AL1678-20B 10B 08B

AL1678-20B/10B/08B
UNIVERSAL, 500V BUCK LED DRIVER
Description
Pin Assignments
NEW PRODUCT
The AL1678-20B/10B/08B is a universal AC input (85 to 277 VAC),
high efficiency and high accuracy Buck LED driver. The AL167820B/10B/08B topology provides accurate constant current over line
and load regulation with tight tolerance ±3%, operating at boundary
conduction mode (BCM) to ease in EMI/EMC qualification and testing
to meet the latest regulatory laws.
(Top View)
The AL1678-20B/10B/08B single Buck stage system works with a
single winding inductor and High voltage MOSFET included,
therefore, can use fewer external components and create a low bill of
material (BOM) cost solution. The AL1678-20B/10B/08B has rich
protection features to enhance the system safety and reliability. It has
thermal fold back function, which can reduce the output current when
the driver’s temperature is higher than the setting value.
7
Drain
3
6
LC
4
5
CS
OUT
1
VCC
2
ROVP
GND
SO-7
The AL1678-20B/10B/08B is available in SO-7 package.
Applications
Features












> 90% Efficiency
Valley Switching to Achieve Low Switching Loss
Universal 85 to 277 VAC Input Range
Internal MOSFET up to 500V
Tight Current Sense Tolerance: ±3%
Low Start-up Current: 170µA
Low Operation Current: 100µA (Static)
Single Winding Inductor
Internal Protections

Under Voltage Lock Out (UVLO)

Leading-edge Blanking (LEB)

Output Open/Short Protection

Open-load and Reload Detection

Thermal Fold-back Function

Over Temperature Protection (OTP)
SO-7 Package
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Notes:



Retrofit LED Lamps
High Voltage DC-DC LED Driver
General Purpose Constant Current Source
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
R1
R4
D1
C3
+
OUT
L1
F1
AC
Input
R2
DB1
C1
R3
C2
1 OUT Drain 7
2
VCC
6
3
ROVP LC
4 GND
5
CS
U1 AL1678-20B/10B/08B
AL1678-20B/10B/08B
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AL1678-20B/10B/08B
NEW PRODUCT
Pin Descriptions
Pin Number
Pin Name
Function
1
OUT
Internal power MOSFET’s source
2
VCC
Power supply for the device
3
ROVP
4
GND
5
CS
Current sensing
6
LC
Line compensation pin
7
Drain
Setting the open voltage of the output
Ground
Internal high voltage MOSFET’s drain
Functional Block Diagram
Drain
VCC
7
2
STOP
UVLO
Fault
VCC
VCC
Clamp
Management
Management
OTP
3
1
ROVP
OUT
toff Detection
(ZCD)
VCC
OVP
Output
OVP
Q
S
R
5
CS
LEB
Constant
Current Control
Max ton
Limit
6
STOP
LC
4
GND
AL1678-20B/10B/08B
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AL1678-20B/10B/08B
Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) (Note 4)
Symbol
Rating
Unit
18
V
AL1678-20B
500
V
AL1678-10B
500
V
AL1678-08B
500
V
AL1678-20B
2.0
A
AL1678-10B
1.0
A
AL1678-08B
0.8
A
Voltage on CS Pin
-0.3 to 7
V
Voltage on ROVP Pin
-0.3 to 7
V
Operating Junction Temperature
-40 to +150
ºC
TSTG
Storage Temperature
-65 to +150
ºC
TLEAD
Lead Temperature (Soldering, 10 sec)
+260
ºC
0.65
W
Thermal Resistance (Junction to Ambient)
190
ºC/W
ESD (Human Body Model)
2000
V
ESD (Machine Model)
200
V
VCC
NEW PRODUCT
VDrain
ID
VCS
VROVP
TJ
PD
θJA
Parameter
Power Supply Voltage
Voltage on Drain Pin
Continuous Drain Current
(TC = +25oC)
Power Dissipation and Thermal Characteristics
(TA = +50oC)
–
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
TA
Note 5:
Parameter
Ambient Temperature (Note 5)
Min
Max
Unit
-40
+105
°C
The device can operate normally at +125°C ambient temperature under the condition that the junction temperature is less than +150°C.
AL1678-20B/10B/08B
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AL1678-20B/10B/08B
Electrical Characteristics
Symbol
(@TA = +25°C, unless otherwise specified.)
Parameter
Conditions
Min
Typ
Max
Unit
UVLO Section
Startup Threshold
–
–
14.5
–
V
VOPR(Min)
Minimal Operating Voltage
After Turn On
–
8.5
–
V
VCC_Clamp
VCC Clamp Voltage
–
–
16.2
–
V
–
170
–
µA
Static
–
100
–
µA
AL1678-20B
–
5.4
6
AL1678-10B
–
10
12
16
20
NEW PRODUCT
VTH (ST)
Standby Current Section
IST
ICC(OPR)
Start-up Current
Operating Current
VCC = VTH (ST)-0.5V,
Before Start Up
Internal High Voltage MOSFET
RDS(ON)
Drain-Source on State
Resistance
AL1678-08B
Ω
AL1678-20B
–
–
2.0
AL1678-10B
–
–
1.0
AL1678-08B
–
–
0.8
AL1678-20B
500
–
–
AL1678-10B
500
–
–
AL1678-08B
500
–
–
–
–
1
–
–
1
–
–
1
–
–
+140
–
Reference Voltage of ROVP
Pin
–
–
0.46
–
V
VCS-REF
Current Sense Reference
–
0.388
0.400
0.412
V
tON_MIN
Minimum tON
–
400
–
700
ns
tON_MAX
Maximum tON
–
–
35
–
µs
tOFF_MAX
Maximum tOFF
–
–
200
–
µs
tOFF_MIN
Minimum tOFF (Note 6)
–
–
6
–
µs
Delay to Output (Note 6)
–
50
150
250
ns
–
–
+170
–
°C
IDS
VDS
Continuous Drain-Source
Current
Drain-source Voltage
VDS = 500V, VGS = 0,
TC = +25oC (AL1678-20B)
IDSS
Drain-source Leakage
Current
VDS = 500V, VGS = 0,
TC = +25oC (AL1678-10B)
VDS = 500V, VGS = 0,
TC = +25oC (AL1678-08B)
A
V
µA
Thermal Foldback Section And ROVP Section
TREG
VROVP
Overheating Temperature
Regulation (Note 6)
o
C
Current Sense Section
tD(H-L)
Over Temperature Protection Section
–
Notes:
Shutdown Temperature
(Notes 6 & 7)
6. These parameters, although guaranteed by design, are not 100% tested in production.
7. The device will latch when OTP happens and the device won’t operate constantly at this temperature.
AL1678-20B/10B/08B
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AL1678-20B/10B/08B
Performance Characteristics (Note 8)
Start-up Voltage vs. Ambient Temperature
Start-up Current vs. Ambient Temperature
16.0
180
15.5
170
Start-up Current (A)
Start-up Voltage (V)
14.5
14.0
13.5
13.0
160
150
140
130
12.5
12.0
-40
-20
0
20
40
60
80
100
120
-40
120
-20
0
20
40
60
o
Ambient Temperature ( C)
100
120
Operating Current vs. Ambient Temperature
10.0
140
9.5
130
9.0
Operating Current (A)
Minimal Operating Voltage (V)
80
o
Ambient Temperature ( C)
Minimal Operating Voltage vs. Ambient Temperature
8.5
8.0
7.5
7.0
120
110
100
90
80
6.5
6.0
-40
-20
0
20
40
60
80
100
70
-40
120
-20
0
20
40
60
80
100
120
o
Ambient Temperature ( C)
o
Ambient Temperature ( C)
VCS Reference vs. Ambient Temperature
VROVP Reference vs. Ambient Temperature
0.50
0.60
0.45
0.55
0.40
0.50
VROVP Reference (V)
VCS Reference (V)
NEW PRODUCT
15.0
0.35
0.30
0.25
0.20
-40
0.45
0.40
0.35
-20
0
20
40
60
80
100
120
0.30
-40
o
AL1678-20B/10B/08B
Document number: DS37637 Rev. 1 - 2
-20
0
20
40
60
80
100
120
o
Ambient Temperature ( C)
Ambient Temperature ( C)
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AL1678-20B/10B/08B
Performance Characteristics (Note 8)
VCC Clamp Voltage vs. Ambient Temperature
VCS Reference vs. Ambient Temperature
0.50
20
0.45
0.40
0.35
VCS Reference (V)
NEW PRODUCT
VCC Clamp Voltage (V)
18
16
14
12
0.30
0.25
0.20
0.15
0.10
0.05
10
-40
-20
0
20
40
60
80
100
0.00
-40
120
-20
0
20
40
60
80
100
120
140
160
180
o
Ambient Temperature ( C)
o
Ambient Temperature ( C)
Integrated 500V/2A MOSFET SOA (Note 9)
ID, Drain Current (A)
ID, Drain Current (A)
Integrated 500V/1A MOSFET SOA (Note 9)
VDS, Drain-to-source Voltage (V)
Notes:
VDS, Drain-to-source Voltage (V)
8. These electrical characteristics are tested under DC condition. The ambient temperature is equal to the junction temperature of the device.
9. The MOSFET SOA curve is tested under the TO-251 package type.
AL1678-20B/10B/08B
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AL1678-20B/10B/08B
Application Information
The AL1678-20B/10B/08B is designed for single inductor buck application, it is an extremely low BOM cost solution widely used in non-isolate
situation. It operates as boundary conduction mode (BCM) which can get a good EMI performance. The device internally integrates a 500V high
voltage MOSFET. The AL1678-20B/10B/08B adopts a novel method to detect the tOFF time and realize an extremely low operation current, so the
device does not need the auxiliary winding for VCC supply and detects the tOFF time. It also has a good constant current control which can
NEW PRODUCT
guarantee the system current accuracy.
R1
R4
D1
C3
+
OUT
L1
F1
AC
Input
R2
DB1
C1
R3
C2
1 OUT Drain 7
2
VCC
6
3
ROVP LC
4 GND
5
CS
U1 AL1678-20B/10B/08B
R5
Figure 1. Typical Application Circuit
Design Parameters
Setting the Current Sense Resistor R5
The AL1678-20B/10B/08B uses peak current control method to obtain constant current control and senses the peak current of the inductor cycle
by cycle. The sample value is compared with the internal 0.4V reference, when the sample value is up to 0.4V, the IC control the internal MOSFET
turned off.
So the peak current of the inductance is
I peak 
VCS _ REF
R5
Where,
VCS_REF is the reference of the current sense, and the typical value is 0.4V.
R5 is the current sense resistor.
In no PF buck topology, the system operates at boundary conduct mode, so the output current is
I o _ mean 
1
 I peak
2
So, the current sense resistor R5 is determined:
R5 
1 VCS _ REF

2 I o _ mean
Inductance Selection (L1)
The AL1678-20B/10B/08B controls the system operating at boundary conduction mode, and the system’s operating frequency does not keep
constant because of the fluctuation of the bus voltage, set the minimum switching frequency fmin at the maximum bus voltage, and buck inductance
value L1 is:
AL1678-20B/10B/08B
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AL1678-20B/10B/08B
Application Information (Cont.)
L1 
( 2Vin _ rms  Vo )  R5  Vo
VCS _ REF  2Vin _ rms  f m in
Where,
NEW PRODUCT
Vo is the output voltage.
Vin_rms is the RMS value of the input voltage.
According to the faraday’s law of induction, the winding number of the inductance can be got:
L1 I peak
N L1 
Ae  Bm

L1 VCS _ REF
Ae  Bm  R5
Where,
Ae is the core effective area.
Bm is the maximum magnetic flux density.
The AL1678-20B/10B/08B has designed the minimum tON time and maximum tON time, the tON_MIN is about 700ns and the tON_MAX time is about
35µs. In buck topology we can get the equation Vin_rms-VO = L*Ipeak/tON. If the inductance is very small, it leads to the tON becoming smaller, when
the system’s tON is smaller than tON_MIN, the device can’t detect the peak current of the system leading to wrong output current. While if the
inductance is very large, it leads to the t ON becoming longer, when the system’s tON is longer than the tON_MAX, the system will trigger OVP, and
the LED will flicker. So the suitable value of the inductance is very important.
The AL1678-20B/10B/08B has also designed the minimum tOFF time and the maximum tOFF time, the tOFF_MIN time is about 6µs and tOFF_MAX time
is about 200µs. In buck topology we can get the equation V O = L*Ipeak/tOFF. If the inductance is very small, it leads to the t OFF becoming much
smaller, when the system’s tOFF is smaller than tOFF_MIN, the system will enter DCM mode, and the output current will be wrong. While if the
inductance is very large, it leads to the tOFF becoming much longer, when the system’s tOFF is longer than the tOFF_MAX, the system will enter CCM
mode, and the output current will also be wrong. So the suitable value of the inductance is very important.
Consider these parameters, two examples of the typical application inductance is recommended as below:
System Spec
Inductance Value
System Frequency
tON_MIN
tOFF
60V/150mA (85 to 277VAC)
2.3mH
60KHz (230VAC)
2.5µs (265VAC)
11.5µs
42V/100mA (85 to 277VAC)
2.5mH
62KHz (230VAC)
1.7µs (265VAC)
12.1µs
Fault Protection
Setting Output Open Voltage
The AL1678-20B/10B/08B has output open voltage protection, and the output voltage is controlled when the LED is open, which can prevent the
output voltage increasing to a very high value. This feature can help the system designer to select a smaller volume capacitor. The output voltage
is set by the external resistor R3 shown in Figure 1.
When the LED is open, the tOFF time can be calculated as
tOFF 
L1  VCS _ REF
VOVP  R 5
Where,
AL1678-20B/10B/08B
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AL1678-20B/10B/08B
Application Information (Cont.)
VOVP is the output open voltage.
When the LED is open, the output voltage is set by R3, and R3 is
NEW PRODUCT
R3 
VROVP _ REF  tOFF
40  CREF  VCS _ REF

VROVP _ REF  L1
40  CREF  VOVP  R5
Where,
VROVP_REF is the internal ROVP pin 0.46V’s reference.
CREF is the internal 6pF capacitor.
Output Short Protection
When the LED is shorted, the device can’t detect the demagnetization time, the device controls the system operation at 5K’s low frequency.
Thermal Fold Back Function
AL1678-20B/10B/08B has thermal fold back function, it adopts self-adaptive control method which can prevent the system breaking down caused
by high temperature. The overheating temperature is set at +140°C, when the temperature of the IC is higher than +140°C the device will
decrease the reference of the CS linearly till OTP happens. By this way, the device can control the system’s output power at high ambient
temperature, so the quantity of heat of the system can be controlled and temperature of the system is controlled, So the safety of the system at
high temperature is got enhanced.
Over Temperature Protection
The AL1678-20B/10B/08B has OTP protection function. When the temperature is increased to +170°C, the IC will trigger over temperature
protection which leads to a latch operating mode. When OTP happens, the system can restart under the condition that the system’s AC source
supply is powered off first.
Recommended Applications
The AL1678-20B/10B/08B integrates different MOSFET to adapt different wattage application. And the output current is limited by the internal
integrated MOSFET and the SO-7 package’s heat dissipation capability. And the minimum output voltage is limited by the LEB time, the minimum
output voltage is recommended to 15V. So the recommended application is given below:
Note 10:
Device
Output Power Coverage
Maximum Output Current (Note 10)
Minimum Output Voltage
AL1678-20B
≤15W
≤240mA
15V
AL1678-10B
≤10W
≤180mA
15V
AL1678-08B
(Note 11)
≤8W
≤120mA
15V
The higher output current is possible with extra power dissipation solution.
AL1678-20B/10B/08B
Document number: DS37637 Rev. 1 - 2
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AL1678-20B/10B/08B
Ordering Information
AL1678 - XX X XX - 13
NEW PRODUCT
Product Name
Current Option
MOSFET Voltage
Package
Packing
08 : 0.8A
10 : 1.0A
20 : 2.0A
B: 500V
S7 : SO-7
13 :13" Tape & Reel
13” Tape and Reel
Part Number
Package Code
Package
Quantity
Part Number Suffix
AL1678-20BS7-13
S7
SO-7
4000/Tape & Reel
-13
AL1678-10BS7-13
S7
SO-7
4000/Tape & Reel
-13
AL1678-08BS7-13
(Note 11)
S7
SO-7
4000/Tape & Reel
-13
Note 11:
The AL1678-08BS7-13 is still under development and not orderable.
Marking Information
(Top View)
7
6
5
Logo
Part Number
1678-20B for 2.0A/500V
1678-10B for 1.0A/500V
1678-08B for 0.8A/500V
1678 - ZZZ
YY WW X X
1
AL1678-20B/10B/08B
Document number: DS37637 Rev. 1 - 2
YY : Year : 15,16,17 ~
WW : Week : 01~52; 52
represents 52 and 53 week
X X : Internal Code
2
3
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AL1678-20B/10B/08B
Package Outline Dimensions (All dimensions in mm (inch).)
(1)
Package Type: SO-7
5.800(0.228)
1.350(0.053)
1.750(0.069)
NEW PRODUCT
6.200(0.244)
0.330(0.013)
0.510(0.020)
2.54(0.100)
TYP
4.700(0.185)
5.100(0.201)
1.270(0.050)
TYP
0.080(0.003)
0.250(0.010)
3.800(0.150)
4.000(0.157)
1.250(0.049)
1.500(0.059)
0.350(0.014)
TYP
0°
8°
Option 1
0.450(0.017)
0.800(0.031)
45°
0.150(0.006)
0.250(0.010)
Option 2
Note: Eject hole, oriented hole and mold mark is optional.
AL1678-20B/10B/08B
Document number: DS37637 Rev. 1 - 2
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AL1678-20B/10B/08B
Suggested Pad Layout
Package Type: SO-7
NEW PRODUCT
(1)
G
Z
E1
Y
X
E
Dimensions
Z
(mm)/(inch)
G
(mm)/(inch)
X
(mm)/(inch)
Y
(mm)/(inch)
E
(mm)/(inch)
E1
(mm)/(inch)
Value
6.900/0.272
3.900/0.154
0.650/0.026
1.500/0.059
1.270/0.050
2.540/0.100
AL1678-20B/10B/08B
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AL1678-20B/10B/08B
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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
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written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
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failure of the life support device or to affect its safety or effectiveness.
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use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related
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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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