH
(ST)-0.5V,
Before start up
– – 20
μA
ICC (OPR)
Operating Current
Static – 900
1300
μA
Drive Output Section
I
OUT
Output Current (Note 5)
V
CS_PEAK
= 1V
– – 60
mA
VOS
UVLO Saturation Voltage
V
CC
= 0 to V
CC-ON
, I
SINK
= 10mA
– – 1.1
V
Current Sense Section
V
CS_REF
Current Sense Reference
–
– 1 –
V
V
CS_CLAMP
Current Sense Reference
Clamp
–
1.2
1.4 – V
t
ONP_MIN
Minimum t
ONP
–
700 – 1000
ns
t
D(H-L)
Delay to Output (Note 5)
–
50
150
250
ns
Feedback Input Section
IFB
Feedback Pin Input Leakage
Current
V
FB
= 2V
–
–
4
μA
V
FB_CV
FB CV Threshold
–
3.8 4 4.2
V
V
FB_OVP
FB OVP Threshold
–
4.5 6 7.5
V
Output Current
–
System Output Current on Final
Test Board
–
– – ±2
%
Over Temperature Protection Section
–
Shutdown Temperature (Note 5)
–
+150 – –
°C
–
Temperature Hysteresis (Note 5)
– – +20 – °C
Electrical Characteristics (@T
= +25°C, unless otherwise specified.)
A
Note 5: These parameters, although guaranteed by design, are not 100% tested in production.
AP1684
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A Product Line of
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6 8 10 12 14 16 18 20 22 24 26 28 30
3.6
3.7
3.8
3.9
4.0
4.1
4.2
CV Threshold (V)
Supply Voltage (V)
-40 -20 0 20 40 60 80 100 120
16.8
17.2
17.6
18.0
18.4
18.8
19.2
Start-up Voltage (V)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
7.0
7.1
7.2
Minimal Operating Voltage (V)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
0.0
0.1
0.2
0.3
0.4
0.5
Start-up Current (
A)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
750
800
850
900
950
1000
Operating Current (
A)
Ambient Temperature (oC)
0 5 10 15 20 25 30
0
100
200
300
400
500
600
700
800
900
1000
Supply Current (
A)
Supply Voltage (V)
Performance Characteristics
Supply Current vs. Supply Voltage CV Threshold vs. Supply Voltage
Start-up Voltage vs. Ambient Temperature Minimal Operating Voltage vs. Ambient Temperature
Start-up Current vs. Ambient Temperature Operating Current vs. Ambient Temperature
AP1684
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-40 -20 0 20 40 60 80 100 120
3.00
3.25
3.50
3.75
4.00
4.25
4.50
CV Threshold (V)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
1.00
1.25
1.50
1.75
2.00
2.25
FB Leakage Current (
A)
Ambient Temperature (oC)
Performance Characteristics (Cont.)
CV Threshold vs. Ambient Temperature FB Leakage Current vs. Ambient Temperature
AP1684
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T1
OUT
+
VCC
FB
OUT
CS
GND
C 3
R7
R5
R6
R4
D1
C4
R3
Q1
AC
Input
F 1
VR1
DB1
C2
L1
C1
R8
D2
R1
R2
RI
RM
R9
AP
1684
5
7
4
6
3
2
8
8
1
_
_
R
V
kI
refcs
meano
meano
refcs
I
V
kR
_
_
8
min__
_
2
8)2(
fVV
VRVV
L
rmsinrefcs
oormsin
Application Information
The AP1684 is designed for single voltage application, and it features high power factor correction (PFC), low total harmonic distortion (THD), low
BOM cost and good EMI performance. The device can be widely used in non-dimmable LED application such as GU10, bulb lamps, down lamp,
etc. The AP1684 adopts constant on time control method within one AC cycle to achieve the high power factor and low THD. The control scheme
is very simple, the power factor correction effectiveness is obvious, and the constant current control is also good enough.
Design Parameters
Setting the Current Sense Resistor R8
As the AP1684 adopts constant on time control method, the current of the inductance will follow the input voltage to get a sinusoidal wave. The
current sense pin CS of the AP1684 will sense the peak current of the inductance by sensing the voltage dropped on the current sense resistor R8,
and the constant current control is realized by controlling the peak current. In buck structure, when the Vo is higher than Vin, no energy will be
transferred from input to output which is called dead zone, and considering the dead zone of buck structure, the output current can be calculated
as below:
Where,
V
is the reference of the current sense, and the typical value is 1V.
cs_ref
K is the current modification coefficient, and the value of k is approximate to be 0.7.
So, the current sense resistor R8 is determined:
Transformer Selection (T1)
The non-isolated buck circuit in Figure 1 is usually selected, and the system is operating at boundary conduction mode. The system’s operating
frequency does not keep constant, and considering the limit of the BJT’s operating frequency, the minimum switching frequency at the crest is set
as f
, and then the buck inductance value L can be got:
min
Where,
Vo is the output voltage.
V
in_rms
is the RMS value of the input voltage.
Figure 1. Typical Application Circuit
AP1684
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8_RBA
VL
BA
IL
N
me
refcs
me
pk
L
do
cc
Laux
VV
V
NN
sRt
initialon12_
10180
10
max__
10
28
25.1
1
rmsin
UR
L
R
0.1V
1µs
Valley
FB
Application Information (Cont.)
The next step is determining the transformer’s winding turns number, the worst case operation condition of transformer is at the peak voltage area
of sine waveform input voltage where the current of across the inductance is the maximum value. The transformer design should be based on the
worst case operation condition to guarantee that the transformer is not saturated. According to Ferrari's law of electromagnetic induction, the
winding turns number of the buck inductance NL is:
Where,
Ae is the core effective area.
Bm is the maximum magnetic flux density.
The auxiliary winding is power supply for VCC, the winding turns number N
aux
is:
Where,
Vcc is the power supply voltage for IC from auxiliary winding.
Vd is the voltage drop of the freewheel diode.
Setting the Initial On Time
As the AP1684 adopts constant on-time control method, the AP1684 will generate an initial on time to start a working cycle. If the initial on time is
longer than the rated on time, overshoot will happen which could damage the LED. And a good system performance does not permit overshoot, so
the appropriate initial on time should be guaranteed. And initial on time is determined by resister R1 shown in Figure 1.
According to initial on time generation mechanism, the t
To guarantee the system with no overshoot phenomenon, the resistor is selected
The system operation mode is determined by R2, to guarantee the system working at BCM mode, resistance R2 is generally selected as R2≤R1.
Valley on Control Method
The valley on function can provide low turn-on switching losses for buck converter. The voltage across the collector and emitter of the BJT is
reflected by the auxiliary winding of the buck transformer. The voltage is sensed by the FB pin.
is
on_initial
Figure 2. Valley on Control
AP1684
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VCC
FB
R
FB1
R
FB2
AP1684
AC Power Input
Output Voltage Range
Max Output Current
Low Mains Input
20V to 70V
200mA (13005)
High Mains Input
20V to 120V
200mA (13005)
Item
Description
Related Components
IO
LED current
R8
Output Current Ripple
Small current ripple is good for LED life
C4
t
on_initial
System initial on time, used to start up the system
R1
Output Open Voltage
Setting the output voltage when the LED is open
R5, R6
Line Compensation
To get a good line regulation
R7, R9
Startup Time
System startup time
R3, C3, T1
EMI
Pass EN 55022 class B with 6DB margin
L1, C1, C2
Application Information (Cont.)
According to Figure 2, when the falling edge of 0.1V is sensed by the FB pin, the AP1684 will see the t
new operating cycle. In this way we can realize valley on function.
Fault Protection
Over Voltage Protection and Output Open Protection
time is over and delay 1µs to start a
OFF
Figure 3. OVP Circuit
The output voltage is sensed by the auxiliary winding voltage of the buck transformer, the VCC pin and FB pin provide over voltage protection
function. When the output is open or large transient happens, the output voltage will exceed the rated value. When the voltage of VCC cap exceeds
V
or V
cc_ovp
a new work cycle and the VCC cap is charged again by start resistance. If the over voltage condition still exists, the system will work in hiccup
mode.
Output Short Protection
When the output is shorted, the output voltage will be clamped at 0. At this condition, VCC will drop down without auxiliary winding for power supply.
And the VCC will drop to UVLO threshold voltage, the IC will shut down and restart a new operating cycle, and the VCC is charged by startup
resistance. When the VCC is higher than V
energy stored in the VCC cap, because of no VCC supply from the auxiliary winding, the VCC will drop down to VCC UVLO threshold voltage again. If
output short condition still exists, the system will operate in hiccup mode.
Over Temperature Protection
The AP1684 has two kinds of over temperature protection processes. First, the system is operating normally, the ambient temperature is changed
to +170°C suddenly, the IC will trigger over temperature protection which leads to a latch work mode. Second, if the system starts, the over
temperature protection will be triggered when the ambient temperature is higher than +150°C. So the AP1684 can startup successfully when the
ambient temperature is less than +150°C.
Recommended Applications
The AP1684 is designed to drive BJT as the power switch, because of the BJT’s current limit, the maximum output current is limited. In buck
structure, the output voltage has some limitation because of the dead zone. The device is designed for single voltage application, so the
recommended application is given in the table below.
, the over voltage is triggered and the IC will discharge VCC. When the VCC is below the UVLO threshold voltage, the IC will start
FB_CV
voltage, the IC will output a bunch of pulse to control BJT on and off, which will consume the
cc_start
Components Selection Guide
If the system’s output spec is changed, please refer to the design sheet of the AP1684 and select the compatible system parameter. When the
system needs to be adjusted slightly, please refer to the table below and adjust the value of the related component.
AP1684
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AP1684 X XX – XX
PackingPackageProduct Name
TR : Tape & Reel
M : SO-8
G1 : Green
RoHS/Green
Package
Temperature
Range
Part Number
Marking ID
Packing
SO-8
-40°C to +105°C
AP1684MTR-G1
1684M-G1
4000/13”Tape & Reel
1684
M-G1
YWWAXX
First and Second Lines: Logo and Marking ID
Third Line: Date Code
Y: Year
WW: Work Week of Molding
A: Assembly House Code
XX: 7th and 8th Digits of Batch No.
Ordering Information
Diodes IC’s Pb-free products with "G1" suffix in the part number, are RoHS compliant and green.
Marking Information
(Top View)
AP1684
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0
°
8
°
1
°
7
°
R
0
.
1
5
0
(
0
.
0
0
6
)
R0.150(0.006)
1.000(0.039)
0.300(0.012)
0.510(0.020)
1.350(0.053)
1.750(0.069)
0.100(0.004)
0.300(0.012)
3.800(0.150)
4.000(0.157)
7
°
7
°
20:
1
D
1.270(0.050)
TYP
0.150(0.006)
0.250(0.010)
8
°
D
5.800(0.228)
6.200(0.244)
0.600(0.024)
0.725(0.029)
0.320(0.013)
8
°
0.450(0.017)
0.820(0.032)
4.700(0.185)
5.100(0.201)
Note: Eject hole, oriented hole and mold mark is optional
.
Option 1
Option 1
Option 2
0.
350
(0.014)
TYP
TYP
TYP
9
°
~
9
°
~
Package Outline Dimensions (All dimensions in mm(inch).)
(1) Package Type: SO-8
AP1684
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Grid
placement
courtyard
ZG
Y
E X
Dimensions
Z
(mm)/(inch)
G
(mm)/(inch)
X
(mm)/(inch)
Y
(mm)/(inch)
E
(mm)/(inch)
Value
6.900/0.272
3.900/0.154
0.650/0.026
1.500/0.059
1.270/0.050
Suggested Pad Layout
(1) Package Type: SO-8
AP1684
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