AL1665
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AL1665
NEW PROD UCT
HIGH PERFORMANCE DIMMABLE LED CONTROLLER
Description
The AL1665 is a high performance single stage flyback and buck-
boost controller, targeting dimmable LED lighting application. It is a
Primary Side Regulation (PSR) controller which can provide accurate
Constant Current (CC) regulation without opto-coupler and secondary
control circuitry. It can be operated at BCM mode which results in low
EMI and high efficiency, and keeps high Power Factor (PF) and low
Total Harmonic Distortion (THD) under universal input voltage.
The AL1665 can support analog/PWM dimming modes. When a
50mV to 2.5V DC signal is applied on ADIM pin, the device will be
operated in analog dimming mode. The analog dimming range is 5%
to 100%. When a PWM signal is applied to NTC/PWM pin, the device
will be operated at PWM dimming mode. The PWM dimming range is
0.5% to 100% (1k PWM dimming frequency).
The AL1665 features low operation current. It integrates multiple
protections including over voltage, short circuit, over current and over
temperature.
The AL1665 is available in SO-8 (Standard) package.
Features
Primary Side Regulation without Opto-Coupler
Valley Switching for Low Switching Loss
Low Start-Up Current
Support Analog and PWM Dimming
Analog Dimming Range: 5% to 100%
PWM Dimming Range: 0.5% to 100% (1k PWM Frequency)
Internal Protections
Under Voltage Lock Out (UVLO)
Output Over Voltage Protection (OVP)
Output Short Protection (OSP)
Over Current Protection (OCP)
CS Short Protection
Winding Short Circuit Protection
Secondary Diode Short Protection
Shorted Current Sense Protection
User Programmable NTC Based Thermal Foldback
Internal Thermal Fold-Back Protection (TFP)
Over Temperature Protection (OTP)
Low System Cost
High PF>0.9 and Low THD<20%
High Efficiency
Tight LED Current Variation Range
LED Current Line Regulation: ±2%
LED Current Load Regulation: ±2% Full Load to Half Load
Tight Output Open Voltage Variation Range
Package: SO-8 (Standard)
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Pin Assignments
(Top View)
1
2
3
4
8
6
5
7
SO-8 (Standard)
Applications
General LED Lighting Driver with Dimming Function
General Purpose Constant Current Source
LED Backlighting Driver
Smart LED Lighting
Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant.
2. See https://www.diodes.com/quality/lead-free/ 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.
AL1665
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AL1665
NEW PROD UCT
Typical Applications Circuit
T1
OUT
+
VCC
OUT
CS
GND
U1
R5
R6
R4 D1
C6
RTH
AC
Input
F
1
VR
1
DB1
C2
L1
C1
RCS
R10
FB
COMP
D2
C5
R14
C7
D3
Q1
CCOMP
Aux
NTC/PWM
R9
D4
AL1665
ADIM
RCOMP
CVCC
R11
Flyback Application Circuit
T1 OUT
VCC
OUT
CS
GND
R5
R6
R4 D1
C6
RTH
AC
Input
F
1
VR
1
DB1
C2
L1
C1
RCS
FB
COMP
Q1
Aux
NTC/PWM
R9
D4
AL1665
D3
+
R11
ADIM
CCOMP
RCOMP
CVCC
Buck-Boost Application Circuit
Pin Descriptions
Pin Number
Pin Name
Function
1
ADIM
Analog Dimming Input Pin
2
NTC/PWM
NTC Input Pin for Thermal Foldback/PWM Dimming Input Pin
3
COMP
Loop Compensation Pin
4
CS
Current Sense Pin, Connect This Pin to the Source of the Primary Switch
5
GND
Ground
6
OUT
Gate Driver Output
7
VCC
Supply Voltage of Gate Driver and Control Circuits of the IC
8
FB
The Feedback Voltage Sensing from the Auxiliary Winding
AL1665
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AL1665
NEW PROD UCT
Functional Block Diagram
Valley
Detector Logical
Control
UVLO
&Bias
Driver
-
+
COMP
FB
OVP
CS
VCC
OUT
Gm
OTP
GND
Analog
Dim
Control
VREF
NTC/
PWM
ADIM
-
+
1.2V OCP
TFP
VREF
VREF
Internal
Temperature
Sense
1
2
3
4
5
8
7
6
Thermal
Foldback &
PWM Dim
OTP
Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) (Note 4)
Symbol
Parameter
Rating
Unit
VCC
Power Supply Voltage
-0.3 to 30
V
VCS
Voltage at CS to GND
-0.3 to 7
V
VFB
FB Input Voltage
-0.3 to 7
V
VCOMP
Voltage at Loop Compensation Pin
-0.3 to 7
V
VOUT
Driver Output Voltage
-0.3 to 20
V
VNTC/PWM
Voltage at NTC/PWM to GND
-0.3 to 7
V
VADIM
Voltage at ADIM to GND
-0.3 to 7
V
TJ
Operating Junction Temperature
-40 to +150
°C
TSTG
Storage Temperature
-65 to +150
°C
TLEAD
Lead Temperature (Soldering, 10s)
+300
°C
PD
Power Dissipation at TA = +50°C
0.65
W
θJA
Thermal Resistance (Junction to Ambient)
136
°C /W
θJC
Thermal Resistance (Junction to Case)
30
°C /W
–
ESD (Human Body Model)
2000
V
ESD (Charged-Device Model)
1000
V
Note: 4. Stresses greater than those listed under Absolute Maximum Ratings can 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 can affect device reliability. All voltages unless otherwise stated are measured with respect
to GND.
AL1665
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AL1665
NEW PROD UCT
Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.)
Symbol
Parameter
Min
Max
Unit
TA
Ambient Temperature (Note 5)
-40
+105
°C
VCC
Operating VCC Voltage (Note 6)
8.5
VCC_OVP (Min)
V
Notes: 5. The device may operate normally at +125°C ambient temperature under the condition not triggers temperature protection.
6. ICC should be limited less than 5mA.
Electrical Characteristics (@TA = +25°C, unless otherwise specified.)
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
UVLO Section
VCC_TH
Startup Threshold Voltage
–
15.8
18.5
19.5
V
VOPR_MIN
Minimal Operating Voltage
After Turn On
5.8
7.8
9
V
VCC_OVP
VCC OVP Voltage
–
21.8
25
29.5
V
Standby Current Section
IST
Startup Current
VCC = VCC_TH -0.5V,
Before Start Up
–
120
300
µA
ICC
Operating Current
FB, CS Connect to GND,
CGATE = 100pF
–
2
4
mA
ICC_OVP
Shunt Current in OVP Mode
VCC > VCC_OVP
3.1
–
–
mA
Drive Output Section
tR
Output Voltage Rise Time (Note 7)
CL = 1nF
–
100
–
ns
tF
Output Voltage Fall Time (Note 7)
CL = 1nF
–
100
–
ns
VOUT_CLAMP
Output Clamp Voltage
VCC = 20V
9.8
12
15.5
V
tON_MIN
Minimum On Time (Note 7)
–
–
1000
2010
ns
tON_MAX
Maximum On Time
–
–
20
31
µs
tOFF_MAX
Maximum Off Time
–
–
290
405
µs
fMAX
Maximum Frequency
–
–
150
–
kHz
Internal CS Reference
VREF
Internal Reference Voltage
–
0.394
0.4
0.406
V
VCS_CLAMP
Primary Current Clamp Voltage
–
1.8
2
2.5
V
VCS_OCP
Primary Over Current Voltage
–
–
3
–
V
Error Amplifier
Gm
Trans-Conductance
–
–
27
–
µA/V
ISOURCE
Amplifier Source Current
–
–
7.2
–
µA
Feedback Input Section
VFB_CV
FB CV Threshold
–
2.5
3.0
3.5
V
ADIM Section
–
Analog Dimming Range on ADIM
–
0.05
–
2.5
V
–
Analog Dimming High Level
–
2.45
2.5
2.55
V
–
Analog Dimming Range Ratio
–
5%
–
100%
–
Note: 7. These parameters, although guaranteed by design, are not 100% tested in production.
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AL1665
NEW PROD UCT
Electrical Characteristics (@TA = +25°C, unless otherwise specified.) (continued)
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
NTC/PWM Section
VNTC/PWM(PULL-UP)
Pull-Up Voltage when NTC/PWM Open
NTC/PWM Pin Open
–
2.5
–
V
IOTP(REF)
Reference Current for Direct Connection of
NTC/PWM (Note 9)
–
70.5
85
91
A
VOTP(OFF)
Fault Detection Level for OTP (Note 8)
VNTC/PWM Falling
–
0.50
–
V
VOTP(ON)
NTC/PWM Pin Level for Operation Recovery
after an OTP Detection
VNTC/PWM Rising
–
0.70
–
V
tOTP(START)
OTP Blanking Time when Circuit Starts
Operating (Note 9)
–
250
–
370
s
VTF(START)
NTC/PWM Pin Voltage at which Thermal
Fold−Back Starts (VREF is Decreased)
–
0.94
1.00
1.06
V
VTF(STOP)
NTC/PWM Pin Voltage at which Thermal
Fold−Back Stops (VREF is Clamped to VREF50)
–
0.64
0.69
0.74
V
VREF(50)
VREF @ VNTC/PWM = 600mV (Percent of VREF)
–
40
50
60
%
Thermal Fold-Back Section
TREG
Overheating Temperature Regulation (Note 7)
–
–
+150
–
°C
Over Temperature Protection Section
–
Shutdown Temperature (Notes 7, 8)
–
–
+180
–
°C
Notes: 7. These parameters, although guaranteed by design, are not 100% tested in production.
8. The device will latch when OTP happens and won’t be operated constantly at this temperature.
9. At startup, when VCC reaches VCC(ON), the controller blanks OTP for more than 250s to avoid detecting an OTP fault by allowing the NTC/PWM pin voltage to
reach its nominal value if a filtering capacitor is connected to the NTC/PWM pin.
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AL1665
NEW PROD UCT
Performance Characteristics (Note 10)
Startup Threshold Voltage vs. Ambient
Temperature
Minimum Operating Voltage vs. Ambient
Temperature
VCC OVP Voltage vs. Ambient Temperature
Startup Current vs. Ambient Temperature
Operating Current vs. Ambient Temperature
CS Reference Voltage vs. Ambient Temperature
Note: 10. These electrical characteristics are tested under DC condition. The ambient temperature is equal to the junction temperature of the device.
-40 -20 0 20 40 60 80 100 120
16.0
16.5
17.0
17.5
18.0
18.5
19.0
VCC_TH (V)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
6.0
6.2
6.4
6.6
6.8
7.0
7.2
7.4
7.6
7.8
8.0
VOPR_MIN (V)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
0.380
0.385
0.390
0.395
0.400
0.405
0.410
VCS_REF (V)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
ICC_OPR (mA)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
20
21
22
23
24
25
26
27
28
29
30
VCC_OVP (V)
Ambient Temperature (oC)
-40 -20 0 20 40 60 80 100 120
50
70
90
110
130
150
170
190
210
230
250
ICC_ST (mA)
Ambient Temperature (oC)
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AL1665
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-40 -20 0 20 40 60 80 100 120
1.80
1.85
1.90
1.95
2.00
2.05
2.10
2.15
2.20
VCS_CLAMP (V)
Ambient Temperature (oC)
Performance Characteristics (continued)
CS Clamp Reference Voltage vs. Ambient
Temperature
FB CV Threshold vs. Ambient Temperature
FB CV Threshold vs. VCC Voltage
CS Reference Voltage vs. VCC Voltage
PWM Dimming Curve
Analog Dimming Curve
-40 -20 0 20 40 60 80 100 120
2.6
2.7
2.8
2.9
3.0
3.1
3.2
3.3
VFB_CV (V)
Ambient Temperature (oC)
7 9 11 13 15 17 19 21 23
2.4
2.6
2.8
3.0
3.2
3.4
3.6
VFB_CV (V)
VCC Voltage (V)
7 9 11 13 15 17 19 21 23
0.380
0.385
0.390
0.395
0.400
0.405
0.410
VCS_REF (V)
VCC Voltage (V)
010 20 30 40 50 60 70 80 90 100
0
10
20
30
40
50
60
70
80
90
100
Dimming percentage (%)
PWM Duty (%)
PWM Frequency=1kHz
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6
0
10
20
30
40
50
60
70
80
90
100
Dimming Percentage (%)
VADIM (V)
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Application Information
The AL1665 is a constant current high PF flyback and buck-boost controller with Primary Side Regulation (PSR), targeting LED lighting
applications. The device eliminates the opto-couplers or the secondary feedback circuits, which is helpful to cost down the whole system. High
power factor is achieved by constant on-time operation. In order to reduce the switching losses and improve EMI performance, quasi-resonant
switching mode is applied. The AL1665 integrates multiple protections including UVLO protection, VCC over voltage protection, output open
voltage protection, over current protection, thermal fold-back protection and over temperature protection. The AL1665 can support analog and
PWM dimming modes.
T1
OUT
+
VCC
OUT
CS
GND
U1
R5
R6
R4 D1
C6
RTH
AC
Input
F
1
VR
1
DB1
C2
L1
C1
RCS
R10
FB
COMP
D2
C5
R14
C7
D3
Q1
CCOMP
Aux
NTC/
PWM
R9
D4
AL1665
ADIM
RCOMP
CVCC
R11
Figure 1. Flyback Application Circuit
T1 OUT
VCC
OUT
CS
GND
R5
R6
R4 D1
C6
RTH
AC
Input
F
1
VR
1
DB1
C2
L1
C1
RCS
FB
COMP
Q1
Aux
NTC/
PWM
R9
D4
AL1665
D3
+
R11
ADIM
CCOMP
RCOMP
CVCC
Figure 2. Buck-Boost Application Circuit
Start-Up
After AC supply is powered on, the capacitor CVCC across VCC and GND pin will be charged up by BUS voltage through a start-up resistor RTH.
Once VCC reaches VCC_TH, the internal blocks start to work. VCC will be supplied by VBUS until the auxiliary winding of flyback transformer could
supply enough energy to maintain VCC above VOPR_MIN. If VCC voltage is lower than VOPR_MIN, switch will be turned off.
After VCC exceeds VCC_TH, the drive blocks won’t start to switch on/off signals until VCOMP is higher than the initial voltage VCOMP_ST, which can be
programmed by RCOMP. The formula is shown as below. Such design can program startup on time to reduce the startup time or the output
overshoot current.
COMPSTCOMP RAVV
7004.1
_
Where VCOMP_ST is the pre-charged voltage of COMP pin. RCOMP is shown as Figure 1.
Generally, a big capacitance of CCOMP is necessary to achieve high power factor and stabilize the system loop (1μF to 2μF is recommended). The
pre-charged voltage in start-up procedure can be programmed by RCOMP.
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Application Information (continued)
Protections
1. Output Open Protection (OVP)
The output voltage is reflected by the voltage on transformer’s auxiliary winding. Both the FB pin and the VCC pin of IC have the over voltage
protection function. When there is a rapid line and load transient, the output voltage may exceed the regulated value. If VCC exceeds VCC_OVP, the
VCC over voltage protection will be triggered, the switch will be turned off and the VCC will be discharged. Once VCC is lower than VOPR_MIN, the IC
will shut down and be powered on again by BUS voltage through start up resistor. If VFB exceeds VFB_CV, the FB over voltage protection will be
triggered, switch will be turned off and VCC will be latched for 16s, then VCC will be discharged. Once VCC is below VOPR_MIN. the IC will shut down
and be powered on again by BUS voltage through start up resistor. Power dissipation is low when FB over voltage protection happens.
Thus, output over voltage depends on the minimum voltage between both OVP protections’ limitation. It can be gotten by below formula.
__
56
,6
SS
OVP CC OVP FB CV
AUX AUX
NN
RR
V Min V V
N N R



Where VOVP is the output over voltage setting; R5 and R6 shown in Figure 1 are divider resistors connected from the auxiliary winding.
NAUX is the turns of auxiliary wind; NS is turns of the secondary wind. VCC_OVP is the OVP Voltage of VCC.
2. Output Short Protection (OSP)
When the output is shorted, the output voltage would drop down to zero. The output voltage of the auxiliary winding, which is proportional to the
output winding, will drop down too. If the VFB drops below 0.4V, the output short protection will be triggered, switch will be turned off and VCC will
be latched for 16s, then VCC will be discharged. Once VCC is below the VOPR_MIN, the IC will be shut down and powered on again by the BUS
voltage through the startup resistor. Power dissipation is low when output short protection happens.
3. Over Current Protection (OCP)
The AL1665 has a built-in cycle by cycle over current protection of primary inductor current. When CS pin voltage reaches the voltage VCS_CLAMP,
the switch will be turned off until next switch period. The maximum peak current (IPEAK (MAX)) of the inductor can be calculated as below:


Where VCS_CLAMP means primary current clamp voltage that is 2V.
RCS is current sense resister which is shown as Figure 1.
4. CS Short Protection
When CS pin is shorted to GND, CS voltage is latched to zero. If CS is detected lower than 0.3V for 7 pulses, the CS short protection will be
triggered, switch will be turned off and VCC will be latched for 16s, then VCC will be discharged. Once VCC is below VOPR_MIN, the IC will be shut
down and powered on again by the BUS voltage through the startup resistor. High rush current appears when CS is shorted to GND, and it may
damage the components.
5. Secondary Diodes/Primary Windings/Secondary Windings Short Protection
The CS voltage will be high when secondary diodes/primary windings/secondary windings are shorted. If the CS voltage is higher than VCS_OCP,
the protection will be triggered, switch will be turned off and VCC will be latched for 16s, then VCC will be discharged. Once VCC is below VOPR_MIN,
the IC will be shut down and powered on again by the BUS voltage through the startup resistor. Power dissipation is low when output short
protection happens.
6. Thermal Fold-back Protection (TFP)
Connect a NTC between the NTC/PWM pin and ground to detect an over temperature condition. In response to a high temperature (detected if
VNTC/PWM drops below VTF(START)), the circuit gradually reduces the LED current down 50% of its nominal value when VNTC/PWM reaches VTF(STOP),
in accordance with the characteristic of Figure 3. If this thermal fold-back cannot prevent the temperature from rising (testified by VNTC/PWM droping
below VOTP), the circuit would be latched off or enter the auto−recovery mode, and cannot be re-operated until VNTC/PWM exceeds VOTP(ON) to
provide some temperature hysteresis (around +10°C typically). The OTP thresholds nearly correspond to the following resistances of the NTC:
Thermal fold-back starts when RNTC <=RTF(START)(11.7k typically); Thermal fold-back stops when RNTC <=RTF(STOP) (8.0k typically); OTP
triggers when RNTC <= ROTP(OFF) (5.9k typically); OTP is removed when RNTC >= ROTP(ON) (8.0k typically). At startup, when VCC reaches
VCC(ON), the OTP comparator is blanked for at least 250s in order to allow the NTC/PWM pin voltage to reach its nominal value if a filtering
capacitor is connected to the NTC/PWM pin. This would avoid flickering of the LED light during turn-on.
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Application Information (continued)
VNTC/PWM
IOUT
IOUT(NOM)
Shutdown
50%IOUT(NOM)
VOTP(OFF) VTF(STOP)
VOTP(ON)
VTF(START)
Temperature Decreases
Temperature Increases
Figure 3. Output Current Reduction versus NTC/PWM Pin Voltage
7. Over Temperature Protection (OTP)
The AL1665 has built-in Over Temperature Protection (OTP) function. When the temperature goes up to +165°C, the over temperature protection
will be triggered, which leads to a latch mode protection. When OTP happens, the system needs to be powered off and restart.
Output Constant Current Control
According to the definition of mean output current, the mean output current can be obtained as below:
dt
t
t
II
SW
ONS
SPMEANO
0
_2
11
Where IO_MEAN is the mean output current; ISP is the secondary peak current of transformer;
tONS is the discharge time of secondary side of transformer; tSW is the switch period.
According to the principle of AL1665 closed loop control, the voltage of RCS will be sampled when switch is turned off and the value will be held
until discharge time tONS is over. It can be described by following formula:




Where IP is the primary peak current of transformer; RCS is the current sense resister which is shown as Figure 1.
tONS is the discharge time of secondary side of transformer; tSW is the switch period. VREF is internal reference voltage that is equal to 0.4V.
The peak current at secondary side has the following relationship with primary side peak current, if the effect of the leakage inductor is neglected.
SP PS P
I N I
Where NPS is the turns’ ratio of flyback transformer (NPS=1 for buck-boost); IP is the primary peak current of the transformer.
According to these above formulas, the mean output current can be induced finally by the expression below:
_2
PS REF
O MEAN CS
NV
IR
Where IO_MEAN is the mean output current; RCS is the current sense resister which is shown as Figure 1 and Figure 2;
VREF is the internal reference voltage that is equal to 0.4V; NPS is the turns’ ratio of flyback transformer (NPS=1 for buck-boost);
Therefore, the constant output current control can be realized with appropriate parameter design.
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Application Information (continued)
PF and THD Compensation Circuit
In typical application, AL1665 can provide PF>0.9 and THD <40%. It can improve PF>0.95 and THD<20% by adding the compensation circuit as
below. The VBUS is connected to bus line which is after the rectifier bridge. The COMP pin voltage will increase an offset that is almost followed
with bus line voltage in the circuit. Due to the COMP voltage controls the switch-on time, the phase difference between input voltage and input
current will be reduced, which can optimize the PF and THD. In the circuit, the range of resister value R12 is from 800kΩ to 1.5MΩ, and the range
of resistor value R13 is from 500Ω to 5.1kΩ. The Range of capacitance C11 is 1F to 2F. The PF and THD circuit can be improved by fine-tuning
these components.
COMP
CCOMP
RCOMP
VBUS
C11
R12
R13
Figure 4. PF and THD Compensation Circuit
Line Regulation Compensation Function
The AL1665 can achieve good line regulation by adjusting FB pull-up resistor RFB1 and CS external horizontal resistor RCS1. The circuit is shown
as Figure 5. IFB3 is the current that flows from GND to the internal FB pull-down resistor. IFB3 will be detected during tONP time, and flows into CS to
compensate VREF.

  




VREF is the internal reference voltage that is equal to 0.4V; K is conversion coefficient of IFB3 that is equal to 4; VIN is the input Voltage;
NAP is the turns’ ratio of auxiliary winding and primary winding;
RFB2 is the external FB pull-down resistor; RFB3 is the internal FB pull-down resistor that is connected to the system during tONP time, and equals
to 207Ω;
RCS2 is the internal horizontal resistor that is 6kΩ.
As RFB1 and RFB2 are far larger than RFB3, the output current can be calculated approximately as following:


- 

-


)
K
RCS
RCS1 RCS2
Q1 RFB1
RFB2
RFB3
IFB3
CS
FB
AL1665
VREF tONP
Figure 5. Line Regulation Compensation Circuit
AL1665
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NEW PROD UCT
020 40 60 80 100
0
20
40
60
80
100
Output Current Percentage (%)
PWM Duty (%)
PWM Frequency=1kHz
Application Information (continued)
Dimming Mode
The AL1665 can support two dimming modes: analog dimming and PWM dimming.
1. Analog Dimming Mode
In analog dimming mode, the dimming signal is added to ADIM pin directly to realize dimming function. The setting circuit is shown as Figure 6.
When VAPWM is higher than 2.5V, the driver will output 100% of rated current; when the voltage VADIM is in the range from 50mV to 2.5V, the
output current will be changed linearly with the voltage VAPWM. The dimming curve is shown as Figure 7 and the dimming range is from 2% to
100%.
ADIM
AL1665
50mv~2.5V
Dimming Signal
CAPWM
050mV 2.5V
5%
100%
Figure 6. Analog Dimming Setting Circuit
Figure 7. Analog Dimming Curve
2. PWM Dimming Mode
In PWM dimming mode, dimming signal will be added to NTC/PWM pin .The setting circuit is shown as Figure 8. The output current is chopped by
the dimming signal directly. The logic high level of the dimming signal needs to be higher than 1V while the logic low level is lower than 0.5V. The
switch is turned off at logic low level. The dimming curve is shown as Figure 9. The dimming range can be 100% to 0.5% with 1kHz frequency of
PWM signal.
NTC
/PWM
AL1665
PWM Dimming Signal
Figure 8. PWM Dimming Setting Circuit
Figure 9. PWM Dimming Curve
AL1665
Document number: DS41772 Rev. 1 - 2
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AL1665
NEW PROD UCT
Application Information (continued)
Operation Parameters Design
1. Setting the Current Sense Resistor RCS
The current sense resistance can be calculated as following:
_
2PS REF
CS O MEAN
NV
RI
Where IO_MEAN is the mean output current; RCS is the current sense resister which is shown as Figure 1;
VREF is the internal reference voltage that is equal to 0.4V; NPS is the turns’ ratio of flyback transformer (NPS=1 for buck-boost).
2. Setting Transformer Selection (T1)
NPS is limited by the electrical stress of the switch MOSFET, can be calculated by below formula.
_( ) _
_
90% 2
MOS BR DS IN MAX S
PS O D F
V V V
NVV
Where VMOS_(BR)DS is the breakdown voltage of the switch MOSFET. VIN_MAX is the max rated input voltage. ∆VS is the overshoot voltage
clamped by RCD snobbier during OFF time. VO is the output voltage. VD_F is the forward voltage of secondary diode. NPS is the turns’ ratio of
flyback transformer (NPS=1 for buck-boost);
For boundary conduction mode and constant on time method, the peak current of primary inductance can be calculated as below.
_
_
0_
2
2 sin( )
sin( ) 2 sin( )
O MEAN
P
IN RMS
PS
IN RMS PS
I
IV
Nd
V N Vo




Where VIN_RMS is the rate input voltage; IP is the primary inductance current. NPS is the turns’ ratio of flyback transformer (NPS=1 for buck-boost);
IO_MEAN is the mean output current; VO is the output voltage.
The switching frequency is not constant for AL1665 due to boundary conduction mode. To set the minimum switching frequency fMIN at the crest of
the minimum AC input, primary inductance can be obtained by below formula.
_
_
2
( 2 )
IN RMS PS O
P
P IN RMS PS O MIN
V N V
LI V N V f
Where VIN_RMS is the rate input voltage; IP is the primary inductance current. NPS is the turns’ ratio of flyback transformer (NPS=1 for buck-boost);
VO is the output voltage; fMIN is the minimum switching frequency at the crest of the minimum AC input.
According to the Faraday’s Law, the winding number of the inductance can be calculated by:
PP
Pem
LI
NAB
P
SPS
N
NN
Where,
Ae is the core effective area.
Bm is the maximum magnetic flux density.
AL1665
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NEW PROD UCT
Ordering Information
AL1665 X - X
Packing
Package
13 : 13" Tape & Reel
S : SO-8 (Standard)
Product Name
Part Number
Package Code
Package
13” Tape and Reel
Quantity
Part Number Suffix
AL1665S-13
S
SO-8 (Standard)
4000/Tape & Reel
-13
Marking Information
AL1665
(Top View)
YY WW X X
Logo
WW : Week : 01~52; 52
YY : Year : 19, 20, 21~
X X : Internal Code
8 7 6 5
123 4
represents 52 and 53 week
Marking ID
AL1665
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Package Outline Dimensions (All dimensions in mm.)
Please see http://www.diodes.com/package-outlines.html for the latest version.
(1) Package Type: SO-8 (Standard)
SO-8 (Standard)
Dim
Min
Max
Typ
A
--
1.75
--
A1
0.10
0.25
--
A2
1.25
1.65
--
A3
0.50
0.70
--
b
0.30
0.51
--
c
0.15
0.25
--
D
4.80
5.00
--
E
5.80
6.20
6.00
E1
3.80
4.00
--
e
--
--
1.27
h
0.25
0.50
--
L
0.45
0.82
--
Ø
0°
8°
--
All Dimensions in mm
Suggested Pad Layout
Please see http://www.diodes.com/package-outlines.html for the latest version.
(1) Package Type: SO-8 (Standard)
Dimensions
Value (in mm)
C
1.27
X
0.802
X1
4.612
Y
1.505
Y1
6.50
1
b
e
EA2
A1
Ø
c
A3
h
45°
D
E1
L
Seating Plane
Gauge Plane
OPTION A
(TOP VIEW)
OPTION B
(TOP VIEW)
A
CX
Y
Y1
X1
AL1665
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